FBX and normals

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Hey,

I'm having probs getting the FBX exporter to export the normals correctly on a deforming mesh.
Try this:

1:lay down a poly grid.
2:connected that to a point sop
-with random translation in Y eg: $TY+(rand($PT+$F)*.2)
-change the normals from default to point in another direction

3:promote the normal to a vertex attribute (for Maya)
4:export as FBX using the “detect constant point count” option ON.
(otherwise it triangulates the geo)

When this is imported into Maya the normals do not match the houdini ones. They're the default normals.

Am i missing something here?

I've attached the hip file and jpg of this
Cheers
Pav

Attachments:
forSFX.hip (92.7 KB)
normalsAndFBX2.jpg (43.6 KB)

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This looks like it might be a bug in Maya's FBX importer. The trigger seems to be promoting normals from points to vertices in Houdini - if you leave normals assigned to points, they import correctly into Maya, but if you promote them, the default ones are created instead.

The reasons to think this is something on Maya's side is because:
1) The correct normals are exported to the FBX file itself, as can be verified by looking at its ASCII version.
2) If you import the same FBX file with normals promoted to vertices back into Houdini, they will import correctly.

Fortunately, the easy solution seems to be to avoid promoting normals to vertices and they will import into Maya properly.
Oleg Samus
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Side Effects Software Inc.
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oh.
What version of the maya FBX importer are you using?
Any special settings?
I'm still getting the default normals..although it now looks like this:

Thanks
Pav

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normal_point.jpg (32.7 KB)

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Well, turns out there's more to it.
The workaround I suggested earlier solves the problem only for static objects, not for animations. With animations, it looks like Maya overrides the normals anyway, despite them being properly stored in the FBX file itself. This happens both in 2009.3 and 2010.0 FBX Maya plugins.

Perhaps one (admittedly painful) solution would be to import a static mesh first, then import an animated version of the same mesh, and then re-assign the normals from one to another.

Alternatively, have you asked Autodesk about the issue, since it does seem to be something on their end? Perhaps they can provide a better workaround or simply give us more information about why this could be happening.
Oleg Samus
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Side Effects Software Inc.
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It's a maya FBX bug.
Autodesk is looking into it.

Cheers
Pav
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Any updates on this?

pgrochola
It's a maya FBX bug.
Autodesk is looking into it.

Cheers
Pav
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