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Lecture 13 - Radiosity I

# 4 29 4 29 radiosity radiosity radiosity is dened

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Unformatted text preview: R incident Iref lected R I Iincident where RR isR is the (viewpoint dependent) reﬂectance where is the (viewpoint dependent) reﬂectance function. •  where the (viewpoint dependent) reﬂectance function. function. ! ! Graphics Lecture 13: Slide 8! . 4 / 29 . 4 / 29 Radiosity Radiosity" Radiosity is deﬁned as the energy per unit area leaving a surface. •  Radiosity is deﬁned as the energy per unit area leaving a It is surface. of the sum ! I the emitted energy •  It is the sum of! per unit area (if any) I thethe emittedenergy. per unit area (if any) ! –  reﬂected energy –  the reﬂected energy.! For  For a small of the of the surface (patch) dA the emitted • a small area area surface (patch) dA (where (where the energy can be regarded as be regarded have: emitted energy can constant) we as constant) we have:! BdA = E dA + R I Notice that that we treat light sources as distributed •  Notice we now now treat light sources as distributed ! Graphics Lecture 13: Slide 9! . 5 / 29 Divide the scene into patches i = 1, . . . , n Radiosity" For the ith patch, let: •  = total energy leaving I BiDivide the scene into patches i = 1, ..., n •  = the energy emitted I EiFortotali-th patch, let:! by patch itself –  Bi = total energy leaving the patch! Ri = reﬂectance value –  Ei = total energy emitted by patch itself! I Ii =  incident light energy arriving at the patch – Ri = reﬂectance value! –  Ii = incident light energy arriving at the patch! I   With this notation, the equation can be re-written With •this notation, the above above equation can be re-written! Bi = Ei + Ri Ii (1) . Graphics Lecture 13: Slide 10! 6 / 29 Collecting energy Collecting energy " We can estimate incident energy for patch i as: We can estimate the the incident energy for patch i as: ! Ii = n X Bj Fij j =1 where the sum is taken all surface patches of the of the Where the sum is taken overover all surface patches scene scene ! The Bj ’s’s in the sum repre...
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