about calculating the filter size, we need to first calculate the estimation:
imo, to calculate the penumbra size, we can do:

penumbraSize = (dReceiver - dBlocker) / dBlocker * lightSize

actually my questions are from your code:

float SearchWidth(float uvLightSize, float receiverDistance)
{
	return uvLightSize * (receiverDistance - NEAR) / eyePosition.z;
}

for the search area width, i don't know why you use eyePosition.z instead of the shadow space z here, what is the reason? is the eyePosition the main camera in the scene? could you please elaborate?) (http://developer.download.nvidia.com/whitepapers/2008/PCSS_DirectionalLight_Integration.pdf is not available now...)

also, what is the reason you use NEAR / shadowCoords.z here?

float penumbraWidth = (shadowCoords.z - blockerDistance) / blockerDistance;
float uvRadius = penumbraWidth * uvLightSize * NEAR / shadowCoords.z;

Thanks!

can you supply a obj file ?. I can't import the obj file exported from the newest blender. can you supply one obj?thx

error message: Run-Time Check Failure #2 - Stack around the variable 'Val' was corrupted.

call stack:

AntTweakBar64.dll!CTwVarAtom::ValueToString(std::string * _Str) 行 510 C++
AntTweakBar64.dll!CTwBar::ListValues(std::vector<std::string,std::allocatorstd::string> & _Values, std::vector<unsigned int,std::allocator> & _Colors, std::vector<unsigned int,std::allocator> & _BgColors, const CTexFont * _Font, int _WidthMax) 行 4109 C++
AntTweakBar64.dll!CTwBar::Update() 行 4575 C++
………………