Lecture 13 - Radiosity I

since the emitted light will not be constant across

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Unformatted text preview: so we need to collect the incident light in a specular cone to determine the specular reflection. ! •  This is computationally infeasible. ! •  We will return to specularities later, but for the moment we will consider only diffuse radiosity. ! Graphics Lecture 13: Slide 17! Patching Problems " •  We need to divide our graphics scene into patches for computing the radiosity. ! •  For small polygons we can perhaps use the polygon map, but for large polygons we need to subdivide them. ! •  Since the emitted light will not be constant across a large polygon we will see the subdivisions ! Graphics Lecture 13: Slide 18! Large Polygons " •  Each patch will have a different but constant illumination.! •  Thus we will see the patch boundaries unless either: ! –  Patches project to (sub) pixel size or
 ! –  We smooth the results (eg by interpolation) ! Graphics Lecture 13: Slide 19! Form Factors" Form Factors •  The form factors couple every pair of patches, determining the proportion of radiated energy from one that strikes the The form factors couple every pair of patches, determining the other. ! proportion of radiated energy from one that strikes the other. 1 Fij = |Ai | Z Ai Z Aj cos cos ⇡r2 i j dAj dAi Graphics Lecture 13: Slide 20! . 16 / 29 Form Factors - the- definition Form Factors the definition " •  The cos terms compute the projection of each patch in The cos terms compute the projection of each patch in the the direction to the other. ! direction to the other. •  If the patches are in the same plane, facing the same Ifway, there areno the same plane, facing the same way, thereother the patches is in coupling. If they directly face each is they are If they directly face each no coupling.maximally coupled. ! other they are maximally ! coupled. 1 Fij = |Ai | Z Ai Z cos Aj cos ⇡r2 i j dAj dAi Graphics Lecture 13: Slide 21! . 17 / 29 Form Factors - simplifying the computation" Form Factors - simplifying the computa...
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This document was uploaded on 03/26/2014.

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