Datasmith & mikktspace tangent cause entities to glow with lightmaps

The steps above are reduced to their simplest expression.  I appears that several customers complained about lightmap baking resulting in glowing objects.  This typically happens on interior door frames and crown moldings around walls.

After digging some more, the problem is that in some cases, depending on how entities are modeled in max, Datasmith imports data in a way that tangents are scaled weirdly.

After lightmap baking, those objects seems to capture illumination from the sky - which is lot brighter than interior scenes, resulting in a "glowing" effect.

In SM Editor, you can `fix` it by recomputing the tangents .   Note that with FBX the problem doesn`t seem to occur

See this document.

more details:  [Link Removed]

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Simple steps:

Export the attached scene

Look at the tangents in SM editor

SEE: they are in a "flat" incompatible form

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[Image Removed] file:  [Link Removed]