Download - Visualization and Simulation
Summary
• Local Illumination– Graphical pipeline– Illumination model– Shader
• Global Illumination– Ray Tracing– Path tracing
• Physics based simulation– Fluids– Rigid Body– Position-Based
Local Illumination :: Illumination Model
• Ambient– Simple way of modeling indirect reflection.
Ia: Ambient light intensity
Ka: Ambient constant
Local Illumination :: Illumination Model
• Diffuse– Ideal diffuse surface reflects light equally in all directions,
according to Lambert's cosine law.
– Lambert’s Cosine Law: amount of light energy that falls on surface and gets reflected is proportional to incidence angle.
Local Illumination :: Illumination Model
• Specular– Simulates a highlight.– Reflection angle = incident angle.
Local Illumination :: Illumination Model
• Flat Shading– Shades each polygon of an object based on the angle
between the polygon's surface normal and the direction of the light source.
Local Illumination :: Illumination Model
• Gouraud Shading– Calculates the surface normals for the polygons.– Lighting computations are then performed to produce
intensities at vertices.– These intensities are interpolated along the edges of the
polygons.
Local Illumination :: Illumination Model
• Phong Shading– Calculate the surface normals at the vertices of polygons in
a 3D computer model.– These normals are interpolated along the edges of the
polygons.– Lighting computations are then performed.
Local Illumination :: Illumination Model
Position-Normal Distributions for Efficient Rendering of Specular Microstructure
Local Illumination :: Illumination Model
Physically-Accurate Fur Reflectance: Modeling, Measurement and Rendering
Local Illumination :: Shader
• A Shader is a user-defined program designed to run on some stage of a graphics processor.
• Its purpose is to execute one of the programmable stages of the rendering pipeline.
• GLSL, HLSL, Cg, DirectX• Basic structure: Vertex Shader and Fragment Shader• http://antongerdelan.net/opengl/• https://learnopengl.com/• https://www.shadertoy.com/
Global Illumination :: Ray Tracing
• Primary Rays– Primary rays are rays from the viewpoint to the nearest
intersection point.– Local illumination is computed:
Global Illumination :: Path Tracing
• How to choose a secondary ray?• Each material have a Kd, Ks and Kt
– Let Ktot = Kd + Ks + Kt– Choose a random number R in the interval (0,Ktot)
• If (R < Ks), trace a diffuse ray• else if (R < Kd + Ks), trace a specular ray• else, trace a refraction ray
Which Realism?
• Photorealism – image produces the same visual response as the scene
• Functional realism– Image provides the same visual information as the scene
Physics Based Simulation :: Fluid Simulation
• Smoothed Particle Hydrodynamics– Solve Navier-Stokes equation– Finite number of particles
• Position, velocity, mass, density, viscosity and influence radius
Physics Based Simulation :: Fluid Simulation
• Smoothed Particle Hydrodynamics
Physics Based Simulation :: Fluid Simulation
• Smoothed Particle Hydrodynamics
Physics Based Simulation :: Fluid Simulation
• Smoothed Particle Hydrodynamics
Physics Based Simulation :: Rigid Body Dynamics
• Rigid bodies have a position and orientation• No deformation• The motion be represented by 2 parameters
– Center of mass– Orientation
• Force and Torque are computed
Physics Based Simulation :: Position-Based Dynamics
• Particles everywhere– Position, velocity, mass, phase
• Uses different constraints for each kind of simulation– Distance (clothing) – Shape (rigids, plastics) – Density (fluids)– Volume (inflatables)– Contact (non-penetration, friction)