Chapter 5 Frequency Space Environment Map Rendering

In the previous chapter on irradiance environment maps, we have seen how frequencyspace analysis can be used to efficiently compute and represent convolutions of the incident illumination with the low-pass Lambertian reflection function, i.e. clamped cosine. An obvious question is whether a similar approach is possible for general BRDFs. In this chapter, we will present such a method. We will therefore have shown that the signal-processing ideas can be used to significantly increase the quality of interactive rendering. Since we are using frequency space methods to render with environment maps, we have entitled this chapter Frequency Space Environment Map Rendering. The next chapter of the dissertation will switch from forward to inverse rendering, extending and applying the theoretical framework to determining lighting and BRDFs from sequences of real photographs.