No texture-mapping is required for the irradiance with our approach. The main ingredient is the derivation of an analytic formula for the irradiance in terms of spherical harmonic coefficients of the lighting. For rendering, the key observation is that the Lambertian BRDF behaves sufficiently closely to a low-pass filter that we need consider only the first 2 orders of spherical harmonics, i.e. 9 parameters. The simple form of the first 9 spherical harmonics makes implementation straightforward. The images on the right illustrate some of our results.
More information is found in the paper.
Clicking on each of these figures will bring up a high-resolution version. The diffuse shading on all objects in computed procedurally using our method. This is one frame from an interactive session using the Stanford Real-Time Programmable Shading system, in which our rendering algorithm can trivially be implemented. Another scene used to compare interactively images obtained from our method to those obtained by computing irradiance environment maps in the traditional way. It can be seen that there is no perceptible difference.