That is good to hear. I encountered it on a few of my handplane bakes too but just rolled with it and painted them out. It was a small cost for the overall ease and accuracy of the workflow.
Big thread bump. Several months of messing with this issue only to find it is somewhere between a non-issue and unfixable. Basically, source engine tangent space doesn't split tangents across any sharp angle threshold (talking tangents, not normals). As a result, it is possible for the mesh's tangent to face the opposite direction of the mesh's normal (resulting in those patches of off colors). You can go into your normal map an manually invert those pixels to get nice contiguous looking colors but that is not actually correct for what the engine is expecting and you will get severe shading errors in those spots. Here are some examples:
On the top is a 'corrected' normal map that looks good in Photoshop but looks bad in dota. On the bottom is the output straight out of our handplane xnormal beta plugin. http://i.imgur.com/rhxnYLG.jpg
You can still get very light artifact surrounding these areas which appears to be the result of the texture filtering interpolation between the two extreme colors. In most cases you probably won't be able to see them in game, but if you do you can add a smoothing split in that area to relax the shading and negate the problem. Also, the way 3dsmax calculates mesh normals seems to create this effect less often maya.
Replies
On the top is a 'corrected' normal map that looks good in Photoshop but looks bad in dota. On the bottom is the output straight out of our handplane xnormal beta plugin.
http://i.imgur.com/rhxnYLG.jpg
and another
http://i.imgur.com/syFXCAi.jpg
You can still get very light artifact surrounding these areas which appears to be the result of the texture filtering interpolation between the two extreme colors. In most cases you probably won't be able to see them in game, but if you do you can add a smoothing split in that area to relax the shading and negate the problem. Also, the way 3dsmax calculates mesh normals seems to create this effect less often maya.