Maniphest T54498

Harsh shadows when using Normal, and Bump maps
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Assigned To
Brecht Van Lommel (brecht)
Authored By
Bret Church (mbcburt)
Apr 2 2018, 9:38 PM
Tags
  • BF Blender
Subscribers
Brecht Van Lommel (brecht)
Bret Church (mbcburt)

Description

System Information
Windows 10 and NVIDIA GeForce GTX 1080

Blender Version
Broken: (2.79b)
Worked: (optional)

Error with the fall off of bump and normal maps using cycles. Getting harsh shadows from lights on objects with normal or bump mapping. On some objects the fall off works on one side of the mesh but is harsh on the other side, even with sub divided surface modifier increasing subdivisions. In the node editor I do have the image texture set to non color data.

Exact steps for others to reproduce the error
I exported out an .ABC alembic file from 3ds max. I imported the .ABC file at a .01 scale. applied the principled shader with a image normal map, also tested bump map but I get the same eror. I also used an HDRI images for the lighting, although I removed the HDRI and tested with a normal light and got the same issue.

character.blend7 MBDownload

Related Objects

Event Timeline

Bret Church (mbcburt) created this task.Apr 2 2018, 9:38 PM
Bret Church (mbcburt) added a comment.Apr 3 2018, 2:11 AM

I see this is a normals issue now, the alembic files do not bring normal in the export so i just assigned the standard smooth. I am not sure exactly how to fix the normals to work with my normal maps created in zbrush.

Brecht Van Lommel (brecht) lowered the priority of this task from 90 to 30.Apr 3 2018, 4:00 AM
Brecht Van Lommel (brecht) added a subscriber: Brecht Van Lommel (brecht).

In general such artifacts can happen if the normals are too different from the actual geometry, and the low poly geometry reveals itself. It's best not to set Strength so high, usually 1.0 is what you need to get the same result as the original mesh in ZBrush.

In this case I'm guessing the normal map is perhaps an Object Space normal map, or a Tangent Space normal map baked with a different convention. So I suggest to try different space on the Normal Map node in Blender, or bake in ZBrush with different settings.

If you still think there is a bug, please attach a simplified .blend with the normal map image attached as well, since the current one is incomplete so we can't test it.

Bret Church (mbcburt) added a comment.EditedApr 3 2018, 7:58 AM

Thanks Brecht, I thought it may be an issue with the alembic export/import. Now it looks like a bug. I tested an exported .obj of the model and one as alembic. they both looks about the same. The issue is on both models, the normal map was generated in zbrush, and then over to Quixel.

It looks like the .obj is not correct as well. There is an issue here, a bug. I attached the file with the pants as an .obj and the alembic import to compare. I will attach the normal map as well. The left side of the model has an incorrect fall off when compared to the right side. This is mostly noticeable when size of the lamp in the scene is turned down so the shadows don't have so much fall off. The lamp size in this scene is turned down to 0.018. Just hook up and unhook the normal map to see the nice fall off on the model without the normal map and then the left side getting that harsh line when the normal is connected.

Normals Bug.blend6 MBDownload

Bret Church (mbcburt) added a comment.Apr 3 2018, 5:47 PM

Sorry, more testing shows this is not a bug, this issue is also showing up in 3ds max. I will be trying troubleshoot this on my end.
Thanks

Brecht Van Lommel (brecht) changed the task status from Unknown Status to Unknown Status.EditedApr 3 2018, 5:52 PM
Brecht Van Lommel (brecht) claimed this task.

It's another case of the terminator problem. We have some work towards improving it in D2574 but there's no easy solutions in general.

If you can use a displacement map instead of a normal map it helps since then the geometry will match the normals.

Bret Church (mbcburt) added a comment.Apr 4 2018, 6:16 PM

Got a fix for this issue. I added a vector curve node in with a mix rgb and now it has a nice fall off. Good to go. I'll add a screen shot of the nodes tree with the fix.

Philipp Oeser (lichtwerk) mentioned this in T54671: Poor shadow smooth when using bump.Apr 17 2018, 1:02 PM