I have been making a model for the Source Engine, I baked a normal map and gave it a simple test diffuse texture (Solid colors, very basic with no shading). In blender everything seems right

Model without the normal map

Model using normal map

However, in game the seams look very obvious, an the UV islands appear to have different lighting. Some are darker, and some are brighter.

[Front of the model in-game Back side of the model in-game

Many solutions have been tried, I looked trough the Source Developer Community, and found that the normals need the Y channel to be inverted, and while it didn't solve the problem, the normals now look fine. Normals also need to be using tangent space, and the normal was baked that way. My guess is that it could be the UV island orientation, I found some sites claiming that it was important for all the islands to be facing the same way, but I havent tried that. Unwraping the model again would be hard, since the low poly mesh has been modified since the bake, so they wont be aligned perfeclty.

Is there anything else I need to do? Thanks in advance

  • $\begingroup$ Any chance you could post the Blend file? $\endgroup$ Feb 17, 2020 at 4:05
  • $\begingroup$ we.tl/t-x31zOp0Xwd Here's the blend file plus the 2 textures (blend file had more stuff, but I removed the unnecesary stuff to lower the file size) $\endgroup$
    – Skessler
    Feb 17, 2020 at 5:32
  • $\begingroup$ Unity and Unreal are also handling the normal maps differently and in Blender you also have to switch the colorspace to non-color data in the shader editor to work well. Probably you have to adjust something on the image in the game engine. $\endgroup$
    – FFeller
    Feb 17, 2020 at 7:33

1 Answer 1


I'll say it this way: the problem for me was in the colorspace. Thanks FFeller!

  • $\begingroup$ Colorspace OK, but what exactly? Give details, please. $\endgroup$ Aug 29, 2021 at 9:47
  • $\begingroup$ color → noncolor $\endgroup$
    – Goury
    Aug 30, 2021 at 10:27

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