Texture Banding

[treddie]

I am curious if anyone has seen this problem before. I was experimenting with a fabric texture, composed of a bump map for the weave, and a holes mask for the spaces between the fibers. I built a material mix with a basically white fabric with the bump texture, and the mask for popping the holes in the texture.

What happened is that I get banding in the texture which is not in the bump or mask images. The samples of the maps in the attached image are just small crops of the entire images. These maps are perfectly tiled with no mismatching anywhere because they were based on a perfectly repeatable starting tile.

At first I thought I had a moire problem, so I thought maybe it had to do with the render's pixel size and the size of the holes in the mask. So I changed the render resolution to something entirely different but the amount of banding did not change.

And if I increase the bump strength, the banding gets more pronounced.

[face_off]

It's a long shot, but try increasing rayepsilon.

[kavorka]

did you check your UVs?

try applying a checker material to see if that's the problem. If you have a modifier sub dividing your mesh before export (don't know what program you are using, but I think it's mesh smooth in 3Ds Max) it can sometimes warp the UVs. I try to sub divide it once before unwraping to make sure the UVs don't get skewed, then add a sub division modifier so it divides it more on export.

[treddie]

It's a long shot, but try increasing rayepsilon.

No go. Would have been a nice simple solution though!

did you check your UVs?

I had checked the normals prior to my IP, and they were at least pointing in the right directions. But it is interesting that you also mention SubD, which I definitely had to do to get the fabric wrinkles (since Octane does not (yet) support Displacement). I applied the displacement map in Blender along with a 2x SubD to get the final "Super" mesh. I hate doing it that way because the poly counts are way too high for even ME (a high poly guy!). I only use Blender for converting Displacement maps to mesh. My scene building app is C4D, but their displacement-to-mesh conversion really sucks.

Now, in Blender, my first modifier in the stack is the Dispalcement, followed by the subD. I wonder if I reversed that if it would fix it.

[kavorka]

I'm a Blender user too.
What's more important than normals is the UVs. I like to apply a check material to the mesh to make sure they are all *mostly* square and adjusting the UVs accordingly.

As for the stack, you want the SubD to be applied first before the displacement so that it has more polys to work with.

[treddie]

I'll give that a try, and report back.

[treddie]

It looks like the SubD thing is the problem as you suggest, but I don't exactly know why. Some programs can open the mesh and it is perfectly smooth, whereas Octane gets the artifacts as seen in the attached image. And the artifacts are restricted to just the wrinkles in the fabric, not overall as the banding indicates.

[abstrax]

Try opening the exported OBJ file in Blender and apply the texture there. Do you get the same banding there, too?

[treddie]

That may take a while...The only reason I came to Blender was to get displacement converted to mesh, and Blender's GUI is so backward and moronic, I'll have to figure out how to do it. Not having much luck when the online tuts refer to old versions and the interface is all different and all. And they refer to buttons that don't exist.

[abstrax]

That may take a while...The only reason I came to Blender was to get displacement converted to mesh, and Blender's GUI is so backward and moronic, I'll have to figure out how to do it. Not having much luck when the online tuts refer to old versions and the interface is all different and all. And they refer to buttons that don't exist.

You can "bake" displacements using the displacer object. Don't know how good or bad it is, but it's a way.