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Frank Meinl avatar image
Frank Meinl asked

Flipped normal map on symmetry

It's been driving me crazy lately and I did not find a real solution to the problem of flipped normal maps on mirrored UV when I'm using symmetry or even flipping the UV Shell. Arnold render seems to have a problem with this and everything I try ends up having more issues like puting the normal map also in the tangent slot in the material. Is this something arnold can not do, showing the correct shading when working with symmetry or even flipping the UV on tileable normal maps. Image is just a quick test to show the problem, its not really a working version.

mirrored-normals.jpg

materialsshadingnormal map
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Ciro Cardoso avatar image
Ciro Cardoso answered

Any chance you can share the door for example, to have a look? I never experienced something like that.

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Frank Meinl avatar image
Frank Meinl answered

Yes I can, its saved with max 2021 also as FBX with the normal maps, in enviroment either you can put in HDRI image or leave it empty, it shouldn´t affect the rencer view outcome.

https://www.dropbox.com/s/416gng3cxyzo6gs/door_bugsolving.zip?dl=0

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Frank Meinl avatar image
Frank Meinl answered

flipped-01.jpgBtw. even on mirror the whole object is flipping the normal map. I tried enable_mikkt in the arnold properties - it´s not doing anything. I tried also several other normal maps like objects space and world normal map, but the behavior is the same.


flipped-01.jpg (218.1 KiB)
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Frank Meinl avatar image
Frank Meinl answered

ok after further testing I guess its an Arnold thing not compensate the normal map orientation when using symmetry or mirror on meshes. In the attached image is the mesh copy/pasted with different mirror orientation and one with symmetry. So either I have to do a material for each object with flipped green/red channel or just don´t use mirror and symmetry when modeling assets? Is this something that could be fixed in the future? I might be spoiled by all the game engine renderer...

normal-map.jpg


normal-map.jpg (153.4 KiB)
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Ciro Cardoso avatar image
Ciro Cardoso answered

I have your file, but I have been super busy with work. I will try to have a look at this tomorrow.

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Frank Meinl avatar image
Frank Meinl answered

Ok, I think from what I see its all UV dependent. Bump maps have the same behavior when changing the UV direction or mirror the object. Default Scaline Render behavior seems to be correct - is Arnold getting tangent from the UV somehow?

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