GPU Pro 5

1. Physically Based Area Lights 77

p˝ = p

r

n

dA

p

p

p

Figure 1.7. Geometric construction of point p

r

when the light plane is pointing away

from the surface.

As previously discussed, we were searching for the most important sample of

the integral on a segment between points p

r

and p

c

representing component-wise

local maximums (see Figure 1.8).

With those conditions set, we used a computational software package to nu-

merically find a point on line

p

c

p

r

that approximates the most important point

as much as possible. We worked on a data set of several hundred area lights ran-

domly generated as disk or rectangle light shapes. For every light shape we found

a point