The Normal Map or Bump Map channel uses a texture to add bumps, dents, and other details to the surface of a model.
Currently, Sketchfab only supports tangent space normal mapping. Other types of normal maps like object-space or world-space normal maps are not supported, and using them can produce unexpected results on Sketchfab. If you export a valid format with tangent spaces, we keep them. Otherwise, if you include UVs, we generate the tangent spaces.
Enable Invert Y to reverse the bumps and dents, depending on whether your normal map was created based on OpenGL or DirectX.
We expect DirectX (Y-) normal maps by default, so if you're using DirectX, you should not need to change anything, but if you're using OpenGL (Y+), you'll need to flip the toggle in 3D Settings.
A bump map is usually a linear grayscale image.