Try to replace
Code:weight *= max(0.0, 1.0 - (2000.0 * EDGE_SHARPNESS) * abs(tapKey - key));
by
Code:weight *= max(0.0, 1.0 - ([B]400.0 [/B]* EDGE_SHARPNESS) * abs(tapKey - key));
I've seen what you describe happen and it bothered me a bit but I seem to no longer get it now with the latest changes I submitted. I just took a shot in AC1 and unless my eyesight is getting bad (I'm getting old after all !) I'm not getting a grid pattern at all :
SAO
HBAO (that's not really the point but I can't help comparing)
Your shots look good. I looked closely and I can't see that grid either but I still can't shake it off.
http://i4.minus.com/iyHHiwrJAtSDm.png (AO off)
http://i1.minus.com/i1g22zQ1ly074.png (AO turned on, look at his hand)
http://i7.minus.com/ijiJZmizAWAQJ.png (AO map)
Some of the settings I use are 8 samples, edge sharpness 0.1, scale 2 and 200.0 * EDGE_SHARPNESS (also tried 400).
The recent sao.fx you posted is...not really working for me. AO map is showing pink and white with some chaotic black lines. I'm still using the gedosato.dll you posted a few days ago.