View Full Version : Normal map (from zBrush) artifacts

12-07-2011, 01:09 AM
I'm getting these weird artifacts when using normal maps in LW9.6 (from zBrush) I have applied the normal map in node editor.

I know the geometry isn't that great and the pole on the back of the beetle probably contributes to the issue, but I find it weird that without normal map there's no issue and model renders fine. (see the screenshot) What's originally 5 point pole in original mesh shouldn't be that much of an issue.

I created the model in zBrush and exported it has obj in subdivision level 1.

If you have any ideas how to fix the issue, please let me know.

12-07-2011, 01:13 AM
here's the normal map from zBrush

12-07-2011, 02:01 AM
check if your UV's are welded in that area.

12-07-2011, 02:33 AM
Attach object so we can play with it.

12-07-2011, 02:37 AM
I see that you have used sub-patches, right? And you froze it in Modeler, then imported to Z-Brush, or you send sub-patched object without freezing?

12-07-2011, 03:27 AM
The base mesh was created in Lightwave and then sent to zbrush for sculpting and uv mapping. The original quad mesh was then brought back without freezing as quads, and then subdivided again in LW.
How can I check whether UVs are welded in that area? There are no seams in that spot for sure.

12-07-2011, 03:31 AM
Yes, I sent it to zB without freezing.

12-07-2011, 03:36 AM
Sub-divided LATER? You can't do that. Normal map is relative to the mesh that you used in application while creating it..

12-07-2011, 03:38 AM
Load your normal map on exactly the same object which was used in Z-Brush, and render, to see whether you have artifacts.

12-07-2011, 03:39 AM
Converting normal map from one mesh to another must be done the same way as when baking from high res to low res objects in game production.

12-07-2011, 05:00 AM
Sub-divided LATER? You can't do that. Normal map is relative to the mesh that you used in application while creating it..

This got to be it. Testing tonight.

12-07-2011, 05:41 AM
This is what I did:

I went to zBrush and deleted the subdiv level 1. Then I re-created Normal map in (what used to be) subdiv level 2, and exported the model and textures.

I was able to eliminate the issues on the back, but similar artifact now exists on the face. (see the image)

I tried with Tangent, Adaptive, SmoothUV and SNormals turned on in zBrush while creating normal map, and with all of them off. I'm still getting same issue.

By the way, should I use Tangent or not?

12-07-2011, 05:54 AM
Ah! I realized now the issue. I was creating normal map in the lowest subdiv level in zBrush while I should use second highest.. working perfectly now!

12-07-2011, 04:05 PM
Try flipping r , g channels (form rgb), in normal map node