just a note: when using the maps in object space, the objects can rotate and still maintain proper shading: http://wiki.polycount.com/NormalMap?highlight=%28%5CbCategoryTexturing%5Cb%29#Object-space_normal_map
From reading the wiki linked by Racer445 it would seem tangent space normal maps would be used most of the time (which they are..), but the limitations of Object Space do not seem that horrible to me? I'm sure there would be some circumstances where using an Object Space map would be better than tangent? I'm no expert at…
I think they did it to avoid seams between the head and the body. I haven't experimented with object space in that game, but if you can use them for custom models it would be pretty cool :D
Object space maps can be made to work with deformable meshes. 8 Monkey labs did it in darkest of days I'd say non bone deformed meshes would indeed be problematic though
object/world space normal maps also do not work with deforming models so characters or props with skinned moving parts or props/vehicles that use blendshapes for damage deformation etc. have to use tangent space normals.
Tangent space normals are a comparison between your high and low poly's normals. so the Normals of both directly effect the result. The gradients are correct and should be present. the thing is Unity doesn't do normal maps the same way as topogun (neither is wrong, and this mismatch is a very common problem, its a math…
Yeah more like 99% of the advantage. =P Correct, there was also a Battlefield(BF:Vietnam?) game that used OS maps exclusively for character meshes.... Just throwing that out there before someone pops in and says "oh but you can't use it for soft deformation". You can animate object space maps just as well as you can…