As you can see from the above picture there is a visible seam in the texture mapping. The underlying mesh is a geosphere based on octahedron subdivisions. On that particular latitude, vertices have been duplicated. However there still is a visible seam. Here is how I calculate the UV coordinates: float longitude = (float)Math.Atan2(normal.X, -normal.Z); float latitude = (float)Math.Acos(normal.Y); float u = (float)(longitude / (Math.PI * 2.0) + 0.5); float v = (float)(latitude / Math.PI); Is this a problem in the coordinates or a mipmapping issue?