Lecture 13 - Radiosity I

21 29 thehe hemicube method t hemicube method so a

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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. hemi-cube) based on this observation (the hemi-cube) 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 hemi-cube) 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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