I implemented a bilateral gaussian blur with single dynamic weights, respecting the depths and surface normals of each sample pixel compared with the base pixel. I still have to fix surface incontinoutities in the sampling process, but it looks already better!

The images are the AO result after bilinear downsampling, AO approximation, blur and bilinear upsampling. Remember, I calculate on the half of the resolution..

Old (with 4x4 box blur):


New (with bilateral gaussian blur):


Next thing after fixing the above mentioned stuff is bilateral upsampling and switching to A8 exclusive features to reduce the overall texture lookup-count.