ZBrushCentral

Displacement Map Artifacts

ZBrush Usage Questions
#1

This is something that’s been bothering me, and I really need to fix. So the render engine I’m using can’t handle tangent normal maps (Blender Cycles, a progressive engine), and I’m stuck using black/white displacement maps for my sculpted details. I can only bake these in Zbrush (if any free program can bake displacement maps let me know). They look fine from looking at the map image itself (not lossy looking), but whenever I apply it to the mesh I get this really strange stair-stepping artifact, due to some kind of compression or something.

Now I’ve tried different image formats, exporting from Zbrush. The way I do it is, make displacement map > clone disp > make texture map > export (if I’m doing that part wrong, tell me) And if this is just a problem with blender then please tell me (if any of you have Maya/Max please test the dispMap)

I suppose it’s not too much of a problem, as long as I render from a certain distance, but normal maps don’t have this weirdness at all. Please help if you can :confused:

Thanks

oh and here’s a sample of what the texture itself looks like:

http://img525.imageshack.us/img525/1874/undersuitdis.jpg

#2

If you are exporting displacement maps from the Texture palette then you are compressing them within ZBrush (reducing 16 bit to 8 bit per channel). This is almost certainly causing the stair-stepping that you see. You need to export directly from the Alpha palette after cloning the map.

HTH,

#3

Ok, I tried exporting from the Alpha palette, and it exports in 16 bit, which has less stair-stepping, but is still noticeable. I’d like to be able to export in 32 bit float… I see there’s a “32 bit” setting under the displacement map sub-palette, but it only applies whenever you hit “Create and Export Map.” I’ve tried using that but it just makes a flat gray .tif image. Any way to export 32 bit maps, not using the “Create and Export Map” button?

#4

If you are still getting stair-stepping with 16 bit then it may be that you need to look at your settings when you render in Blender. For example, there may not be enough subdivision at render time to support the map detail.

The only way to export a 32 bit displacement map from ZBrush is to use the Create and Export Map button. However, do not assume that because you cannot see any detail on the map that there is none there. It is unlikely that you will see the detail by simply opening the map in Photoshop. The range of values in a 32 bit map is huge (beyond the gamut of ordinary monitors) and the degree of variation in the average displacement map genrally too small to see.

#5

Hi, i think i can help you. I spend the whole day trying to fix this weird “wave” artifacts. Is impossible…with zbrush 4R2. It Doesnt matter that i changed my Uvs for the Uv Master´s automatics Uvs, select other image format, other preferences or more or less subdivisions, or GoZ to 3ds max to AutoSmooth normals, or delete polygroups…nothing.
At least for me this is what it works in my imac 21.5 bootcamp Windows 7 x64:

-Open your subtool in zbrush 4R2. Export your high subdivision level and your low subdivision level. I choose subdv 5 and subdv 2, because my mesh is organic, a realistic head, and its easy loose detail at the ears.
-Open Zbrush 4, the old one. Import your models (i mean IMPORT, not Load Tool), low and high resolution, it doesnt matter what is first, only thing important is that you load another subtool (a cilinder, …) between your models, to me works this way.
-Once you got your high and low res models as subtools, select the high one, pick up Tool>Subtool>Append and choose the other one, the low res model.
-Select the Low Res model and Pick up Tool>Geometry>Divide as you need to get closer to the detail of your high res model, 4 subdivisions is what i need

(i load a 2subd as Low Res model, so to get close to a 5Subd High Res model i need 3 subdivisions more…so my Low Res model have 4 Subd now).

-Keep sure that you have selected your Low Res model with enough subdivisions and that you have loaded in the same subtool your High Res model at the top of the list (and Keep sure that you have selected your Low Res model with enough subdivisions again) and go to Tool>Geometry>Project all.
-You will see that the projection detail is perfect. Now uncheck the eye of your High Res model or delete it.
-Get the Zplugin Uv Master.
-What i did is next: i check Polygroups and uncheck Symmetry in the Uv Master Dialog (Zplugin>UV Master), because with polygroups you can select part of your mesh like Uv Seems, and uncheck symmetry because my model is a asymmetrical head. Pick up Unwrap.
-Tool>Uv Map>Uv Map Size to chooes the resolution of your map. Tool>Texture>New Texture. Clone Texture (in texture Dialog). Menu-> Texture>MakeAlpha. Menu-> Alpha and check the Texture.
-Choose your “Low Res model” (now remember that you have all the subdivision levels and detail that you need) and Tool>Displacement map> load the texture of the previous step and check Adaptative, Smooth Uv, Flip V, 3 Channels, Mode active and DpSubPix 2. Create DispMap and wait a few seconds or minutes and thats is.
I hope this would be helpful to you too.

Note: I tried get the displacement map with zbrush 4R2 and Mudbox 2012 and the results are the same: nothing useful, weir artefacts. Perhaps my mesh has something weird, but with zbrush 4 it doesnt matter. The only problem that i can see now is the automatic Uv thing, need to check out with time.