Unformatted text preview: roject onto the same area the hemisphere have the same form
project onto the same area ofof the hemisphere have the same form
factor
factor !
Direct computation of approximate
Direct computation of thethe
a factor equation factor equation
formpproximate formfor every pair of
for every pair of patches will be
patches will be expensive to compute.
expensive to compute. !
!
So an approximate computation method
So an approximate computation
based on this observation (the
method was developed.
hemicube) based on this observation
(the hemicube) was developed. ! !
Graphics Lecture 13: Slide 25! . 21 / 29 Thehe Hemicube method "
T Hemicube method
So, a patches hemisphere it can be shown that a patches that
Usingall boundingthat project onto the same area ofall surrounding
hemicube the approximately the same form factor. same form
project ontohavesame area of the hemisphere have the !
factor
!
The hemicube is preferred to the
Direct computation of the approximate
h factor equation computing
formemisphere sincefor every pair of
intersections with planes is
patches will be expensive to compute.
computationally less demanding ! So an approximate computation method
based on this observation (the
hemicube) was developed. Graphics Lecture 13: Slide 26! . 21 / 29 Delta form factors "
Delta form factors The hemicube is divided into small pixel areas and form
The computed for each. !
factors are hemicube is divided into small pixel areas and form factors are
computed for each. The resulting form factors can be be used for in the
The resulting form factors canused for every patchevery patch in
scene. We just ‘place’ the same hemicube over each.
the scene. We just ‘place’ the same hemicube over each. !
!
. 23 / 29 Graphics Lecture 13: Slide 27! Delta form factors Delta form factors"
• If the area of a hemicube pixel is A, its form factor is: !
If the area of a hemicube pixel is A, its form factor is:
cos i...
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 Spring '14
 Energy, Light, form factor, Rendering

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