Tuesday, November 20, 2007

Eliminating noise

The last couple of days I have tried to reduse the noise in the SSAO output. It proved to be a hard problem. My initial attempt was to simply apply a separable gaussian blur. It produced a nice, smooth image. But as I expected it resulted in ugly halos around object edges when combined with the albedo term. Next I tried to combine the gaussian with some edge detection trickery. Looked kind of cool, but unfortunally it just reduced the halos and did not eliminate them.

Then I turned to bilateral upsampling (see Jeremy Shopf's blog). Eliminated halos, but the SSAO input was way to noisy for simple bilinear filtering. My last atempt was a combination of a box blur and a variant of bilateral filtering. The result is acceptable. I'm not satisfied, but it will do for now.

Next up is some speed optimizations and then I'm on to indirect lighting.

SSAO + "bilateral filtering"-hack

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