- User Since
- Apr 15 2019, 11:53 AM (26 w, 3 d)
I'm not really sure but I think it might be related to the linear interpolation of the vertex normals on the face, that does not match the true normals a circle would have (correct me if I'm wrong). So each face get a set of interpolated normals that is slightly wrong, and since the interpolated normal is used to build the shading normal with the tangent normal map, correlation artifacts appear.
Try the following: build a cylinder in blender, remove the top and bottom faces, then in edit mode select all faces and subdivide them multiple time. Put your cylinder in smooth shading and you will see the the individual original low res faces appear, even with opengl rendering.
I guess this is because the new vertices created with subdivision have a normal computed from linear interpolation, but I'm not familiar with subdivision algorithms in general and the one used by blender in edit mode so I can only guess. Try to display the normals on edit mode with the overlay, you will see that the normals of the newly created vertices do not create a perfect circular pattern.
Yeah the problem of shadow terminator for normal maps seems to be fixed thanks to https://developer.blender.org/D5399
- Before the fix with the scene provided by Stefan: https://cloud.blender.org/p/home/5da861858ca20a9414af8cca?t
- After the fix: https://cloud.blender.org/p/home/5da861fad2bf7c8344de5a5b?t
Fri, Oct 11
Thu, Oct 10
Wed, Oct 2
To address this issue, what do you think about adding a "shadow bias" parameter to control an offset from the surface along the geometric normal ? I know its not a perfect solution but at least it would allow users to avoid a lot of rendering artifacts that are due to shadow termination.
Wed, Sep 25
Sep 4 2019
May 13 2019
Hi, It seems the issue is solved in the build "version: 2.80 (sub 61), branch: blender2.7, commit date: 2019-05-12 22:25, hash: rB05f1451d7248", thank you for looking at this :)