While working on the texture mapping for my Blending Life model, I kept getting inconsistent results using a bump map to create the skin relief texture. In this context a bump map is a grayscale image texture mapped to the Nor channel, creating an impression of relief on the surface, based on level of gray in the image determining the perceived height of the surface above an average “un-bumped” surface. Dark to black on the image is a “pit” and light to white is a “bump.”
As the image shows, the bump effect (left side) is not applied evenly over the entire surface of the model, some patches seem completely unaffected. The image texture shown was continuous over the entire image area, and was UV-mapped to the model.
To find out if it’s the model or the way Blender does bump-mapping, I used the grayscale bump image texture to generate a tangent-space normal map in Xnormal, and applied it to the model in the same fashion as the bump image, the only difference being that the “NormalMap>Tangent space” option was enabled in the Map Image pane of the Texture context. As can be seen there is no inconsistency in the surface effect, except a nearly unnoticeable fall-off at the extreme edge of the model surfaces. Obviously I prefer this even application of the effect over the bump map’s patchiness.
But I don’t recall ever seeing anything like this with bump maps before – I’m now using 2.46 official release , but as recently as 2.45 the bump mapping on my other models looked fine, or a least was completely unnoticeable. Has anyone else noticed this problem with bump maps in versions 2.46 or later?