Here's another technique to produce fast soft speculars from an environment map.

The environment map represents samples of the environment as a 2D spatial field. Convert this field to the frequency domain, using Fourier analysis or Laplace transforms or wavelets or any of a dozen other representations.

These frequency domain representations have interesting properties. First of all, you can reproduce the value at any point damn fast, not as fast as lookup it up directly in the spatial map, but fast enough. Second, the frequency domain representation allows you to selectively discard certain frequencies and re-compute any single point as if the high frequency components were removed - essentially a kind of blurring.

So - with this technique, it would be possible to dynamically generate different convolutions wihtout actually convolving the entire map. Only the points that are needed would be re-built in a blurred version, because you build them on the fly.

 

---

Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)