L is the radiance from a point on a surface in a given direction
_
E is the emitted radiance from a point: E is non-zero only if x’ is emissive
V is the visibility term: 1 when the surfaces are unobstructed along the direction
_, 0 otherwise
G is the geometry term, which depends on the geometric relationship between
the two surfaces x and x’
Photon-tracing uses sampling and Monte-Carlo integration Radiosity
uses finite elements:
project onto a finite set of basis functions (piecewise constant)
Ray tracing computes L [D] S* E
Photon tracing computes L [D | S]* E
Radiosity only computes L [D]* E
