Visualization and Simulation Caio Brito Summary Local Illumination - - PowerPoint PPT Presentation

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Visualization and Simulation Caio Brito Summary Local Illumination - - PowerPoint PPT Presentation

Nov 07, 2023 40 likes •653 views

Visualization and Simulation Caio Brito Summary Local Illumination Graphical pipeline Illumination model Shader Global Illumination Ray Tracing Path tracing Physics based simulation Fluids Rigid

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Visualization and Simulation

Caio Brito

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Summary

  • Local Illumination

– Graphical pipeline – Illumination model – Shader

  • Global Illumination

– Ray Tracing – Path tracing

  • Physics based simulation

– Fluids – Rigid Body – Position-Based

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Local Illumination

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Local Illumination :: Graphical Pipeline

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Local Illumination :: Graphical Pipeline

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Local Illumination :: Illumination Model

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Local Illumination :: Illumination Model

  • Ambient

– Simple way of modeling indirect reflection. Ia: Ambient light intensity Ka: Ambient constant

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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.

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Local Illumination :: Illumination Model

  • Diffuse

– Smaller angle > Bigger cosine > More intensity.

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Local Illumination :: Illumination Model

  • Specular

– Simulates a highlight. – Reflection angle = incident angle.

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Local Illumination :: Illumination Model

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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.

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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.

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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.

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Local Illumination :: Illumination Model

Position-Normal Distributions for Efficient Rendering of Specular Microstructure

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Local Illumination :: Illumination Model

Physically-Accurate Fur Reflectance: Modeling, Measurement and Rendering

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Local Illumination :: Illumination Model

Discrete Stochastic Microfacet Models

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Local Illumination :: Shader

  • A Shader is a user-defined program designed to run
  • n 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/
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Local Illumination :: Shader

  • Vertex Shader
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Local Illumination :: Shader

  • Fragment Shader
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Local Illumination :: Shader

  • Fragment Shader
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Local Illumination

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Global Illumination

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Global Illumination

  • Local Illumination
  • Global Illumination
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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

  • Primary Rays

– Primary rays are rays from the viewpoint to the nearest intersection point. – Local illumination is computed:

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Global Illumination :: Ray Tracing

  • Secondary Rays

– Reflection Ray

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Global Illumination :: Ray Tracing

  • Secondary Rays

– Refraction Ray

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Global Illumination :: Ray Tracing

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Global Illumination :: Ray Tracing

  • Limitation
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Global Illumination :: Ray Tracing

  • Limitation
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Global Illumination :: Path Tracing

  • Trace multiple rays from a single pixel
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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
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Global Illumination :: Path Tracing

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Global Illumination :: Path Tracing

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Global Illumination :: Path Tracing

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Which Realism?

  • Photorealism

– image produces the same visual response as the scene

  • Functional realism

– Image provides the same visual information as the scene

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Which Realism?

  • Photorealism
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Which Realism?

  • Functional realism
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Physics Based Simulation

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Physics Based Simulation :: Fluid Simulation

  • Smoothed Particle Hydrodynamics

– Solve Navier-Stokes equation – Finite number of particles

  • Position, velocity, mass, density, viscosity and influence radius
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Physics Based Simulation :: Fluid Simulation

  • Smoothed Particle Hydrodynamics
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Physics Based Simulation :: Fluid Simulation

  • Smoothed Particle Hydrodynamics
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Physics Based Simulation :: Fluid Simulation

  • Smoothed Particle Hydrodynamics
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Physics Based Simulation :: Fluid Simulation

  • Smoothed Particle Hydrodynamics
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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
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Physics Based Simulation :: Rigid Body Dynamics

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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)

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Physics Based Simulation :: Position-Based Dynamics

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Physics Based Simulation

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Visualization and Simulation

Caio Brito