ZBrushCentral

Displacement Artifacts --> Maya --> V-Ray

ZBrush Usage Questions
#1

Hey Guys!

I think this is my first post. So, hello to all you cool sculpt guys and girls. ^^

I go a problem with the displacement in V-Ray. I always get rendering Artifacts at points like the ones marked in the attachment. I always get seams at these places. (like you can see in the second image) The map is 4k *.exr.
I guess I’m doing something wrong but I don’t know where to look for anymore.

Maybe one of you found a solution for that.
Or is the Topology simply crap and I need to avoid these 5 edge Stars.

thanks in advance
greetz
Ben

Rendered image

topo

vray settings

zbrush settings

Attachments

artifact.jpg

artifact_vray.jpg

artifact_zBrush.jpg

artifact_render.jpg

#2

I don’t think the 5-point areas are an issue- but I know ZB doesn’t like 3-edge engons. Your Disp map settings appear correct but check your UV map for any overlapping vertices. Try a 16 bit Disp Map and see if it’s any better. Have you upgraded to the latest 4R6?

#3

http://docs.pixologic.com/user-guide/zbrush-plugins/multi-map-exporter/

Try the multi-map exporter instead of the displacement map section of the tool palette. The issue maybe the amount of “bleed” in your texture, filtering on the texture map or the nearness of your UV shells. The setting you need to adjust for the “bleed” or “overpaint” is the Map Border setting of the plugin. Depending on your resolution you may need something large, 2K texture try 16px for a test. Obviously your UV shells will need this much space between them as well.

#4

Hey Guys,

thanks for the ideas.

@Ted
I checked the GEO. There are no overlapping Polygons. You suggested trying 16 bit. I’ve done that. Sadly, same artifacts.

@nimaineb
I didn’t like the Multimap Exporter until now, but I’ll definetly try what you suggested. Maybe I’m starting to like it. Normaly MME was not an Option because I use EXR and it only exports TIF. But as I said. I’ll try.

#5

Sorry, the only other thing I can think of is to increase the DP Sub Pix from 0 to 4 and increase the Mid from 0 to .5- supposedly that helps Disp Map accuracy. I render in MR, and there are Approximation Editor settings that can be tweaked, but I don’t know about VRay. Maybe try moving that 5 point area to another spot not as noticeable. Scott Spencer recommends using the Smooth UV under Tools/Displacement to remedy small spikes on UV seams. Maybe try cleaning up that spot on the Disp Map itself? There always seems to be some problem in making Disp Maps- I retouch as needed on the final render when all else fails

#6

Ok, guys guess I got the Problem, but no really cool solution. It definetly got something to do with uv Edges that run diagonal over the Displacement Map. Under Tools->UV-Map zBrush offers some automatic UV Layout Methods.
I tried around and got the best results with AUV. No Seams visible.

The Workflow that is working for me is:


  • modeling Base Mesh in Maya
  • Layout UVs in Maya
  • Sculpt in zBrush
  • when finished, export final model Base Mesh
  • duplicate final model
  • on duplicate use AUV and export Displacement Map and Base Mesh (<-- Displacement Mesh)
  • In Maya I use Transfer Attributes to copy the Texturing UVs onto a second uv Set on the Displacement Mesh.

It’s not elegant, but working ok.
What do you think?

greetz
Ben

#7

Ok, guys guess I got the Problem, but no really cool solution. It definetly got something to do with uv Edges that run diagonal over the Displacement Map. Under Tools->UV-Map zBrush offers some automatic UV Layout Methods.
I tried around and got the best results with AUV. No Seams visible.

The Workflow that is working for me is:


  • modeling Base Mesh in Maya
  • Layout UVs in Maya
  • Sculpt in zBrush
  • when finished, export final model Base Mesh
  • duplicate final model
  • on duplicate use AUV and export Displacement Map and Base Mesh (<-- Displacement Mesh)
  • In Maya I use Transfer Attributes to copy the Texturing UVs onto a second uv Set on the Displacement Mesh.

It’s not elegant, but working ok.
What do you think?

Or is there a better way? (I hope there is…^^)

Second Idea would be exporting to Mudbox and export a Ptex Vector Displacement map.

greetz
Ben

#8

Looks like you’ve figured it out- For my Maya mesh, I’ve been using UV Layout Headus, importing the UV mpped obj into ZB, sculpt it, and then use GoZ to bring it all back into Maya w/ the Disp and Normal maps. The trouble is that after drastically changing the shape of the original mesh, the UV layout dosen’t correspond, so I guess I’ll have to re-map it in ZB using AUV?
Have you thought of using GoZ? Please elaborate on your last 2 steps- are you copying the original UV map onto your newly sculpted mesh?