bake displacement help needed

[volker]

I bake displacement maps only very rarely, so I have almost no experience in that regard.

I have modeled several patches (sewn onto clothing) in ZBrush, and added seams to them using separate geometry. Now, I would like to bake a displacement map onto the lowres version of the patches (that don't have the seams as separate geometry, I would like to bake the seams into the displacement map).

It kind of works, but the displacement map that Designer creates looks strange to me. It has a grid-like pattern to it that doesn't look correct to me.

What could cause this? How do I eliminate this grid pattern?

[Cyrille Damez]

Although not intuitive, it looks in fact like the correct result. Please see the explanations in this thread : https://forum.substance3d.com/index.php/topic,21696

[volker]

I read that it only works with the correct amount of displacement. How do I find that correct amount though?

Also, when exporting displacement maps from ZBrush, they do not have this grid pattern to them. Why is that?

In this case I can't use ZBrush unfortunately, as it is not possible to bake maps from one object to other.

[Cyrille Damez]

How do I find that correct amount though?

Eyeballing it by moving the displacement scale slider in Designer's 3d view should get you there. If for some reason you need the best precision possible, as far as I remember you can also switch off the auto scaling of the height map in the baker parameters and specify the scale/displacement amount you want, or disable scaling and bake to a floating point texture.

Also, when exporting displacement maps from ZBrush, they do not have this grid pattern to them. Why is that?

I don't know how Zbrush computes height maps, but I suspect that's because :

it is not possible to bake maps from one object to other.

As explained in the thread I linked to previously, if what is expected from an height map is to contain the distance from a low poly mesh to a high poly mesh, then it will necessarily have that "grid" look. I can only speculate that what Zbrush computes is of a different nature, possibly the distance between a subdivided simplified version of the mesh and the full detail mesh itself.