| OCR Text |
Show 142 point light source in any given direction. The net Q (Fv(Pu.Pv)-Fu(Pv.Pv)) S R (Fu(Pu.Pv)-Fv(Pu.Pu)) S Norm' = Norm + Q Pu + R Pv If this is a bit much to calculate at each picture element one could scale the F function samples by S as a pre-pass for a particular patch. Lighting Models We now discuss the second aspect of intensity calculations, that of modelling the amount of light striking the surface from various directions. We have given a function which computes the intensity comtribution for a reflected intensity due to a distributed light source will be the sum of the contributions of light reflections due to light from all directions. This takes the form of a surface integral 1T/2 21T J J I ( e , q, ) R ( e , q, ) sin q, de d q, o 0 where 1(8,.) is the light intensity coming from the polar direction e and; R(e,) is the amount of light reflected to the eye for light coming from the direction e,'. is the function we have derived in the previous section, |
