Traditional Radiosity

1
Traditional Radiosity
Instant Radiosity

• Splits model up into patches
• Calculates diffuse lighting on scene by
  integrating light emitted by every patch onto
  every other patch.
• Only as good as how many patches you use.

• Starts with a hardware light and renders scene
  with shadows.
• Ray traces model from light and calculates new
  light points same color as surface intersected.
• Only as good as how many lights and bounces you
  use.

2
Pseudo Code

• Draw the scene with shadows.
• Ray trace the scene to determine the appropriate
  number of new child light sources.
• Each is attenuated by the surface color and light
  absorption information.
• Draw scene with shadows from each child light.
• Repeat step 2 using child light to generate
  further lights.
• Combine all images together for final result.

3
Monte-Carlo Rays
Multiple rays spawned per child light
Single ray spawned per child light
4
Actual Images
Actual Image of Modeled Scene
Single Ray Monte-Carlo
Multiple Rays Monte-Carlo
Time For 1 Frame 9 seconds
10 seconds
200 lights
800 lights
5
Problems

• Shadows, shadows, shadows
• Getting working initially.
• Getting to work with desired field-of-view.
• Cleaning up z-fighting noise.
• Getting to work in GLSL.
• Determining proper blending of individual scenes.
• Ray tracing the image properly.
• Hopes dashed for one of my optimizations.
• Render individual images to pbuffers.
• Not enough pbuffer space.
• Not enough texture units.

PITN
PITN
6
Improvements that can still be made

• Generating new lights based on shadow-map
  information.
• Still have to take each face of cube map into
  account.
• Use a paraboloid shadow-map.
• Use non floating-point pbuffers when rendering.
• Use EXT_framebuffer extension when its created.

7
Questions ???
Questions ???