bumpmap, shadow edge, sharp transition

[Frieder]

Hello all,
the scene is only an extrudet ellipse with a bumpmap and lit with sun. The result you can see here. I never struggled over this issue. Is there any solution to avoid this sharp transition between direct light an indirect lighting.
Thank you and best Regards

[vlado]

It might help to increase the shadow bias for the light a bit.

Best regards,
Vlado

[Dariusz Makowski (Dadal)]

You sure its not where ur UVW tile ? Or geometry issue?

[Frieder]

To increase the shadow bias won´t help. And I think that it´s not an UV or geometry issue. The edge change exactly with the position of the sun.
Here is the file
http://www.workupload.com/file/xTFaTXw

Thanks

[3DMK]

I often get the same problem on tree trunks......any idea anyone???

[vlado]

Well, it's caused by the fact that bump mapping is a cheat; when it's too strong and the normals deviate too much from the original surface normals, you start getting these issues. Displacement works better usually, but of course it's much more expensive. There is a possibility to adjust the shadow point based on the bump map "height" which makes the issue less apparent, but this is not enabled currently in the VRayMtl material (it doesn't always work as expected as many of the 3ds Max procedural maps return inconsistent results for their color and the bump outputs).

Best regards,
Vlado

[Dariusz Makowski (Dadal)]

Would a normal map approach work in this case by any chance?

[3DMK]

Would a normal map approach work in this case by any chance?

I only use NORMAL maps on the tree trunks & get that issue so I it seems Normal maps suffer the same problem.

[windowlicker]

Increasing the shadow bias does help. I made a sample scene just now, and to get the render I want, I will increase the bias when I increase the bump amplitude. You will still have a pretty sharp "edge" but it will get softer as the bias increases. Having a bias higher than a few millimeters will have a negative effect on the way the rest of the scene renders. Small details might be lost. It's a trade-off I guess.
You could also argue that this is the way bumpy (rough) objects are affected by light. You can compare it to the Oren Nayar reflectance model... sort of. A bit to pronounced maybe.

If you only have a limited area of your image with this problem, I'd go for some 2d displacement though. Just for those objects.
I often go for displacement whenever I have bumpy surfaces, especially close to camera. It just looks so much better, and it usually doesn't take that much longer.

[samuel_bubat]

Probabely not, because a normal and bump map basically do exactly the same. Faking normals.

[JeffG2]

ping for reference

[Frieder]

Increasing the shadow bias does help.
....
If you only have a limited area of your image with this problem, I'd go for some 2d displacement though. Just for those objects.
I often go for displacement whenever I have bumpy surfaces, especially close to camera. It just looks so much better, and it usually doesn't take that much longer.

Unfortunately in my case it definitely won´t help to increase the shadow bias. For this case now I changed to the displacement modifier (2D). And like windowlicker said, it cost not that much more rendertime and the results are pretty good now.
Thanks at all