VRay GPU Next and very jaggy shadows with VRay Sun

[D3Pixel]

Hi

I have an issue with VRay GPU Next and VRay Sun Shadows, no matter what settings I try, I can not get rid of those jaggy shadows. It has to be something simple??

I have tried re-creating the sun, checking that VRay Materials exist on the objects, changed every parameter in VRay GPU Setting while watching the IPR and still can not find out what causes this.

Any ideas?
Thanks

[tashko.zashev]

Hi,

Can I see the scene for this issue?

[D3Pixel]

Attached is a simple scene that shows the problem when a shadow is caused from a lip of another object. This is VRay GPU Next. Does the same in VRay Next. Does not do this in Arnold.

Thanks

[D3Pixel]

This is what the above scene zip renders on my machine.

[tashko.zashev]

This is actually expected behavior and we are not considering it as a bug. The two cylinders require a bit more segments/tessellation to produce nice and smooth shadows. That would be the correct way to fix this jagged shadow border especially when using sun or direct light sources. There is an old discussion about the same thing somewhere in the forum, will try to find it.

[D3Pixel]

I do not understand. Even adding 100 sides, 50 height segments and 5 caps segments to both cylinders, the shadow is identical. It does not change it at all.

[D3Pixel]

Ah, I had to add 200 sides before it went smooth. This will blow my scene polycount which is already at around 6 million into the 10's of millions. I will have to push Turbosmooth into the 4-6 range for every object.

[urbanite]

Smooth modifier did not help?

[D3Pixel]

No, it seems many render engines can not do this kind of shadow. Surprised nobody has tried to solve it as it certainly is not correct or expected.

[Morbid Angel]

Ah, I had to add 200 sides before it went smooth. This will blow my scene polycount which is already at around 6 million into the 10's of millions. I will have to push Turbosmooth into the 4-6 range for every object.

You really don't need that many subdivs. I would use vray subdivision and not turbosmooth. The fact that the object appears smooth in renderer with low segments is a not physically accurate phenomenon and as such will have limitations. You are trying to raytrace a shadow which is sampled from actual polygon onto geometry and normal viewport smoothing is not going to fix that issue unfortunately. I've checked with vray and arnold and both exhibit the same issue.