Radiosity

Question 1

Classical Radiosity Formulation

Answer 1

Use radiosities instead of radiance and assume that surfaces are diffuce reflectors and compute form factors for them.

Question 2

Form Factor

Answer 2

How one patch sees another. The fraction of radiation power that leaves patch 1 and arrives at patch 2.

Question 3

4 Ways to compute form factors

Answer 3

1. Contour Integration
2. Gaussian Quadrature
3. Hemicube
4. Monte Carlo Ray Casting

(1-3) Deterministic
4 Non-deterministic

Question 4

Radiosity via ray tracing

Answer 4

Calculate shooting power by picking a shooting patch and sending out rays from that patch into the environment. Requires shooting in a specific distribution.

Paper: Shirley, 1990 “Illumination Calculation”

Question 5

Newmann Series

Answer 5

[?] Radiant power is a recursive function of emittance and form factors of reflected surfaces.

Question 6

Radiosity vs Ray Tracing

Answer 6

+ Radiosity:

1. Excellent eval of indirect illumination
2. Good for soft shadows
3. Good colour bleeding

• Radiosity
  1. Weak handling of specular/high frequency signals