cse40166 (notre dame) computer graphics lecture 1 john h stewman 205c cushing 1-4528 [email protected]
TRANSCRIPT
CSE40166 (Notre Dame)Computer Graphics
Lecture 1
John H Stewman
205C Cushing
1-4528
Introduction
Who John H Stewman, PhD (instructor) Jim Thomas (TA)
Where Here and now
Syllabus Class Web site Lecture Schedule Assignment #1
Computer Graphics
Computer Graphics deals with all aspects of the production of pictures (images) using a computer
Hardware Software Applications
4Angel: Interactive Computer Graphics 5E © Addison-Wesley 2009
Example
Where did this image come from?
What hardware/software did we need to produce it?
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Preliminary Answer
Application: The object is an artist’s rendition of the sun for an animation to be shown in a domed environment (planetarium)
Software: Maya for modeling and rendering but Maya is built on top of OpenGL
Hardware: PC with graphics card for modeling and rendering
Some Application Categories
Information Display Floor plans, maps, data plots, CT/MRI/PET
Design CAD/CAM, VLSI layout
Simulation Pilot training, movie animation, virtual reality
User Interfaces Windows Desktop
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Basic Graphics System
Input devices
Output device
Image formed in FB
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Computer Graphics: 1950-1960
Computer graphics goes back to the earliest days of computing
Strip chartsPen plottersSimple displays using A/D converters to go from
computer to calligraphic CRTCost of refresh for CRT too high
Computers slow, expensive, unreliable
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Computer Graphics: 1960-1970
Wireframe graphicsDraw only lines
SketchpadDisplay ProcessorsStorage tube
wireframe representationof sun object
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Sketchpad
Ivan Sutherland’s PhD thesis at MITRecognized the potential of man-machine
interaction Loop
Display somethingUser moves light penComputer generates new display
Sutherland also created many of the now common algorithms for computer graphics
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Display Processor
Rather than have the host computer try to refresh display use a special purpose computer called a display processor (DPU)
Graphics stored in display list (display file) on display processor
Host compiles display list and sends to DPU
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Computer Graphics: 1970-1980
Raster GraphicsBeginning of graphics standards
GKS: European effortGraphical Kernel SystemBecomes ISO 2D standard
Core: North American effort 3D but fails to become ISO standard
Workstations and PCs
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Raster Graphics
Image produced as an array (the raster) of picture elements (pixels) in the frame buffer
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Raster Graphics
Allows us to go from lines and wire frame images to filled polygons
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PCs and Workstations
Although we no longer make the distinction between workstations and PCs, historically they evolved from different roots
Early workstations characterized byNetworked connection: client-server modelHigh-level of interactivity
Early PCs included frame buffer as part of user memory
Easy to change contents and create images
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Computer Graphics: 1980-1990
Realism comes to computer graphics
smooth shading environment mapping
bump mapping
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Computer Graphics: 1980-1990
Special purpose hardwareSilicon Graphics geometry engine
VLSI implementation of graphics pipeline
Industry-based standardsPHIGSRenderMan
Networked graphics: X Window SystemHuman-Computer Interface (HCI)
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Computer Graphics: 1990-2000
OpenGL APICompletely computer-generated feature-length movies (Toy Story) are successful
New hardware capabilitiesTexture mappingBlendingAccumulation, stencil buffers
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Computer Graphics: 2000-today
PhotorealismGraphics cards for PCs dominate market
Nvidia, ATIGame boxes and game players determine direction of market
Computer graphics routine in movie industry: Maya, Lightwave
Programmable pipelines
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Elements of Image Formation
ObjectsViewerLight source(s)
Attributes that govern how light interacts with the materials in the scene
Note the independence of the objects, the viewer, and the light source(s)
Pixels & Frame Buffers
Raster Array of pixels
Pixel Picture element
Fragment Potential pixel
Frame buffer Memory store of pixel data Depth, Resolution, …
Images
Points Location on an object in reference space
Cartesian Coordinates Perpendicular axes, equal scales
Objects Metric and topological specification
Vertices Carry metric information (the corners of things)
Vertex listings Identify boundaries of faces, objects (the topology)
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Light
Light is the part of the electromagnetic spectrum that causes a reaction in our visual systems
Generally these are wavelengths in the range of about 350-750 nm (nanometers)
Long wavelengths appear as reds and short wavelengths as blues
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Ray Tracing and Geometric Optics
Follow rays of light from a point
source, detecting interactions
with objects, and find which
rays enter the lens of the
camera.
• Rays• Reflections (specular & diffuse)• Refractions & Absorptions
Thanks to …
Many slides in this presentation have been used from Edward Angel’s PowerPoint lectures at UMN.
In some cases slides have been modified to suit this class
Any errors or omissions may be attributed to J H Stewman