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Definitions and Review

Radiosity:
Diffuse interaction of light
Radiance:
Electromagnetic energy flux, the amount of energy traveling
Spectral Properties:
Total energy flux comes from flux at each wavelength

Picture:
For the indicated situation is

Power:
Energy per unit time (as in the picture)
Radiosity:
Total power leaving a surface point per unit area
(integral is over the hemisphere above the surface point)

Bidirectional Reflectance Distribution Function:

Energy Balance Equation:

Radiosity Approach to Global Illumination:

Simple Energy Balance (Hemisphere Based):

Multiplying by and letting :

But, in general

So we let

for the appropriate point y.

Picture (Scene Based Energy Balance):

Visibility:

We use a term to pick out the special y

Area:

We convert to surface area

Simple Energy Balance (Scene Based):

Piecewise Constant Approximation:

Piecewise Constant Radiosity Approximation:

Form Factor:

Note, by symmetry, that we have

Linear Equations:
(by Summetry)

Radiosity:
(Summary)

Radiosity:
Full Matrix Solution

Advanced Radiosity:
Galerkin Method

Minimize Residual Function


next up previous
Next: Form Factors Up: Radiosity-based Global Illumination Previous: Radiosity-based Global Illumination

CS488/688: Introduction to Interactive Computer Graphics
University of Waterloo
Computer Graphics Lab

cs488@cgl.uwaterloo.ca