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[Solved] Issue with Normalmap


Ruud
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Hey guys,

I've got a little situation with the Normalmap on my Bonzai model. When i uploaded it to sketchfab i thought it looked fine but before all the materials are loaded i can see something strange and when i inspect the materials my normalmaps looks way off (ugly seams instead of wrapped neatly arround the surfaces) but my final model actually looks good. I just checked the normal map in 3d-coat when i set the normalmap's blending mode to "Standard Blend" and it looks exactly as it does on sketchfab (see image). I also noticed that in the sketchfab editor that my normalmap is set to "Flip green (-Y)".

After browsing the forum I've read that my export preset has influence about the flipping part but each preset (including a custom one) gives me the same result. I actually feel like something went wrong during the bake process...

Any thoughts?

Thanks!

Grtz Ruud 

bonzai-normal-map.JPG

normalmap-issue.JPG

Edited by Ruud
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Did you create the model in 3DC or import the model plus import the normal map?

Can you share the 3DC file if possible or the model file with the normal map plus the color textures.

PM me with a link if you want to share the file privately.

Edited by digman
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Carlosan: I was using version 4.8.07 and just upgraded tot 4.8.10 but i still got the same situation. Also redid the baking but got the same results (see images for my baking steps).

Digman: Everything was created in 3DC. I've tryed to PM you but i got a message saying that u can't recieve messages. This is the file:  https://drive.google.com/open?id=1TWAX6ayEYInC0MwHPh8vdGLcMUCnTk4o

Thanks for your help guys.

 

bonzai-baking-process_0000_Layer 5.jpg

bonzai-baking-process_0001_Layer 4.jpg

bonzai-baking-process_0002_Layer 3.jpg

bonzai-baking-process_0003_Layer 2.jpg

bonzai-baking-process_0004_Layer 1.jpg

Edited by Ruud
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Little update:

We just played around with a new bake that is showing the same "issues" near the seams. The green chanel looks to be causing the strange layout of the normalmap. We disabled the green channel in photoshop and manually moved the seams and then they fit so something is happening (during the bake of the green chanel?) that is causing this.

Is there an option that gives u control about the baking/flipping of the normals?

Edited by Ruud
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I am having the same issues with your model. 

My testing so far is changing the settings in preferences. No luck so far.  I do not believe that SketchFab supports MikkTSpace but that could have changed by now. Those are the settings I was chaning andI testing.

If you are using the 3DC upload feature inside of 3DC, I do not know if it uses your settings or not.

I will later try one of my models and see if the problem is there. I am curious about this problem though the rest of my day is tied up.

You can send your file to support at 3DC and and ask them test the file or inform you of any settings that need to be changed.

 

change.PNG

Edited by digman
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Success... Your model but for testing I used just these generic colors and triangulated the mesh. Only testing the normal map here. I re-baked to get a triangulated  mesh.

1. First you have a lot of non_planar polygons. Sketchfab by default does not triangulate the model to remove the non_planar polygons. When you bake to the paint room, choose to triangulate your model in the baking panel. Non_planar polygons will always cause artifacts.  A triangulated mesh is free of non_planar polygons.

2. Choose these settings shown in the picture of the preferences panel.

3. I did not test uploading from 3DC but uploaded manually. Should work for 3DC to Sketchfab exporter.

In SketchFab make sure your normal map is set to linear not Srgb. 

Flip the green channel.

Use lights not just the HDRI. It looks better in a number of cases.

Since it is a very low polygon model, I would adjust the Shadow bias up to about .4. The shadowing in Sketchfab could do with some improvements, esp on low polygons models.

The normals are correctly showing now, The shadow bias helps but is so so on helping the shadows in some areas. 

I would manually create seams as the auto map tries to make all the uv-islands planar but this can cause artifacts if there are placed at weird angles.

Also in the sculpt room do as Carlosan said about removing the non-uniform problem and you need to bake using name correspondence for baking to remove any occulsion errors where the separate retopo meshes intersect. Calosan mention this as well. These two items he mentioned are a must, not a choice for correct sculpting without errors and correct baking without errors. 

I have deleted the testing model from my sketchfab account. I will send you a pm with the generic model with the proper setup for manual uploading to sketchfab.

working.PNG

settings.PNG

Edited by digman
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Thank you guys for taking the time do dive into this problem and tips, really appreciate it!! I didn't know about the non-uniform scale, non-planar polys and normalmap preferences. 

The only thing that i don't understand is why the normal map itself looks so strange. I expect a smooth wrap around the object like the diffuse but instead u can see it with all the seams of the unwrap (in 3dcoat/paint room setting the normalmap layer to standard blend or in sketchfab check the normalmap with the material inspector). 

Yesterday i started working on a new sculpt (japanese torii gate) for the same project, did a manual unwrap and just applied all the correct settings but still get the same weird thing (see image).

Check this random sketchfab model for example and view the normalmap with the Modelinspector. It's smooth and u can't see any seams from the UV. https://sketchfab.com/models/8bc18542a5e04dcf8aadea834726a4af

How is this with your models?

Grtz,

Ruud

toriigate.jpg

Edited by Ruud
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Hey Carlosan, I've just made it bigger but that doesn't solve the issue. I was browsing the web for related situations and i hear a lot of talk about the tangent-space..

Also i found this image which i think shows the problem. The middle cube 3 is how i see all the normalmaps and mine looks like cube 4/5.

YgC0V.png

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Bigger and... do you changed Bake scan settings before bake it ?

 

Please try this: open on paint room any default mesh (Shift+M) and export it to sketchfab. Robot like example.

After that, the default model show the same problem ?

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Hi Carlosan,

I made it bigger and changed the scan settings.

I've just uploaded the robot example to Sketchfab and i'm seeing the same results. The full render looks great but when u view the normal map u can see what i mean. Look at the top of the face. Why is one part dark and the other light? If u look at the cube image in my previous post u can see that the normal is behaving like 4/5. 

Please check the face image. This is what I'm "used to". U can see the UV islands yet the normal wraps around neatly. This looks more like cube 2/3.robot-normals.thumb.JPG.dc207f2efd1153cadd021573ce2f151f.JPG

flip-green.JPG

normals-face.jpg

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You can add new Normal map Software presets at Preferences.

Currently, Sketchfab only supports tangent space normal mapping.

If you export a valid format with tangent spaces, we keep them.

Otherwise, if you include UVs, we generate the tangent spaces.

 

NormalMap.jpg

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Thank you Carlosan for contacting support and the preferences tip! I find the whole normalmaps thing super interesting and i'll def try to dig deeper. My colleagues use Zbrush in their workflow and when they bake normals they get the clean example like the face in my previous post. Yet the normals baked by 3DCoat work aswell however the preview of the normal looks strange. I'm getting the feeling that it has someting to do with the cubes example from my previous post....

To be continued :D 

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  • 2 years later...

Tangent Basis

Tangentseams.jpg
When shared edges are at different angles in UV space, different colors will show up along the seam. The tangent basis uses these colors to light the model properly.
Image by Eric Chadwick.

When you look at a tangent-space normal map for a character, you typically see different colors along the UV seams. This is because the UV shells are often oriented at different angles on the mesh, a necessary evil when translating the 3D mesh into 2D textures. The body might be mapped with a vertical shell, and the arm mapped with a horizontal one. This requires the normals in the normal map to be twisted for the different orientations of those UV shells. The UVs are twisted, so the normals must be twisted in order to compensate. The tangent basis helps reorient (twist) the lighting as it comes into the surface's local space, so the lighting will then look uniform across the normal mapped mesh.

When an artist tiles a tangent-space normal map across an arbitrary mesh, like a landscape, this tends to shade correctly because the mesh has a uniform direction in tangent space. If the mesh has discontinuous UV coordinates (UV seams), or the normal map has large directional gradients across it, the tangent space won't be uniform anymore so the surface will probably have shading seams.

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  • Carlosan changed the title to [Solved] Issue with Normalmap

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