3D models show seams in Substance Painter mainly due to inconsistent UV mapping, misaligned texture tiling, or incorrect shader settings (e.g., normal map blending).
- **Inconsistent UVs**: Overlapping, stretched, or gapped UV islands cause texture mismatches across edges. - **Misaligned tiling**: Textures that don’t match the UV scale create visible lines between UV parts. - **Shader issues**: Using the wrong normal map space (tangent vs. object) or blending mode breaks continuity.
To fix, use Substance Painter’s "UV Seam Visibility" tool to check for UV gaps/overlaps, adjust texture tiling to match UV scale, and verify shader parameters like normal map blending modes.