so i have some issues with bump mapping meshes made in maya.
using tangents/bitangents generated by maya or generating them myself gives me pretty much the same result.
here some screenshots showing the light vector (light source is at {0, 50, 50}) in tangent space with tangents from maya and self-generated:
i'm pretty much out of ideas atm. 
i generate my tangents/bitangents like described here:
http://www.terathon.com/code/tangent.html
just in case here is the code:
using tangents/bitangents generated by maya
What are you displaying? Tangents, or normals? You should compute binormal as cross porduct of tangent and smooth normal, then display to yorself smooth normals and binormals, those should be smooth, tangents are never smooth. Tangent are equal for all three verticies and are of very triangle plane contained.
using tangents/bitangents generated by maya
What are you displaying? Tangents, or normals? You should compute binormal as cross porduct of tangent and smooth normal, then display to yorself smooth normals and binormals, those should be smooth, tangents are never smooth. Tangent are equal for all three verticies and are of very triangle plane contained.
if you mean the picture, that is the light vector in tangent space.
normals:
tangents:
bitangents:
bitangents seems incorrect (they should be smooth). Normals are definetly correct, compute the bitangent as the smoothed normal and tangent cross product and display them- if they show smooth, you are all set. And should nat pay attention to tangent vectors not being smooth at all (they never are)
Remeber there are two types of binormals, the one that is truly orthogonal to tangent/ and the one that is cross porduct of the very tangent and of the smoothed normal. The second is wanted , so compute it yourself, and do not pick it from asset defintion, as the asset usualy delivers the real bitangent (the truly orthogonal one- not desired for lightining)
are you sure the tangents are correct ?
because on top of the head there is this weird area.
are you sure the tangents are correct ?
because on top of the head there is this weird area.
That is the seem, they appear where inconsistent mapping happens. it still can appear in your spectating shader, but should not affect lightning if you use correct handedness of tangent. Stop doubting maya generated tangents finaly
ok i guess the pictures in the first post might not show the problem clearly, so here are pictures of diffuse nDotL.
maya generated tangents/bitangents:
self generated tangents/bitangents:
the light comes directly from the front.
as you can see the result is partly wrong.
now maya gives you the handedness of the tangent, and i do have some that are left handed, but i don't do anything with that atm and just leave them as they are.
when i generate them myself i compute my bitangent with: cross(n, t) * handedness.
i just exported the normal map in object space, and this is what i get: 
