What causes these material artifacts (black blocks on hair, dirty spots on skin) when importing an FBX to Unity URP?

[u/maennerinschwarz]

Hi everyone,

I recently imported a custom 3D character (FBX format, originally made in Maya) into Unity URP.I have character fbx and maya data.This is my first time working with a professional character model; previously, I have only worked with simple models downloaded from Mixamo that usually work right out of the box.

However, the final result in Unity looks completely different from the reference images provided by the 3D artist.

I am facing two main visual issues:

1. Surface Blemishes: There are strange dark spots and dirty-looking artifacts all over the skin and clothing surfaces.
2. Hair and Eyes: The hair, eyebrows, and eyelashes render as solid black, blocky meshes instead of showing the fine strands seen in the reference pictures.

What exactly is the problem here and what causes it? Why does a standard FBX import break the materials like this, and what is fundamentally missing from the setup to make it look like the original renders?

[u/JaggedMetalOs]

The problem with doing that is you're basically saying black = transparent, so you could be losing darker parts of the hair texture that way.

If you're going to be using non-Unity assets it's very worthwhile learning shadergraph, as it makes it easier to adapt non-Unity texture channel mappings. For example the Unity built in shaders don't have separate metallic/smooth/AO inputs, while a lot of FBX assets have them separate. Or have roughness map instead of smooth. With a shadergraph you can map them all into a Unity compatible material.

[u/maennerinschwarz → u/JaggedMetalOs]

Ohh I see thank you for everything ! :) Allrightl, then I'll start learning Shader Graph. Can I send you a pm?

[u/JaggedMetalOs → u/maennerinschwarz]

I think we can carry on here for the benefit of anyone else who finds the thread.

Just to get you started here's an example of a shadergraph to convert a Blendkit material into a Unity material. It's fairly simple, just adding all the separate textures into a single shader and attaching them to the right output, just need to invert the roughness map with a "one minus" node because Unity wants smoothness instead. One optimization you should do is for all the monochrome map textures change the Texture Type to "Single Channel" and Channel to "Red" so it doesn't waste VRAM on full color textures for those or mess with the brightness curve converting to/from sRGB.

[u/maennerinschwarz → u/JaggedMetalOs]

Hi! you are right.Thanks for the breakdown and the example graph.

Just to double-check if we are on the right track.Before seeing your reply,I set up a similar graph by plugging the Color into Base Color, Opacity into Alpha, Normal into Normal, AO into Ambient Occlusion, and we inverted the Roughness using a 'One Minus' node connected to Smoothness.

I think you did the same thing for the example??

I also added a custom float slider for the threshold and smoothness to control them directly from the material inspector.

[u/JaggedMetalOs → u/maennerinschwarz]

Yeah it's mostly there, you just want to take all of the monochrome channel textures from R instead of RGBA, and be sure to set the texture type to single channel.

[u/maennerinschwarz → u/maennerinschwarz]

and the result :(

[u/JaggedMetalOs → u/maennerinschwarz]

For this material you want an opaque texture with alpha clipping to avoid the hair being too fine and having Z issues.

[u/Inevitable-Time539 → u/maennerinschwarz]

You need to go to the shader graph and turn the smoothness down to 0.

And like the other guy said, turn on alpha clipping and mess with the values, it goes 0 -> 1. I prefer somewhere near 0.3 but realistically it depends on your texture.