Maya for 3D Printing - Rapid Prototyping
In this course we're going to look at something a little different, creating technically accurate 3D printed parts.
# 1 30-12-2013 , 05:59 PM
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UVs don't flip after mirroring geometry

hello. when i mirror geometry, UVs don't flip. they stay blue, but are not reversed. how can i reverse them? i need it for normal/displacement mapping.

# 2 30-12-2013 , 06:49 PM
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Here is a snap of the buttons to flip the UV's

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# 3 30-12-2013 , 06:59 PM
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by flipping uvs using "flip" function the uvs turn red and normal/displacement maps don't work as intended.
i have one object with maps for it. now i need a mirrored copy of that object. when i just mirror it and use maps from the original object (uvs of the mirrored object are blue, but not mirrored), the rendered result is wrong.

# 4 30-12-2013 , 07:53 PM
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How about a pic of your UV layout and the rendered result. Notice how I gave a pic and within seconds you knew it was something else. Same holds true on your side for information. Otherwise I sit here and type all day...

# 5 30-12-2013 , 08:03 PM
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here's uv layout. it's same for original and mirrored objects.
second picture is the mirrored object with applied with displacement from original one.
last one is the original object with displacement.

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# 6 30-12-2013 , 08:20 PM
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That issue is caused by the normals not being flipped, not because of the UVs.


Imagination is more important than knowledge.
# 7 30-12-2013 , 08:27 PM
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oh, indeed. i though normals were alright, because "two-sided lighting" is off, but i didn't noticed i switched to viewport 2.0.

now i have additional question - how can i mirror an existing normal map for that case?


Last edited by mickhah; 30-12-2013 at 08:34 PM.
# 8 30-12-2013 , 10:25 PM
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i tried to invert green channel in photoshop, but got this result:

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# 9 30-12-2013 , 10:35 PM
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XNormal -y conversion. Game engines require the alt setting in some cases so I have to batch this out of Crazybump. That costs money. But XNormal is free and will do it as well.

# 10 30-12-2013 , 10:44 PM
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as i understood, i have to load high- and low-poly mesh into xnormal and switch +y to -y there. is there any way to invert already existing normal map, rather than render it anew?
i tried to export new map from zbrush with inverted green channel, but still have seams like in the last picture.


Last edited by mickhah; 30-12-2013 at 10:54 PM.
# 11 31-12-2013 , 12:41 PM
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solved....

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