Index

Contents

1. Introduction

Definition Meaning Historical Prospective Objective, scope and limitations

2. Literature

What How

3. Research Design

Hypothesis

4. Research

How Input and Output

5. Data Analysis

6. Synthesis

Introduction General Observation & Specification

7. Conclusion

Finding Implementation

Page 1

Initial Development of Computer Graphics...........................................................................2

Image types..........................................................................................................................5

2D computer graphics................................................................................................................5

3D computer graphics................................................................................................................6

Computer animation...................................................................................................................7

Concepts and principles.......................................................................................................7

Rendering.....................................................................................................................................8

Volume rendering......................................................................................................................10

3D modelling..............................................................................................................................10

Subfields in computer graphics..........................................................................................12

Geometry...................................................................................................................................13

Animation...................................................................................................................................14

Rendering...................................................................................................................................14

Geometry processing.......................................................................................................................15

Cloth modelling.................................................................................................................................15

Deformable solids...............................................................................................................17

Mass-spring models..................................................................................................................18

Finite element simulation.........................................................................................................18

Energy minimization methods.................................................................................................19

Shape matching........................................................................................................................19

Rigid-body based deformation................................................................................................19

Force-based cloth.....................................................................................................................20

Position-based dynamics.........................................................................................................20

Collision detection for deformable objects..........................................................................21

Rigid body dynamics........................................................................................................................22

Rigid body linear momentum..............................................................................................23

Page 2

Rigid body angular momentum...........................................................................................24

Angular momentum and torque..........................................................................................24

Applications........................................................................................................................25

AutoCAD origin...................................................................................................................26

AutoCAD LT.......................................................................................................................27

AutoCAD Freestyle.............................................................................................................27

Student versions.................................................................................................................27

Vertical programs...............................................................................................................28

AutoCAD Architecture......................................................................................................................28

Autodesk Maya.................................................................................................................................29

Awards........................................................................................................................................30

Overview.............................................................................................................................30

Maya Embedded Language....................................................................................................31

System requirements..........................................................................................................32

Operating systems..............................................................................................................32

Autodesk Revit..................................................................................................................................32

Modelling............................................................................................................................33

Intended use.......................................................................................................................34

Family based content.........................................................................................................34

Rendering...........................................................................................................................34

Autodesk 3ds Max............................................................................................................................35

Modelling techniques..........................................................................................................39

Polygon modelling.....................................................................................................................39

NURBS or non-uniform rational B-spline...............................................................................39

Surface tool/Editable patch object..........................................................................................40

Predefined primitives..........................................................................................................40

Predefined Standard Primitives list.........................................................................................41

Predefined Extended Primitives list........................................................................................41

Rendering...........................................................................................................................42

Page 3

Page 4

Definition

The development of computer graphics has made computers easier to interact

with, and better for understanding and interpreting many types of data.

Developments in computer graphics have had a profound impact on many types of

media and have revolutionized animation, movies and the video game industry. The

term computer graphics has been used in a broad sense to describe "almost

everything on computers that is not text or sound". Typically, the term computer

graphics refers to several different things:

the representation and manipulation of image data by a computer

the various technologies used to create and manipulate images

the images so produced, and

the sub-field of computer science which studies methods for digitally synthesizing

and manipulating visual content, see study of computer graphics

Meaning

Today, computers and computer-generated images touch many aspects of daily life.

Computer imagery is found on television, in newspapers, for example in weather

reports, or for example in all kinds of medical investigation and surgical procedures.

A well-constructed graph can present complex statistics in a form that is easier to

understand and interpret. In the media "such graphs are used to illustrate papers,

reports, thesis", and other presentation material.

Many powerful tools have been developed to visualize data. Computer generated

imagery can be categorized into several different types: 2D, 3D, 4D, 7D, and

animated graphics. As technology has improved, 3D computer graphics have

become more common, but 2D computer graphics are still widely used. Computer

graphics has emerged as a sub-field of computer science which studies methods for

digitally synthesizing and manipulating visual content. Over the past decade, other

specialized fields have been developed like information visualization, and scientific

visualization more concerned with "the visualization of three

dimensional phenomena (architectural, meteorological, medical, biological, etc.),

Page 5

where the emphasis is on realistic renderings of volumes, surfaces, illumination

sources, and so forth, perhaps with a dynamic (time) component".

Historical Prospective

The advance in computer graphics was to come from Ivan Sutherland. In 1961

Sutherland created another computer drawing program called Sketchpad. Using a

light pen, Sketchpad allowed one to draw simple shapes on the computer screen,

save them and even recall them later. The light pen itself had a small photoelectric

cell in its tip. This cell emitted an electronic pulse whenever it was placed in front of a

computer screen and the screen's electron gun fired directly at it. By simply timing

the electronic pulse with the current location of the electron gun, it was easy to

pinpoint exactly where the pen was on the screen at any given moment. Once that

was determined, the computer could then draw a cursor at that location.

Sutherland seemed to find the perfect solution for many of the graphics problems he

faced. Even today, many standards of computer graphics interfaces got their start

with this early Sketchpad program. One example of this is in drawing constraints. If

one wants to draw a square for example, s/he doesn't have to worry about drawing

four lines perfectly to form the edges of the box. One can simply specify that s/he

wants to draw a box, and then specify the location and size of the box. The software

will then construct a perfect box, with the right dimensions and at the right location.

Another example is that Sutherland's software modeled objects - not just a picture of

objects. In other words, with a model of a car, one could change the size of the tires

without affecting the rest of the car. It could stretch the body of the car without

deforming the tires.

These early computer graphics were Vector graphics, composed of thin lines

whereas modern day graphics are Raster based using pixels. The difference

between vector graphics and raster graphics can be illustrated with a shipwrecked

sailor. He creates an SOS sign in the sand by arranging rocks in the shape of the

letters "SOS." He also has some brightly colored rope, with which he makes a

second "SOS" sign by arranging the rope in the shapes of the letters. The rock SOS

sign is similar to raster graphics. Every pixel has to be individually accounted for.

The rope SOS sign is equivalent to vector graphics. The computers simply sets the

Page 6

starting point and ending point for the line and perhaps bend it a little between the

two end points. The disadvantages to vector files are that they cannot represent

continuous tone images and they are limited in the number of colors available.

Raster formats on the other hand work well for continuous tone images and can

reproduce as many colors as needed.

Also in 1961 another student at MIT, Steve Russell, created the first video game,

Spacewar. Written for the DEC PDP-1, Spacewar was an instant success and copies

started flowing to other PDP-1 owners and eventually even DEC got a copy. The

engineers at DEC used it as a diagnostic program on every new PDP-1 before

shipping it. The sales force picked up on this quickly enough and when installing new

units, would run the world's first video game for their new customers.

E. E. Zajac, a scientist at Bell Telephone Laboratory (BTL), created a film called

"Simulation of a two-giro gravity attitude control system" in 1963. In this computer

generated film, Zajac showed how the attitude of a satellite could be altered as it

orbits the Earth. He created the animation on an IBM 7090 mainframe computer.

Also at BTL, Ken Knowlton, Frank Sindon and Michael Noll started working in the

computer graphics field. Sindon created a film called Force, Mass and Motion

illustrating Newton's laws of motion in operation. Around the same time, other

scientists were creating computer graphics to illustrate their research. At Lawrence

Radiation Laboratory, Nelson Max created the films, "Flow of a Viscous Fluid" and

"Propagation of Shock Waves in a Solid Form." Boeing Aircraft created a film called

"Vibration of an Aircraft."

It wasn't long before major corporations started taking an interest in computer

graphics. TRW, Lockheed-Georgia, General Electric and Sperry Rand are among

the many companies that were getting started in computer graphics by the mid

1960's. IBM was quick to respond to this interest by releasing the IBM 2250 graphics

terminal, the first commercially available graphics computer.

Ralph Baer, a supervising engineer at Sanders Associates, came up with a home

video game in 1966 that was later licensed to Magnavox and called the Odyssey.

While very simplistic, and requiring fairly inexpensive electronic parts, it allowed the

player to move points of light around on a screen. It was the first consumer computer

graphics product.

Page 7

Also in 1966, Sutherland at MIT invented the first computer controlled head-mounted

display (HMD). Called the Sword of Damocles because of the hardware required for

support, it displayed two separate wireframe images, one for each eye. This allowed

the viewer to see the computer scene in stereoscopic 3D. After receiving his Ph.D.

from MIT, Sutherland became Director of Information Processing at ARPA

(Advanced Research Projects Agency), and later became a professor at Harvard.

Dave Evans was director of engineering at Bendix Corporation's computer division

from 1953 to 1962, after which he worked for the next five years as a visiting

professor at Berkeley. There he continued his interest in computers and how they

interfaced with people. In 1968 the University of Utah recruited Evans to form a

computer science program, and computer graphics quickly became his primary

interest. This new department would become the world's primary research center for

computer graphics.

In 1967 Sutherland was recruited by Evans to join the computer science program at

the University of Utah. There he perfected his HMD. Twenty years later, NASA would

re-discover his techniques in their virtual reality research. At Utah, Sutherland and

Evans were highly sought after consultants by large companies but they were

frustrated at the lack of graphics hardware available at the time so they started

formulating a plan to start their own company.

A student by the name of Edwin Catmull started at the University of Utah in 1970 and

signed up for Sutherland's computer graphics class. Catmull had just come from The

Boeing Company and had been working on his degree in physics. Growing up on

Disney, Catmull loved animation yet quickly discovered that he didn't have the talent

for drawing. Now Catmull (along with many others) saw computers as the natural

progression of animation and they wanted to be part of the revolution. The first

animation that Catmull saw was his own. He created an animation of his hand

opening and closing. It became one of his goals to produce a feature length motion

picture using computer graphics. In the same class, Fred Parke created an

animation of his wife's face. Because of Evan's and Sutherland's presence, UU was

gaining quite a reputation as the place to be for computer graphics research so

Catmull went there to learn 3D animation.

As the UU computer graphics laboratory was attracting people from all over, John

Warnock was one of those early pioneers; he would later found Adobe Systems and

Page 8

create a revolution in the publishing world with his PostScript page description

language. Tom Stockham led the image processing group at UU which worked

closely with the computer graphics lab. Jim Clark was also there; he would later

found Silicon Graphics, Inc.

The first major advance in 3D computer graphics was created at UU by these early

pioneers, the hidden-surface algorithm. In order to draw a representation of a 3D

object on the screen, the computer must determine which surfaces are "behind" the

object from the viewer's perspective, and thus should be "hidden" when the

computer creates (or renders) the image.

Literature

2D computer graphics

2D computer graphics are the computer-based generation of digital images—mostly

from two-dimensional models, such as 2D geometric models, text, and digital

images, and by techniques specific to them.

2D computer graphics are mainly used in applications that were originally developed

upon traditional printing and drawing technologies, such as typography,

cartography, technical drawing, advertising, etc.. In those applications, the two-

dimensional image is not just a representation of a real-world object, but an

independent artifact with added semantic value; two-dimensional models are

therefore preferred, because they give more direct control of the image than 3D

computer graphics, whose approach is more akin to photography than to typography.

Pixel artPixel art is a form of digital art, created through the use of raster graphics software,

where images are edited on the pixel level. Graphics in most old (or relatively limited)

computer and video games, graphing calculator games, and many mobile

phone games are mostly pixel art.

Page 9

Vector graphics

Vector graphics formats are complementary to raster graphics, which is the

representation of images as an array of pixels, as it is typically used for the

representation of photographic images [4] Vector graphics consists in encoding

information about shapes and colors that comprise the image, which can allow for

more flexibility in rendering. There are instances when working with vector tools and

formats is best practice, and instances when working with raster tools and formats is

best practice. There are times when both formats come together. An understanding

of the advantages and limitations of each technology and the relationship between

them is most likely to result in efficient and effective use of tools.

3D computer graphics3D computer graphics in contrast to 2D computer graphics are graphics that use

a three-dimensional representation of geometric data that is stored in the computer

for the purposes of performing calculations and rendering 2D images. Such images

may be for later display or for real-time viewing.

Despite these differences, 3D computer graphics rely on many of the

same algorithms as 2D computer vector graphics in the wire frame modeland 2D

computer raster graphics in the final rendered display. In computer graphics

software, the distinction between 2D and 3D is occasionally blurred; 2D applications

may use 3D techniques to achieve effects such as lighting, and primarily 3D may use

2D rendering techniques.

3D computer graphics are often referred to as 3D models. Apart from the rendered

graphic, the model is contained within the graphical data file. However, there are

differences. A 3D model is the mathematical representation of any three-

dimensional object. A model is not technically a graphic until it is visually displayed.

Due to 3D printing, 3D models are not confined to virtual space. A model can be

displayed visually as a two-dimensional image through a process called 3D

rendering, or used in non-graphical computer simulations and calculations. There are

some 3D computer graphics software for users to create 3D images.

Page 10

Computer animation

Computer animation is the art of creating moving images via the use of computers. It

is a subfield of computer graphics and animation. Increasingly it is created by means

of 3D computer graphics, though 2D computer graphics are still widely used for

stylistic, low bandwidth, and faster real-time rendering needs. Sometimes the target

of the animation is the computer itself, but sometimes the target is another medium,

such as film. It is also referred to as CGI (Computer-generated imagery or computer-

generated imaging), especially when used in films.

Virtual entities may contain and be controlled by assorted attributes, such as

transform values (location, orientation, and scale) stored in an

object's transformation matrix. Animation is the change of an attribute over time.

Multiple methods of achieving animation exist; the rudimentary form is based on the

creation and editing of key frames, each storing a value at a given time, per attribute

to be animated. The 2D/3D graphics software will interpolate between key frames,

creating an editable curve of a value mapped over time, resulting in animation. Other

methods of animation include procedural and expression-based techniques: the

former consolidates related elements of animated entities into sets of attributes,

useful for creating particle effects and crowd simulations; the latter allows an

evaluated result returned from a user-defined logical expression, coupled with

mathematics, to automate animation in a predictable way (convenient for controlling

bone behaviour beyond what a hierarchy offers in skeletal system set up).

To create the illusion of movement, an image is displayed on the

computer screen then quickly replaced by a new image that is similar to the previous

image, but shifted slightly. This technique is identical to the illusion of movement

in television and motion pictures.

ResearchImages are typically produced by  optical  devices; such as  cameras, 

mirrors, lenses, telescopes, microscopes, etc. and natural objects and phenomena,

such as the human eye or water surfaces.

Page 11

A digital image is a representation of a two-dimensional image in binary format as a

sequence of ones and zeros. Digital images include both vector images

and raster images, but raster images are more commonly used. In digital imaging,

a pixel (or picture element) is a single point in a raster image. Pixels are normally

arranged in a regular 2-dimensional grid, and are often represented using dots or

squares. Each pixel is a sample of an original image, where more samples typically

provide a more accurate representation of the original. The intensity of each pixel is

variable; in color systems, each pixel has typically three components such as red,

green, and blue.

GraphicsGraphics are visual presentations on some surface, such as a wall, canvas,

computer screen, paper, or stone to brand, inform, illustrate, or entertain. Examples

are photographs, drawings, line

art, graphs, diagrams, typography, numbers, symbols, geometric designs, map

s,engineering drawings, or other images. Graphics often combine text, illustration,

and color. Graphic design may consist of the deliberate selection, creation, or

arrangement of typography alone, as in a brochure, flier, poster, web site, or book

without any other element. Clarity or effective communication may be the objective,

association with other cultural elements may be sought, or merely, the creation of a

distinctive style.

RenderingRendering is the process of generating an image from a model (or models in what

collectively could be called a scene file), by means of computer programs. A scene

file contains objects in a strictly defined language or data structure; it would contain

geometry, viewpoint, texture,lighting, and shading information as a description of the

virtual scene. The data contained in the scene file is then passed to a rendering

program to be processed and output to a digital image or raster graphics image file.

The rendering program is usually built into the computer graphics software, though

others are available as plug-ins or entirely separate programs. The term "rendering"

may be by analogy with an "artist's rendering" of a scene. Though the technical

details of rendering methods vary, the general challenges to overcome in producing

Page 12

a 2D image from a 3D representation stored in a scene file are outlined as

the graphics pipeline along a rendering device, such as a GPU. A GPU is a purpose-

built device able to assist a CPU in performing complex rendering calculations. If a

scene is to look relatively realistic and predictable under virtual lighting, the rendering

software should solve the rendering equation. The rendering equation doesn't

account for all lighting phenomena, but is a general lighting model for computer-

generated imagery. 'Rendering' is also used to describe the process of calculating

effects in a video editing file to produce final video output.

3D projection

3D projection is a method of mapping three dimensional points to a two dimensional

plane. As most current methods for displaying graphical data are based on planar

two dimensional media, the use of this type of projection is widespread, especially in

computer graphics, engineering and drafting.

Ray tracing

Ray tracing is a technique for generating an image by tracing the path

of light through pixels in an image plane. The technique is capable of producing a

very high degree ofphotorealism; usually higher than that of typical scanline

rendering methods, but at a greater computational cost.

Shading

Shading refers to depicting depth in 3D models or illustrations by varying levels

of darkness. It is a process used in drawing for depicting levels of darkness on paper

by applying media more densely or with a darker shade for darker areas, and less

densely or with a lighter shade for lighter areas. There are various techniques of

shading including cross hatching where perpendicular lines of varying closeness are

drawn in a grid pattern to shade an area. The closer the lines are together, the

darker the area appears. Likewise, the farther apart the lines are, the lighter the area

appears. The term has been recently generalized to mean that shaders are applied.

Page 13

Texture mapping

Texture mapping is a method for adding detail, surface texture, or colour to

a computer-generated graphic or 3D model. Its application to 3D graphics was

pioneered by Dr Edwin Catmull in 1974. A texture map is applied (mapped) to the

surface of a shape, or polygon. This process is akin to applying patterned paper to a

plain white box. Multitexturing is the use of more than one texture at a time on a

polygon.[6] Procedural textures (created from adjusting parameters of an underlying

algorithm that produces an output texture), and bitmap textures (created in an image

editing application) are, generally speaking, common methods of implementing

texture definition from a 3D animation program, while intended placement of textures

onto a model's surface often requires a technique known as UV mapping.

Anti-aliasing

Rendering resolution-independent entities (such as 3D models) for viewing on a

raster (pixel-based) device such as a LCD display or CRT television inevitably

causes aliasing artifactsmostly along geometric edges and the boundaries of texture

details; these artifacts are informally called "jaggies". Anti-aliasing methods rectify

such problems, resulting in imagery more pleasing to the viewer, but can be

somewhat computationally expensive. Various anti-aliasing algorithms (such

as supersampling) are able to be employed, then customized for the most efficient

rendering performance versus quality of the resultant imagery; a graphics artist

should consider this trade-off if anti-aliasing methods are to be used. A pre-anti-

aliased bitmap texture being displayed on a screen (or screen location) at a

resolution different than the resolution of the texture itself (such as a textured model

in the distance from the virtual camera) will exhibit aliasing artifacts, while

any procedurally-defined texture will always show aliasing artifacts as they are

resolution-independent; techniques such asmipmapping and texture filtering help to

solve texture-related aliasing problems.

Page 14

Volume renderingVolume rendering is a technique used to display a 2D projection of a 3D

discretely sampled data set. A typical 3D data set is a group of 2D slice images

acquired by a CT or MRI scanner.

Usually these are acquired in a regular pattern (e.g., one slice every millimetre) and

usually have a regular number of image pixels in a regular pattern. This is an

example of a regular volumetric grid, with each volume element,

or voxel represented by a single value that is obtained by sampling the immediate

area surrounding the voxel.

3D modelling3D modelling is the process of developing a mathematical, wireframe representation

of any three-dimensional object, called a "3D model", via specialized software.

Models may be created automatically or manually; the manual modelling process of

preparing geometric data for 3D computer graphics is similar to plastic arts such

as sculpting. 3D models may be created using multiple approaches: use

of NURBS curves to generate accurate and smooth surface patches, polygonal

mesh modelling (manipulation of faceted geometry), or polygonal

mesh subdivision(advanced tessellation of polygons, resulting in smooth surfaces

similar to NURBS models). A 3D model can be displayed as a two-dimensional

image through a process called 3D rendering.

Pioneers in graphic design

Charles Csuri

Charles Csuri is a pioneer in computer animation and digital fine art and created the

first computer art in 1964. Csuri was recognized by Smithsonian as the father of

digital art and computer animation, and as a pioneer of computer animation by

the Museum of Modern Art (MoMA) and Association for Computing Machinery-

SIGGRAPH.

Donald P. Greenberg

Page 15

Donald P. Greenberg is a leading innovator in computer graphics. Greenberg has

authored hundreds of articles and served as a teacher and mentor to many

prominent computer graphic artists, animators, and researchers such as Robert L.

Cook, Marc Levoy, and Wayne Lytle. Many of his former students have won

Academy Awards for technical achievements and several have won

the SIGGRAPH Achievement Award. Greenberg was the founding director of the

NSF Center for Computer Graphics and Scientific Visualization.

A. Michael Noll

Noll was one of the first researchers to use a digital computer to create artistic

patterns and to formalize the use of random processes in the creation of  visual arts.

He began creating digital computer art in 1962, making him one of the earliest digital

computer artists. In 1965, Noll along with Frieder Nake and Georg Nees were the

first to publicly exhibit their computer art. During April 1965, the Howard Wise Gallery

exhibited Noll's computer art along with random-dot patterns by Bela Julesz.

Other pioneers

Jim Blinn

Arambilet

Benoît B. Mandelbrot

Henri Gouraud

Bui Tuong Phong

Pierre Bézier

Paul de Casteljau

Daniel J. Sandin

Alvy Ray Smith

Ton Roosendaal

Ivan Sutherland

Page 16

Computer graphics studies the manipulation of visual and geometric information

using computational techniques. It focuses on

the mathematical and computational foundations of image generation and

processing rather than purely aesthetic issues. Computer graphics is often

differentiated from the field of visualization, although the two fields have many

similarities.

Connected studies include:

Scientific visualization

Information visualization

Computer vision

Image processing

Computational Geometry

Computational Topology

Applied mathematics

Applications of computer graphics include:

Special effects

Visual effects

Video games

Digital art

Subfields in computer graphics

A broad classification of major subfields in computer graphics might be:

1. Geometry: studies ways to represent and process surfaces

2. Animation: studies with ways to represent and manipulate motion

3. Rendering: studies algorithms to reproduce light transport

4. Imaging: studies image acquisition or image editing

Page 17

Geometry

The subfield of geometry studies the representation of three-dimensional objects in a

discrete digital setting. Because the appearance of an object depends largely on its

exterior, boundary representations are most commonly used. Two

dimensional surfaces are a good representation for most objects, though they may

be non-manifold. Since surfaces are not finite, discrete digital approximations are

used. Polygonal meshes (and to a lesser extent subdivision surfaces) are by far the

most common representation, although point-based representations have become

more popular recently (see for instance the Symposium on Point-Based Graphics).

These representations are Lagrangian, meaning the spatial locations of the samples

are independent. Recently, Eulerian surface descriptions (i.e., where spatial samples

are fixed) such as level sets have been developed into a useful representation for

deforming surfaces which undergo many topological changes (with fluids being the

most notable example).

Geometry Subfields

Implicit surface modeling - an older subfield which examines the use of algebraic

surfaces, constructive solid geometry, etc., for surface representation.

Digital geometry processing - surface reconstruction, simplification, fairing, mesh

repair, parameterization, remeshing, mesh generation, surface compression, and

surface editing all fall under this heading.

Discrete differential geometry - a nascent field which defines geometric quantities for

the discrete surfaces used in computer graphics.

Point-based graphics - a recent field which focuses on points as the fundamental

representation of surfaces.

Subdivision surfaces

Page 18

Out-of-core mesh processing - another recent field which focuses on mesh datasets

that do not fit in main memory.

AnimationThe subfield of animation studies descriptions for surfaces (and other phenomena)

that move or deform over time. Historically, most work in this field has focused on

parametric and data-driven models, but recently physical simulation has become

more popular as computers have become more powerful computationally.

Subfields

Performance capture

Character animation

Physical simulation (e.g. cloth modelling, animation of fluid dynamics, etc.)

Rendering

Rendering generates images from a model. Rendering may simulate light

transport to create realistic images or it may create images that have a particular

artistic style in non-photorealistic rendering. The two basic operations in realistic

rendering are transport (how much light passes from one place to another) and

scattering (how surfaces interact with light). See Rendering (computer graphics) for

more information.

Transport

Page 19

Transport describes how illumination in a scene gets from one place to

another. Visibility is a major component of light transport.

Scattering

Models of scattering and shading are used to describe the appearance of a surface.

In graphics these problems are often studied within the context of rendering since

they can substantially affect the design of rendering algorithms. Shading can be

broken down into two orthogonal issues, which are often studied independently:

1. scattering - how light interacts with the surface at a given point

2. shading - how material properties vary across the surface

The former problem refers to scattering, i.e., the relationship between incoming and

outgoing illumination at a given point. Descriptions of scattering are usually given in

terms of a bidirectional scattering distribution function or BSDF. The latter issue

addresses how different types of scattering are distributed across the surface (i.e.,

which scattering function applies where). Descriptions of this kind are typically

expressed with a program called a shader. (Note that there is some confusion since

the word "shader" is sometimes used for programs that describe

local geometric variation.)

Other subfields

Physically-based rendering - concerned with generating images according to the

laws of geometric optics.

Real time rendering - focuses on rendering for interactive applications, typically using

specialized hardware like GPUs.

Non-photorealistic rendering.

Relighting - recent area concerned with quickly re-rendering scenes.

Geometry processing

Page 20

Geometry processing, or mesh processing, is a fast-growing area of research that

uses concepts from applied mathematics, computer science and engineering to

design efficient algorithms for the acquisition, reconstruction, analysis, manipulation,

simulation and transmission of complex 3D models. Applications of geometry

processing algorithms already cover a wide range of areas

from multimedia, entertainment and classical computer-aided design, to biomedical

computing, reverse engineering and scientific computing.

Cloth modelling

Cloth modelling is the term used for simulating cloth within a computer program

usually in the realm of computer graphics . The main approaches used for this may

be classified into three basic types: geometric, physical, and particle/energy.

Most models of cloth are based on "particles" of mass connected together in some

manner of mesh. Newtonian Physics is used to model each particle through the use

of a "black box" called a physics engine. This involves using the basic law of motion

(Newton's Second Law):

In all of these models, the goal is to find the position and shape of a piece of fabric

using this basic equation and several other methods.

Geometric methods

Weil pioneered the first of these, the geometric technique, in 1986. [1] His work was

focused on approximating the look of cloth by treating cloth like a collection of cables

and using Hyperbolic cosine (catenary) curves. Because of this, it is not suitable for

dynamic models but works very well for stationary or single-frame renders [1]. This

technique creates an underlying shape out of single points; then, it parses through

each set of three of these points and maps a catenary curve to the set. It then takes

the lowest out of each overlapping set and uses it for the render.

Page 21

Physical methods

The second technique treats cloth like a grid work of particles connected to each

other by springs. Whereas the geometric approach accounted for none of the

inherent stretch of a woven material, this physical model accounts for stretch

(tension), stiffness, and weight:

E(Particlei,j) = ksEs,i,j + kbEb,i,j + kgEg,i,j

s terms are elasticity (by Hooke's Law)

b terms are bending

g terms are gravity (see Acceleration due to gravity)

Now we apply the basic principle of mechanical equilibrium in which all bodies seek

lowest energy by differentiating this equation to find the minimum energy.

Particle/energy methods

The last method is more complex than the first two. The particle technique takes the

physical technique from (f) a step further and supposes that we have a network of

particles interacting directly. That is to say, that rather than springs, we use the

energy interactions of the particles to determine the cloth’s shape. For this we use an

energy equation that adds on to the following:

UTotal = URepel + UStretch + UBend + UTrellis + UGravity

The energy of repelling is an artificial element we add to prevent

cloth from intersecting itself.

The energy of stretching is governed by Hooke's law as with the

Physical Method.

The energy of bending describes the stiffness of the fabric

The energy of trellising describes the shearing of the fabric

(distortion within the plane of the fabric)

The energy of gravity is based on acceleration due to gravity

Page 22

We can also add terms for energy added by any source to this equation, then derive

and find minima, which generalizes our model. This allows us to model cloth

behaviour under any circumstance, and since we are treating the cloth as a

collection of particles its behaviour can be described with the dynamics provided in

our physics engine.

Dynamics

Soft body dynamics

Soft body dynamics is a field of computer graphics that focuses on visually realistic

physical simulations of the motion and properties of deformable objects (or soft

bodies). The applications are mostly in video games and film. Unlike in simulation

of rigid bodies, the shape of soft bodies can change, meaning that the relative

distance of two points on the object is not fixed. While the relative distances of points

are not fixed, the body is expected to retain its shape to some degree (unlike a fluid).

The scope of soft body dynamics is quite broad, including simulation of soft organic

materials such as muscle, fat, hair and vegetation, as well as other deformable

materials such as clothing and fabric. Generally, these methods only provide visually

plausible emulations rather than accurate scientific/engineering simulations, though

there is some crossover with scientific methods, particularly in the case of finite

element simulations. Several physics engines currently provide software for soft-

body simulation.

Deformable solids

The simulation of volumetric solid soft bodies can be realised by using a variety of

approaches.

Mass-spring models

In this approach, the body is modeled as a set of point masses (nodes) connected by

ideal weightless elastic springs obeying some variant ofHooke's law. The nodes may

Page 23

either derive from the edges of a two-dimensional polygonal mesh representation of

the surface of the object, or from a three-dimensional network of nodes and edges

modeling the internal structure of the object (or even a one-dimensional system of

links, if for example a rope or hair strand is being simulated). Additional springs

between nodes can be added, or the force law of the springs modified, to achieve

desired effects. Applying Newton's second law to the point masses including the

forces applied by the springs and any external forces (due to contact, gravity, air

resistance, wind, and so on) gives a system of differential equations for the motion of

the nodes, which is solved by standard numerical schemes for solving ODEs.

Rendering of a three-dimensional mass-spring lattice is often done using free form

deformation, in which the rendered mesh is embedded in the lattice and distorted to

conform to the shape of the lattice as it evolves.

Finite element simulation

This is a more physically accurate approach, which uses the widely used finite

element method to solve the partial differential equations which govern the dynamics

of an elastic material. The body is modeled as a three-dimensional elastic

continuum by breaking it into a large number of solid elements which fit together, and

solving for the stresses and strains in each element using a model of the material.

The elements are typically tetrahedral, the nodes being the vertices of the tetrahedra

(relatively simple methods exist[10][11] to tetrahedralize a three dimensional region

bounded by a polygon mesh into tetrahedra, similarly to how a two-

dimensional polygon may be triangulated into triangles). The strain (which measures

the local deformation of the points of the material from their rest state) is quantified

by the strain tensor  . The stress (which measures the local forces per-unit area in

all directions acting on the material) is quantified by the stress tensor  . Given the

current local strain, the local stress can be computed via the generalized form

of Hooke's law:   where   is the "elasticity tensor" which encodes the

material properties (parametrized in linear elasticity for an isotropic material by

the Poisson ratio and Young's modulus).

The equation of motion of the element nodes is obtained by integrating the stress

field over each element and relating this, via Newton's second law, to the node

accelerations.

Page 24

Pixelux (developers of the Digital Molecular Matter system) use a finite-element-

based approach for their soft bodies, using a tetrahedral mesh and converting the

stress tensor directly into node forces. Rendering is done via a form of free form

deformation.

Energy minimization methods

This approach is motivated by variational principles and the physics of surfaces,

which dictate that a constrained surface will assume the shape which minimizes the

total energy of deformation (analogous to a soap bubble). Expressing the energy of a

surface in terms of its local deformation (the energy is due to a combination of

stretching and bending), the local force on the surface is given by differentiating the

energy with respect to position, yielding an equation of motion which can be solved

in the standard ways.

Shape matching

In this scheme, penalty forces or constraints are applied to the model to drive it

towards its original shape (i.e. the material behaves as if it has shape memory). To

conserve momentum the rotation of the body must be estimated properly, for

example via polar decomposition. To approximate finite element simulation, shape

matching can be applied to three dimensional lattices and multiple shape matching

constraints blended.

Rigid-body based deformation

Deformation can also be handled by a traditional rigid-body physics engine,

modelling the soft-body motion using a network of multiple rigid bodies connected by

constraints, and using (for example) matrix-palette skinning to generate a surface

mesh for rendering. This is the approach used for deformable objects in Havoc.

Cloth simulation

In the context of computer graphics, cloth simulation refers to the simulation of soft

bodies in the form of two dimensional continuum elastic membranes, that is, for this

Page 25

purpose, the actual structure of real cloth on the yarn level can be ignored (though

modelling cloth on the yarn level has been tried). Via rendering effects, this is

capable of producing a visually plausible emulation of textiles and clothing, used in a

variety of contexts in video games, animation, and film. It can also be used to

simulate two dimensional sheets of materials other than textiles, such as deformable

metal panels or vegetation. In video games it is often used to enhance the realism of

clothed characters, which otherwise would be entirely animated.

Cloth simulators are generally based on mass-spring models, but a distinction must

be made between force-based and position-based solvers.

Force-based cloth

The mass-spring model (obtained from a polygonal mesh representation of the cloth)

determines the internal spring forces acting on the nodes at each time step (in

combination with gravity and applied forces). Newton's second law gives equations

of motion which can be solved via standard ODE solvers. To create high resolution

cloth with a realistic stiffness is not possible however with simple explicit solvers

(such as forward Euler integration), unless the time step is made too small for

interactive applications (since as is well known, explicit integrators are numerically

unstable for sufficiently stiff systems). Therefore implicit solvers must be used,

requiring solution of a large sparse matrix system (via e.g. the conjugate gradient

method), which itself may also be difficult to achieve at interactive frame rates. An

alternative is to use an explicit method with low stiffness, with ad hoc methods to

avoid instability and excessive stretching (e.g. strain limiting corrections).

Position-based dynamics

To avoid needing to do an expensive implicit solution of a system of ODEs, many

real-time cloth simulators (notably PhysX, Havok Cloth, and Maya nCloth)

use position based dynamics(PBD), an approach based on constraint relaxation. The

mass-spring model is converted into a system of constraints, which demands that

the distance between the connected nodes be equal to the initial distance. This

system is solved sequentially and iteratively, by directly moving nodes to satisfy each

constraint, until sufficiently stiff cloth is obtained. This is similar to a Gauss-

Page 26

Seidel solution of the implicit matrix system for the mass-spring model. Care must be

taken though to solve the constraints in the same sequence each timestep, to avoid

spurious oscillations, and to make sure that the constraints do not

violate linear and angular momentum conservation. Additional position constraints

can be applied, for example to keep the nodes within desired regions of space

(sufficiently close to an animated model for example), or to maintain the body's

overall shape via shape matching.

Collision detection for deformable objects

Collision detection

Realistic interaction of simulated soft objects with their environment may be

important for obtaining visually realistic results. Cloth self-intersection is important in

some applications for acceptably realistic simulated garments. This is challenging to

achieve at interactive frame rates, particularly in the case of detecting and resolving

self collisions and mutual collisions between two or more deformable objects.

Collision detection may be discrete/a posteriori (meaning objects are advanced in

time through a pre-determined interval, and then any penetrations detected and

resolved), orcontinuous/a priori (objects are advanced only until a collision occurs,

and the collision is handled before proceeding). The former is easier to implement

and faster, but leads to failure to detect collisions (or detection of spurious collisions)

if objects move fast enough. Real-time systems generally have to use discrete

collision detection, with other ad hoc ways to avoid failing to detect collisions.

Detection of collisions between cloth and environmental objects with a well defined

"inside" is straightforward since the system can detect unambiguously whether the

cloth mesh vertices and faces are intersecting the body and resolve them

accordingly. If a well defined "inside" does not exist (e.g. in the case of collision with

a mesh which does not form a closed boundary), an "inside" may be constructed via

extrusion. Mutual- or self-collisions of soft bodies defined by tetrahedra is

straightforward, since it reduces to detection of collisions between solid tetrahedra.

However, detection of collisions between two polygonal cloths (or collision of a cloth

with itself) via discrete collision detection is much more difficult, since there is no

Page 27

unambiguous way to locally detect after a time step whether a cloth node which has

penetrated is on the "wrong" side or not. Solutions involve either using the history of

the cloth motion to determine if an intersection event has occurred, or doing a global

analysis of the cloth state to detect and resolve self-intersections. Pixar has

presented a method which uses a global topological analysis of mesh intersections

in configuration space to detect and resolve self-interpenetration of cloth. Currently,

this is generally too computationally expensive for real-time cloth systems.

To do collision detection efficiently, primitives which are certainly not colliding must

be identified as soon as possible and discarded from consideration to avoid wasting

time. To do this, some form of spatial subdivision scheme is essential, to avoid a

brute force test of O[n2] primitive collisions. Approaches used include:

Bounding volume hierarchies (AABB trees, OBB trees, sphere trees)

Grids, either uniform (using hashing for memory efficiency) or hierarchical

(e.g. Octree, kd-tree)

Coherence-exploiting schemes, such as sweep and prune with insertion sort, or

tree-tree collisions with front tracking.

Hybrid methods involving a combination of various of these schemes, e.g. a

coarse AABB tree plus sweep-and-prune with coherence between colliding

leaves.

Other effects which may be simulated via the methods of soft-body dynamics are:

Destructible materials: Fracture of brittle solids, cutting of soft bodies,

and tearing of cloth. The finite element method is especially suited to modelling

fracture as it includes a realistic model of the distribution of internal stresses in

the material, which physically is what determines when fracture occurs, according

to fracture mechanics.

Plasticity (permanent deformation) and melting

Simulated hair, fur, and feathers

Simulated organs for biomedical applications

Simulation of fluids in the context of computer graphics would not normally be

considered soft-body dynamics, which is usually restricted to mean simulation of

Page 28

materials which have a tendency to retain their shape and form. In contrast,

a fluid assumes the shape of whatever vessel contains it, as the particles are bound

together by relatively weak forces.

Rigid body dynamics

In physics, rigid body dynamics is the study of the motion of rigid bodies.

Unlike particles, which move only in three degrees of freedom (translation in three

directions), rigid bodies occupy space and have geometrical properties, such as

a centre of mass, moments of inertia, etc., that characterize motion in six degrees of

freedom (translation in three directions plus rotation in three directions). Rigid bodies

are also characterized as being non-deformable, as opposed to deformable bodies.

As such, rigid body dynamics is used heavily in analyses and computer

simulations of physical systems and machinery where rotational motion is important,

but material deformation does not have a significant effect on the motion of the

system.

Rigid body linear momentum

Newton's Second Law states that the rate of change of the linear momentum of a

particle with constant mass is equal to the sum of all external forces acting on the

particle:

where m is the particle's mass, v is the particle's velocity, their product mv is the

linear momentum, and fi is one of the N number of forces acting on the particle.

Because the mass is constant, this is equivalent to

Page 29

To generalize, assume a body of finite mass and size is composed of such particles,

each with infinitesimal mass dm. Each particle has a position vector r. There exist

internal forces, acting between any two particles, and external forces, acting only on

the outside of the mass. Since velocity v is the derivative of position r, the derivative

of velocity dv/dt is the second derivative of position d2r/dt2, and the linear momentum

equation of any given particle is

When the linear momentum equations for all particles are added together, the

internal forces sum to zero according to Newton's third law, which states that any

such force has opposite magnitudes on the two particles. By accounting for all

particles, the left side becomes an integral over the entire body, and the second

derivative operator can be moved out of the integral, so

.

Let M be the total mass, which is constant, so the left side can be multiplied and

divided by M, so

.

The expression   is the formula for the position of the centre of mass.

Denoting this by rcm, the equation reduces to

Thus, linear momentum equations can be extended to rigid bodies by denoting that

they describe the motion of the centre of mass of the body. This is known as Euler's

first law.

Rigid body angular momentum

Page 30

The most general equation for rotation of a rigid body in three dimensions about an

arbitrary origin O with axes x, y, z is

where the moment of inertia tensor,  , is given by

Given that Euler's rotation theorem states that there is always an instantaneous axis

of rotation, the angular velocity,  , can be given by a vector over this axis

where   is a set of mutually perpendicular unit vectors fixed in a reference

frame.

Rotating a rigid body is equivalent to rotating a Poinsot ellipsoid.

Angular momentum and torque

Similarly, the angular momentum   for a system of particles with linear

momenta pi and distances ri from the rotation axis is defined

For a rigid body rotating with angular velocity ω about the rotation axis   (a unit

vector), the velocity vector   may be written as a vector cross product

Where angular velocity vector 

 is the shortest vector from the rotation axis to the point mass.

Substituting the formula for   into the definition of   yields

Page 31

Where we have introduced the special case that the position vectors of all particles

are perpendicular to the rotation axis (e.g., a flywheel):  .

The torque   is defined as the rate of change of the angular momentum 

If I is constant (because the inertia tensor is the identity, because we work in the

intrinsically frame, or because the torque is driving the rotation around the same

axis   so that I is not changing) then we may write

Where α is called the angular acceleration (or rotational acceleration) about the

rotation axis .

Notice that if I is not constant in the external reference frame (i.e. the three main

axes of the body are different) then we cannot take the I outside the derivate. In

these cases we can havetorque-free precession.

Applications

Computer physics engines use rigid body dynamics to increase interactivity and

realism in video games.

No index entries found.Use of advanced computer graphics in architectural draughting.

AUTOCAD

AutoCAD is a CAD (Computer Aided Design or Computer Aided Drafting) software

application for 2D and 3D design and drafting. It is developed and sold by Autodesk,

Inc. First released in December 1982, AutoCAD was one of the first CAD programs

to run on personal computers, notably the IBM PC. At that time, most other CAD

programs ran on mainframe computers or mini-computers which were connected to

Page 32

a graphics computer terminal for each user. AutoCad and its vertical products are

incompatible with Bit Defender security software.

Early releases of AutoCAD used primitive entities — lines, poly lines, circles, arcs,

and text — to construct more complex objects. Since the mid-1990s, AutoCAD has

supported custom objects through its C++ Application Programming Interface (API).

Modern AutoCAD includes a full set of basic solid modelling and 3D tools. With the

release of AutoCAD 2007 came improved 3D modelling, which meant better

navigation when working in 3D. Moreover, it became easier to edit 3D models.

The mental ray engine was included in rendering, it was now possible to do quality

renderings. AutoCAD 2010 introduced parametric functionality and mesh modelling.

AutoCAD supports a number of APIs for customization and automation. These

include AutoLISP, Visual LISP, VBA, .NET and Object ARX. Object ARX is a C+

+ class library, which was also the base for products extending AutoCAD

functionality to specific fields, to create products such as AutoCAD Architecture,

AutoCAD Electrical, AutoCAD Civil 3D, or third-party AutoCAD-based applications.

AutoCAD and AutoCAD LT are available

for English, German, French, Italian, Spanish, Japanese, Korean, Chinese

Simplified, Chinese Traditional, Russian, Czech, Polish, Hungarian, Brazilian

Portuguese, Danish, Dutch, Swedish, Finnish, Norwegian, and Vietnamese. The

extent of localization varies from full translation of the product to documentation only.

The AutoCAD command set is localized as a part of the software localization.

AutoCAD origin

AutoCAD was derived from a program called Interact, which was written in a

proprietary language (SPL) and ran on the Marinchip Systems 9900 computer

(Marinchip was owned by Autodesk co-founders John Walker and Dan Drake.)

When Marinchip Software Partners (later to be renamed Autodesk) was formed, they

decided to re-code Interact in C and PL/1 -- C, because it seemed to be the biggest

upcoming language, and PL/1. In the end, the PL/1 version was unsuccessful. The C

version was, at the time, one of the most complex programs in that language to date.

Page 33

Autodesk even had to work with the compiler developer (Lattice) to fix certain

limitations to get AutoCAD to run.

AutoCAD LT

AutoCAD LT is a lower cost version of AutoCAD with reduced capabilities first

released in November 1993. AutoCAD LT, priced at $495, became the first product

in the company's history priced below $1000 to bear the name "AutoCAD". In

addition to being sold directly by Autodesk, it can also be purchased at computer

stores, unlike the full version of AutoCAD which must be purchased from official

Autodesk dealers. Autodesk developed AutoCAD LT so that they would have an

entry-level CAD package to compete in the lower price level.

As of the 2011 release the AutoCAD LT MSRP has risen to $1200. While there are

hundreds of small differences between the full AutoCAD package and AutoCAD LT,

currently there are a few recognized major differences in the software's features:

3D Capabilities: AutoCAD LT lacks the ability to create, visualize and render 3D

models as well as 3D printing.

Network Licensing: AutoCAD LT cannot be used on multiple machines over a

network.

Customization: AutoCAD LT does not support customization with LISP, ARX, and

VBA.

Management and automation capabilities with Sheet Set Manager and Action

Recorder.

CAD standards management tools.

AutoCAD Freestyle

Built on the AutoCAD platform, AutoCAD Freestyle is a simplified, low-cost (US$149)

application that makes it easy to create accurate, professional-looking 2D drawings

and sketches.

Student versions

Page 34

AutoCAD is licensed at a significant discount over commercial retail pricing to

qualifying students and teachers, with a 36-month license available. The student

version of AutoCAD is functionally identical to the full commercial version, with one

exception: DWG files created or edited by a student version have an internal bit-flag

set (the "educational flag"). When such a DWG file is printed by any version of

AutoCAD (commercial or student), the output will include a plot stamp / banner on all

four sides. Objects created in the Student Version cannot be used for commercial

use. These Student Version objects will "infect" a commercial version DWG file if

imported.

The Autodesk student community provides registered students with free access to

different Autodesk applications.

Vertical programs

Autodesk has also developed a few vertical programs, for discipline-specific

enhancements. AutoCAD Architecture (formerly Architectural Desktop), for example,

permits architectural designers to draw 3D objects such as walls, doors and

windows, with more intelligent data associated with them, rather than simple objects

such as lines and circles. The data can be programmed to represent specific

architectural products sold in the construction industry, or extracted into a data file

for pricing, materials estimation, and other values related to the objects represented.

Additional tools allow designers to generate standard 2D drawings, such as

elevations and sections, from a 3D architectural model. Similarly, Civil Design, Civil

Design 3D, and Civil Design Professional allow data-specific objects to be used,

allowing standard civil engineering calculations to be made and represented

easily. AutoCAD Electrical, AutoCAD Civil 3D, AutoCAD Map 3D, AutoCAD

Mechanical, AutoCAD MEP, AutoCAD P&ID, AutoCAD Plant 3D and AutoCAD

Structural detailing are other examples of industry-specific CAD applications built on

the AutoCAD platform.

AutoCAD Architecture

Page 35

AutoCAD Architecture (abbreviated as ACA) is a version of Autodesk's flagship

product, AutoCAD, with tools and functions specially suited to architectural work.

Architectural objects have a relationship to one another and interact with each other

intelligently. For example, a window has a relationship to the wall that contains it. If

you move or delete the wall, the window reacts accordingly. Objects can be

represented in both 2D and 3D.

In addition, intelligent architectural objects maintain dynamic links with construction

documents and specifications, resulting in more accurate project deliverables. When

someone deletes or modifies a door, for example, the door schedule can be

automatically updated. Spaces and areas update automatically when certain

elements are changed, calculations such as square footage are always up to date.

AutoCAD Architecture uses the DWG file format but an object enabler is needed to

access, display, and manipulate object data in applications different from AutoCAD

Architecture.

AutoCAD Architecture was formerly known as AutoCAD Architectural Desktop (often

abbreviated ADT) but Autodesk changed its name for the 2008 edition. The change

was made to better match the names of Autodesk's other discipline-specific

packages, such as AutoCAD Electrical and AutoCAD Mechanical.

Autodesk Maya

Maya was originally a next-generation animation product under development at Alias

Research, Inc. based on code from a previous Alias product, Alias Sketch!, a 3D

modeler and renderer for the Macintosh that lacked animation features. The code

was ported to IRIX and animation features were added. The codename for this

porting project was Maya.[4] Walt Disney Feature Animation collaborated closely with

Maya's development during its production of Dinosaur.[5] Disney requested that

the User interface of the application be customizable so that a personalized workflow

could be created. This was a particular influence in the open architecture of Maya,

and partly responsible for it's becoming so popular in the industry.

After Silicon Graphics Inc. acquired both Alias and Wavefront Technologies, Inc.,

Wavefront's next-generation technology (then under development) was merged into

Page 36

Maya. SGI's acquisition was a response to Microsoft

Corporation acquiring Softimage, Co.. The new wholly-owned subsidiary was named

"Alias Wavefront”.

In the early days of development, Maya started with Tcl as the scripting language, in

order to leverage its similarity to a Unix shell language. But after the merger with

Wavefront Sophia, the scripting language in Wavefront's Dynamation, was chosen

as the basis of MEL (Maya embedded language).

Maya 1.0 was released in February 1998. Alias was successful in expanding its

market share, with leading visual effects companies such as Industrial Light and

Magic and Tippett Studio switching from SoftImage to Maya.

Following a series of acquisitions, Maya was bought by Autodesk in 2005. Under the

name of the new parent company, Maya was renamed Autodesk Maya. However,

the name "Maya" continues to be the dominant name used for the product.

Awards

On February 8, 2008 Duncan Brinsmead, Jos Stam, Julia Pakalns and Martin

Werner received an Academy Award for Technical Achievement for the design and

implementation of the Maya Fluid Effects system.[11][12]

Overview

Maya is an application used to generate 3D assets for use in film, television, game

development and architecture. The software was initially released for the IRIX

operating system, however this support was discontinued in August 2006 after the

release of version 6.5. Maya was available in both "Complete" and "Unlimited"

editions until August 2008, when it was turned into a single suite. [13]

Users define a virtual workspace (scene) to implement and edit media of a particular

project. Scenes can be saved in a variety of formats, the default being .mb (Maya

Binary). Maya exposes a node graph architecture. Scene elements are node-based,

each node having its own attributes and customization. As a result, the visual

representation of a scene is based entirely on a network of interconnecting nodes,

depending on each others information. For the convenience of viewing these

networks, there is a dependency and a directed acyclic graph.

Page 37

Components

Since its consolidation from two distinct packages, Maya and later contain all the

features of the now defunct Unlimited suites.

Fluid Effects

A realistic fluid simulator (effective for smoke, fire, clouds and explosions, added in

Maya 4.5)

Classic Cloth

Cloth simulation to automatically simulate clothing and fabrics moving realistically

over an animated character. The Maya Cloth toolset has been upgraded in every

version of Maya released after Spider-Man 2. Alias worked with Sony Pictures

Imageworks to get Maya Cloth up to scratch for that production, and all those

changes have been implemented, although the big studios opted to use third party

plugins such as Syflex instead of the (relatively) cumbersome Maya Cloth.

Fur

Animal fur simulation similar to Maya Hair. It can be used to simulate other fur-like

objects, such as grass.

Hair

A simulator for realistic-looking human hair implemented using curves and Paint

Effects. These are also known as dynamic curves.

Maya Live

A set of motion tracking tools for CG matching to clean plate footage.

nCloth

Added in version 8.5, nCloth is the first implementation of Maya Nucleus, Autodesk's

simulation framework. nCloth gives the artist further control of cloth and material

simulations.

Page 38

nParticle

Added in version 2009, nParticle is addendum to Maya Nucleus toolset. nParticle is

for simulating a wide range of complex 3D effects, including liquids, clouds, smoke,

spray, and dust.

MatchMover

Added to Maya 2010, this enables compositing of CGI elements with motion data

from video and film sequences.

Composite

Added to Maya 2010, this was earlier sold as Autodesk Toxik.

Camera Sequencer

Added after Maya unlimited 2009, Camera Sequencer is used to layout multiple

camera shots and manage them in one animation sequence.

Maya Embedded Language

Alongside its more recognized visual workflow, Maya is equipped with its very own

cross-platform scripting language, fittingly called Maya Embedded Language. MEL,

as it is often shortened to, is provided not only for scripting, but also as a means to

customize the core functionality of the software, since much of the tools and

commands used are written in it. Code can be used to engineer modifications,  plug-

ins or be injected into runtime. Outside these superficial uses of the language, user

interaction is recorded in MEL, allowing even inexperienced users to

implement subroutines. Scene information can thus be dumped, extension .ma,

editable outside Maya in any text editor.

System requirements

Operating systems

Autodesk supports the Windows and Mac platforms; XP SP3 or later respectively. As

of Maya 2011, the software is 64-bit under Mac OS X. [14] While Autodesk

Page 39

acknowledges that the application is not limited to the aforementioned releases, such

as the specific Linux distribution,[15], it does not support them.

Autodesk Revit

Revit is a Building Information Modelling software for Microsoft Windows, developed

by Autodesk. It allows the user to design with both parametric 3D modelling and 2D

drafting elements. Building Information Modelling is a Computer Aided Design (CAD)

paradigm that employs intelligent 3D objects to represent real physical building

components such as walls and doors.

In addition, Revit's database for a project can contain information about a project at

various stages in the building's lifecycle, from concept to construction to

decommissioning. This is sometimes called 4D CAD where time is the fourth

dimension.

Autodesk purchased the Massachusetts-based Revit Technology Corporation for

US$133 million in 2002.[1]

The latest released version is Revit Architecture/Structure/MEP 2011 (April, 2010)[2] and the corresponding AutoCAD Revit Suite 2011 products. (AutoCAD Revit Suite

combines a seat of AutoCAD with a seat of Revit on a given workstation for a slightly

higher price than Revit alone.) On September 29, 2008, Autodesk released 64-bit

versions of Revit 2009 products for subscription customers. Both 32-bit and 64-bit

versions of Revit 2010 and 2011 products are available without subscription in the

standard installation. Revit is localized into multiple languages, including German,

French, Italian, Spanish, Czech, Polish, Hungarian and Russian.

Revit uses .RVT files for storing BIM models. Typically, a building is made using 3D

objects to create walls, floors, roofs, structure, windows, doors and other objects as

needed. These parametric objects — 3D building objects (such as windows or doors)

or 2D drafting objects (such as surface patterns) — are called "families" and are

saved in .RFA files, and imported into the RVT database as needed.

A Revit model is a single database file represented in the various ways which are

useful for design work. Such representations can be plans, sections, elevations,

Page 40

legends, and schedules. Because changes to each representation of the database

model are made to one central model, changes made in one representation of the

model (for example a plan) are propagated to other representations of the model (for

example elevations). Thus, Revit drawings and schedules are always fully

coordinated in terms of the building objects shown in drawings.

When a project database is shared, a central file is created which stores the master

copy of the project database on a file server on the office's LAN. Each user works on

a copy of the central file (known as the local file), stored on the user's workstation.

Users then save to the central file to update the central file with their changes and to

receive changes from other users. Revit checks with the central file whenever a user

starts working on an object in the database to see if another user is editing the

object. This procedure prevents two users from making the same change

simultaneously and prevents conflicts.

Multiple disciplines working together on the same project make their own project

databases and link in the other consultants' databases for verification. Revit can

perform collision checking, which detects if different components of the building are

occupying the same physical space. Revit is one of many BIM-software which

supports open XML-based IFC standard, developed by building

SMART organization. This filetype makes it possible for a client or general contractor

to require BIM-based workflow from the different discipline consultants of a building

project. Because IFC is non-proprietary format it is archivable and compatible with

other databases, such as facility management software.

Modelling

Revit uses a similar work environment to Inventor to create its 3D models, allowing

users to extrude, revolve, trace the path of, or morph shapes drawn on a 3D plane in

order to make them into 3D objects, as well as do these actions to already made

solid objects to cut or reform them. However, Revit lacks the ability to allow the user

to manipulate the object's individual polygons.

As simple or primitive as this may seem, an experienced user can create realistic

and accurate models of objects, as well as import premade models from other

Page 41

programs. This also ensures that the generative components of an object are

retained so they can be parametrically controlled. Revit families can be created with

dimensions controlled by parameters (parametric). This allows users to modify the

component by changing predefined values such as height and width.

Intended use

Revit is intended to be a major component in Building Information Modelling. A main

function of Revit is to eliminate redundancies such as having multiple models across

industries. Currently, architects, consultants, general contractors, and manufacturers

all create their own models and databases from information handed down in a chain

of command. BIM intends to replace this approach with a more centralized one.

Revit models created in different disciplines (Architectural, Structural, and

Mechanical) can be linked and/or combined into one model. This allows a single

model and associated database to be kept, ensuring that all parties have the latest

information and that there are no errors in translation. Revit also utilizes its rendering

engine to remove the interpretation from complex geometries, allowing more intricate

designs to be made and understood.

Family based content

Revit uses the term 'family' to describe a discrete definition of a part of the building

model. There are many Categories of Families, but three main types: System,

Component and In-Place Families. Where other programs may use terms such as

'block' or 'insert', Revit uses the term 'Family'.

A hierarchical system is used, where a Family tells Revit how to make something, a

Type (of a Family) forces certain parameters to be applied, and an Element (or

Instance) (of a Type) is the actual part of the building model. For example, a Swing

Door may be the name of a Family. It may have Types describing different sizes, and

the actual building model will have instances of those types placed in Walls.

Rendering

Page 42

When a user makes a building, room, model, or any other kind of object in Revit, she

or he may use Revit's rendering engine to make a very realistic image of what is

otherwise a very diagrammatic model. This is accomplished by either using the

premade model, wall, floor, etc., tools, or making her or his own models, walls,

materials, etc.. The wall- and model- making process is simple enough to pick up in

a day or so. Revit 2010 comes with a plethora of premade materials, each of which

can be modified to the user's desires. The user can also begin with a "Generic"

material, which can be customized to a level of detail not offered by many 3D

modeling programs. With this, the user can set the rotation, size, brightness, and

intensity of textures, gloss maps (also known as shinemaps), transparency maps,

reflection maps, oblique reflection maps, hole maps, and bump maps, as well as

leaving the map part out and just using the sliders for any one (or all or none) of the

aforementioned features of textures. To the right is an example of what can be

accomplished when an experienced user implements all the techniques listed in this

section, using only Revit.

Autodesk 3ds Max

Autodesk 3ds Max, formerly 3D Studio MAX, is a modeling, animation and

rendering package developed by Autodesk Media and Entertainment. It has

modeling capabilities, a flexible plugin architecture and can be used on the Microsoft

Windows platform. It's frequently used by video game developers, TV commercial

studios and architectural visualization studios. It is also used for movie effects and

movie pre-visualization.

In addition to its modeling and animation tools, the latest version of 3ds Max also

features shaders (such as ambient occlusion and subsurface scattering), dynamic

simulation, particle systems, radiosity, normal map creation and rendering, global

illumination, a customizable user interface, and its own scripting language.

The original 3D Studio product was created for the DOS platform by the Yost Group

and published by Autodesk. After 3D Studio Release 4, the product was rewritten for

the Windows NT platform, and re-named "3D Studio MAX." This version was also

originally created by the Yost Group. It was released by Kinetix, which was at that

Page 43

time Autodesk's division of media and entertainment. Autodesk purchased the

product at the second release mark of the 3D Studio MAX version and internalized

development entirely over the next two releases. Later, the product name was

changed to "3ds max" (all lower case) to better comply with the naming conventions

of Discreet, a Montreal-based software company which Autodesk had purchased. At

release 8, the product was again branded with the Autodesk logo, and the name was

again changed to "3ds Max" (upper and lower case). At release 2009, the product

name changed to "Autodesk 3ds Max".

Features

MAXScript

MAXScript is a built-in scripting language, and can be used to automate repetitive

tasks, combine existing functionality in new ways, develop new tools and user

interfaces and much more. Plugin modules can be created entirely in MAXScript.

Character Studio

Character Studio was a plugin which since version 4 of Max is now integrated in 3D

Studio Max, helping user to animate virtual characters. The system works using a

character rig or "Biped" which is pre-made and allows the user to adjust the rig to fit

the character they will be animating. Dedicated curve editors and motion capture

data import tools make Character Studio ideal for character animation. "Biped"

objects have other useful features that automated the production of walk cycles and

movement paths, as well as secondary motion.

Scene Explorer

Scene Explorer, a tool that provides a hierarchical view of scene data and analysis,

facilitates working with more complex scenes. Scene Explorer has the ability to sort,

filter, and search a scene by any object type or property (including metadata). Added

in 3ds Max 2008, it was the first component to facilitate .NET managed code in 3ds

Max outside of MAXScript.

DWG Import

Page 44

3ds Max supports both import and linking of DWG files. Improved memory

management in 3ds Max 2008 enables larger scenes to be imported with multiple

objects.

Texture Assignment/Editing

3ds Max offers operations for creative texture and planar mapping, including tiling,

mirroring, decals, angle, rotate, blur, UV stretching, and relaxation; Remove

Distortion; Preserve UV; and UV template image export. The texture workflow

includes the ability to combine an unlimited number of textures, a material/map

browser with support for drag-and-drop assignment, and hierarchies with thumbnails.

UV workflow features include Pelt mapping, which defines custom seams and

enables users to unfold UVs according to those seams; copy/paste materials, maps

and colors; and access to quick mapping types (box, cylindrical, spherical).

General Key-framing

Two keying modes — set key and auto key — offer support for different keyframing

workflows.

Fast and intuitive controls for key-framing — including cut, copy, and paste — let the

user create animations with ease. Animation trajectories may be viewed and edited

directly in the viewport.

Constrained Animation

Objects can be animated along curves with controls for alignment, banking, velocity,

smoothness, and looping, and along surfaces with controls for alignment. Weight

path-controlled animation between multiple curves, and animate the weight. Objects

can be constrained to animate with other objects in many ways — including look at,

orientation in different coordinate spaces, and linking at different points in time.

These constraints also support animated weighting between more than one target.

All resulting constrained animation can be collapsed into standard keyframes for

further editing.

Page 45

Skinning

Either the Skin or Physique modifier may be used to achieve precise control of

skeletal deformation, so the character deforms smoothly as joints are moved, even in

the most challenging areas, such as shoulders. Skin deformation can be controlled

using direct vertex weights, volumes of vertices defined by envelopes, or both.

Capabilities such as weight tables, paintable weights, and saving and loading of

weights offer easy editing and proximity-based transfer between models, providing

the accuracy and flexibility needed for complicated characters.

The rigid bind skinning option is useful for animating low-polygon models or as a

diagnostic tool for regular skeleton animation.

Additional modifiers, such as Skin Wrap and Skin Morph, can be used to drive

meshes with other meshes and make targeted weighting adjustments in tricky areas.

Skeletons and Inverse Kinematics (IK)

Characters can be rigged with custom skeletons using 3ds Max bones, IK solvers,

and rigging tools powered by Motion Capture Data.

All animation tools — including expressions, scripts, list controllers, and wiring —

can be used along with a set of utilities specific to bones to build rigs of any structure

and with custom controls, so animators see only the UI necessary to get their

characters animated.

Four plug-in IK solvers ship with 3ds Max: history-independent solver, history-

dependent solver, limb solver, and spline IK solver. These powerful solvers reduce

the time it takes to create high-quality character animation. The history-independent

solver delivers smooth blending between IK and FK animation and uses preferred

angles to give animators more control over the positioning of affected bones.

The history-dependent solver can solve within joint limits and is used for machine-

like animation. IK limb is a lightweight two-bone solver, optimized for real-time

interactivity, ideal for working with a character arm or leg. Spline IK solver provides a

flexible animation system with nodes that can be moved anywhere in 3D space. It

Page 46

allows for efficient animation of skeletal chains, such as a character’s spine or tail,

and includes easy-to-use twist and roll controls.

Integrated Cloth Solver

In addition to reactor’s cloth modifier, 3ds Max software has an integrated cloth-

simulation engine that enables the user to turn almost any 3D object into clothing, or

build garments from scratch. Collision solving is fast and accurate even in complex

simulations.(image.3ds max.jpg)

Local simulation lets artists drape cloth in real time to set up an initial clothing state

before setting animation keys.

Cloth simulations can be used in conjunction with other 3ds Max dynamic forces,

such as Space Warps. Multiple independent cloth systems can be animated with

their own objects and forces. Cloth deformation data can be cached to the hard drive

to allow for non-destructive iterations and to improve playback performance.

Integration with Autodesk Vault

Autodesk Vault plug-in, which ships with 3ds Max, consolidates users’ 3ds Max

assets in a single location, enabling them to automatically track files and manage

work in progress. Users can easily and safely share, find, and reuse 3ds Max (and

design) assets in a large-scale production or visualization environment.

Modelling techniques

Polygon modelling

Polygon modelling is more common with game design than any other modelling

technique as the very specific control over individual polygons allows for extreme

optimization. Usually, the modeller begins with one of the 3ds max primitives, and

using such tools as bevel and extrude, adds detail to and refines the model. Versions

4 and up feature the Editable Polygon object, which simplifies most mesh editing

operations, and provides subdivision smoothing at customizable levels.

Page 47

Version 7 introduced the edit poly modifier, which allows the use of the tools

available in the editable polygon object to be used higher in the modifier stack (i.e.,

on top of other modifications)

NURBS or non-uniform rational B-spline

An alternative to polygons, it gives a smoothed out surface that eliminates the

straight edges of a polygon model. NURBS is a mathematically exact representation

of freeform surfaces like those used for car bodies and ship hulls, which can be

exactly reproduced at any resolution whenever needed. With NURBS, a smooth

sphere can be created with only one face.

The non-uniform property of NURBS brings up an important point. Because they are

generated mathematically, NURBS objects have a parameter space in addition to

the 3D geometric space in which they are displayed. Specifically, an array of values

called knots specifies the extent of influence of each control vertex (CV) on the curve

or surface. Knots are invisible in 3D space and you can't manipulate them directly,

but occasionally their behaviour affects the visible appearance of the NURBS object.

This topic mentions those situations. Parameter space is one-dimensional for curves,

which have only a single U dimension topologically, even though they exist

geometrically in 3D space. Surfaces have two dimensions in parameter space, called

U and V.

NURBS curves and surfaces have the important properties of not changing under

the standard geometric affine transformations (Transforms), or under perspective

projections. The CVs have local control of the object: moving a CV or changing its

weight does not affect any part of the object beyond the neighbouring CVs. (You can

override this property by using the Soft Selection controls.) Also, the control lattice

that connects CVs surrounds the surface. This is known as the convex hull property.

Surface tool/Editable patch object

Surface tool was originally a 3rd party plugin, but Kinetix acquired and included this

feature since version 3. The surface tool is for creating common 3ds Max splines,

and then applying a modifier called "surface." This modifier makes a surface from

every 3 or 4 vertices in a grid. This is often seen as an alternative to "mesh" or

Page 48

"nurbs" modelling, as it enables a user to interpolate curved sections with straight

geometry (for example a hole through a box shape). Although the surface tool is a

useful way to generate parametrically accurate geometry, it lacks the "surface

properties" found in the similar Edit Patch modifier, which enables a user to maintain

the original parametric geometry whilst being able to adjust "smoothing groups"

between faces.

Predefined primitives

This is a basic method, in which one models something using only boxes, spheres,

cones, cylinders and other predefined objects from the list of Predefined Standard

Primitives or a list of Predefined Extended Primitives. One may also apply boolean

operations, including subtract, cut and connect. For example, one can make two

spheres which will work as blobs that will connect with each other. These are

called metaballs.

Some of the 3ds Max Standard Primitives as they appear in the wireframe view of

3ds Max 9

Some of the 3ds Max Extended Primitives as they appear in the wireframe view of

3ds Max 9

Page 49

Predefined Standard Primitives list

Box — box produces a rectangular prism. An alternative variation of box is

available — entitled cube — which proportionally constrains the length, width and

height of the box.

Cylinder — cylinder produces a cylinder.

Torus — torus produces a torus — or a ring — with a circular cross section,

sometimes referred to as a doughnut.

Teapot — teapot produces the Utah teapot. Since the teapot is a parametric

object, the user can choose which parts of the teapot to display after creation.

These parts include the body, handle, spout and lid.

Cone — cone produces round cones — either upright or inverted.

Sphere — sphere produces a full sphere, hemisphere, or other portion of a

sphere.

Tube — tube can produce both round and prismatic tubes. The tube is similar to

the cylinder with a hole in it.

Pyramid — The pyramid primitive has a square or rectangular base and

triangular sides.

Plane — The plane object is a special type of flat polygon mesh that can be

enlarged by any amount at render time. The user can specify factors to magnify

the size or number of segments, or both. Modifiers such as displace can be

added to a plane to simulate a hilly terrain.

Geosphere — GeoSphere produces spheres and hemispheres based on three

classes of regular polyhedrons.

Predefined Extended Primitives list

Hedra — produces objects from several families of polyhedra..

ChamferBox — creates a box with beveled or rounded edges.

OilTank — creates a cylinder with convex caps.

Spindle — creates a cylinder with conical caps.

Page 50

Gengon — creates an extruded, regular-sided polygon with optionally filleted side

edges.

Prism — Creates a three-sided prism with independently segmented sides.

Torus knot — creates a complex or knotted torus by drawing 2D curves in the

normal planes around a 3D curve. The 3D curve (called the Base Curve) can be

either a circle or a torus knot. It can be converted from a torus knot object to a

NURBS surface.

ChamferCyl — creates a cylinder with beveled or rounded cap edges.

Capsule — creates a cylinder with hemispherical caps.

L-Ext — creates an extruded L-shaped object.

C-Ext — creates an extruded C-shaped object.

Hose — a flexible object, similar to a spring.

Rendering

Scanline rendering

The default rendering method in 3DS Max is scanline rendering. Several advanced

features have been added to the scanliner over the years, such as global

illumination, radiosity, andray tracing.

Mental ray

mental ray is a production quality renderer developed by mental images. It is

integrated into the later versions of 3ds Max, and is a powerful raytracing renderer

with bucket rendering, a technique that allows distributing the rendering task for a

single image between several computers efficiently, using TCP network protocol.

RenderMan

A third party connection tool to RenderMan pipelines is also available for those that

need to integrate Max into Renderman render farms.

V-Ray

Page 51

A third-party render engine plug-in for 3D Studio MAX. It is widely used, frequently

substituting the standard and mental ray renderers which are included bundled with

3ds Max. V-Ray continues to be compatible with older versions of 3ds Max.

Brazil R/S

A third-party high-quality photorealistic rendering system created by SplutterFish,

LLC capable of fast ray tracing and global illumination.

FinalRender

Another third-party raytracing render engine created by Cebas. Capable of

simulating a wide range of real-world physical phenomena.

Fryrender

A third party photorealistic, physically-based, unbiased and spectral renderer created

by RandomControl capable of very high quality and realism.

Arion Render

A third party hybrid GPU+CPU interactive, unbiased raytracer created by

RandomControl, based on NVIDIA CUDA.

Indigo Renderer

A third-party photorealistic renderer with plugins for 3ds max.

Maxwell Render

A third-party photorealistic rendering system created by Next Limit

Technologies providing robust materials and highly accurate unbiased rendering.

BIGrender 3.0

Page 52

Another third-party rendering plugin. Capable of overcoming 3DS rendering memory

limitations with rendering huge pictures.

Page 53

Rendering Edges in Google Sketchup

Rendering Mirror surface in 3ds max

Page 54

Rendering Window in 3ds Max

Rendered Image in 3ds Max

Page 55

Rendering using artificial lighting

Landscaping is a unique feature of Sun based source

Page 56