Whats causing this?

#1 It might be the specular cutting off when the surface is backfacing from the light. See if you get the same problem without specular, and whether this happens only at certain angles between the model, the camera, and the light.

FYI, I'm going to be changing the specular so it fades out instead of popping when the surface backfaces.

#2 Well i exported to .x then re exported to dts and it seems to have cleared up alittle..any eta on the fade or is it something i can change in the shader..lol

#3 It's a really low priority, so prob not too soon. You can change it in a shader, yes. I think it tests if the face is backfacing the light in the vertex shader and it passes a multiplier to the pixel shader to mask it out if necessary.

#4 This may not be related, but sometimes I see that on meshes when importing / exporting a lot between applications, the node become unwelded and gives this very similiar effect (due to the mesh thinking the end of the mesh is along that seam), if anything it may be something to double check out if no other thing is found.

#5 I've been having issues that looks something like that. On a model made in blender i imported it to torque. All by itself, all was fine but when i put a normal map on, ANY kind of normal map at all, i got lighting that looks something like that.
The shading was horribly ugly and choppy all over and at different sections of the skin, like where the front peice of the skin ends and the back begins, the lighting changed altogether from dark to light or other way round. I haven't been able to find whats wrong and i've had my modeler check everything that could be it, even re-unwrapping the model, still no success and this looks is very far from acceptable.. Perhaps these issues are related? I'll post a pic of it if ya like.

#6 I don' t think this particular problem is normal-map related.

Jacob - are your normal maps in model space or tangent space?

#7 Tangent. And as i said, the normal map doesnt matter how it looks. I tried a normal map of the model, screwed it up. Tried the orc's normal map, screwed it up. I even took a blank normal map, one with no detail at all, screwed it up. Its any normal map. Fine without a normal map but screwed with it. :/

#8 The problem is the model data normals from exporter, the same model exported from 3ds max will work fine.

#9 Hm.. K. i'll try to get it exported from 3ds max soon, haven't had much luck with it though.. Im wonderin why that happens too. Without a normal map the normals are fine but freak out with a normal map.. *shrugs* o well..

#10 Yah, from what i can see it is defo something to do with the normals from the model. I saved the model as a .x file then re exported from GS and these hard edges went away. BTW this is a model taken from POSER, so there is no telling whats going on.. As the model seems to have these edges in GS as well.Models that i have created from scratch do not exibit this behavior.