Now if anyone has ever imported models into a game before they will have heard of shading errors, or more commenly known as bad geometry. This usually occurs when you have a model that you have imported from a different 3D program and the recreation of the mesh is not good and the smoothing is broken and the model has open faces... etc..
In essence you hope that somehow you won't have to fix it all, import the model into the game and... it's screwed...
Now there are 2 ways to go about this. Go back to the drawing board and whip out your fine editing skills and in 3D max fix the faces and shading. Now this can take a while depending on the detail of the model and exactly how bad the shading is. To be honest, even after you have done this, its not a 100% fullproof.
However there is one thing that Relic has included which will bypass these shading errors. There are 2 shaders that relic have included that can bypass the normal shading of the Essence Engine and essentially bright up each face equally, so that regardless of bad geometry or incorrect smoothing the model will look properly rendered (no black spots).
In order to take advantage of this you have to pop onto 3D max, and change the shader you are using for your model to either:
The only drawback to these shaders are that they can only use diffuse and normal maps. Additionally the general shadowing of the model isn't perfect (lack of a occluison map). However, we don't care! Since we have just saved hours of work!
Anyway, if you have any more questions, feel free to post them!