// Compute tap contribution based on depth and blurriness

float fTapContribution = (fTapDepth > fCenterDepth) ? 1.0f : fTapBlur;

Is this to reduce the near blur?

]]>i’m implementing now sdsm technique from Andrew Lauritzen article with evsm filtering using opengl 4.5. So i read almost everything about esm, vsm, and other *sm, but cannot understand some points. I also looked through your shadow sample and intel’s also (i do not know direcx, really). So the questions:

1. When we used positive and negative exponent factors in evsm, why the first is 42 (this i understand), but the last is 5(this is completely obscured to me).

2. All the articles about shadow mapping say that you should use front face culling when rendering to the shadow map (this should decrease wrong selfshadowing and acne), but both you and andrew lauritzen use NoCull in your samples. Why?

3. In Andrew’s sample he “normalizes” exponent factors with cascade ranges, to make the transition between cascades less noticeable. You do not do that. I have ranges from several meters to 10s of kilometers (flight simulator). Is there any point to do that?

4. When blurring evsm, does it make sense to blur with decreasing kernel size (for example, 7x blur for cascade 0, 5x for 1, 3x for 2 and no blur for the last. Is there any “state of the art” technique?

5. The same question with light space orientation relative to camera space. I have only sun direction (z-axis), so i can rotate the light space basis around it (xy axes), is there the “right way” to do that? stick it to camera “up” vector or to world up vector?

6. Is there any point to do some shear transformation to light space. Could it help to better utilize sm resolution, I didn’t see any articles on. Now my lighspace is a box.

7. Everybody uses square shadow maps (1024×1024 for ex.). Is it possible to find better aspect knowing scene parameters.

Thank you for your answer :-):-) ]]>

I updated the link to Wang et al.’s paper. Thank you for pointing that out!

As for Stephen Hill’s fitted SG irradiance approximation, the link that I currently have in there just points to his home page, which is still the same. He hasn’t formally published his approximation anywhere, so I don’t have anything else to link to at the moment.

]]>1. Can you update the links to the wang paper, since john snyders web site is reworked

2. Can you point a link to the SGIrradianceFitted, since the selfshadow is also updated. ]]>