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[Reopened] Several Displacement Map Bugs


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Heya!

I spent the whole day fiddling around with Ptex-sculpting (which is NICE!) and then baking to a handmade UV set to finally render in Softimage / Arnold.

I always got crashes and/or seams and started to wonder whether I'm just too stupid to find the right settings (e.g. for the UV smoothing etc.).

Now after checking again and again in different apps (Mudbox, Softimage, Houdini, ...) I found out that it's not entirely my fault, and here are my findings:

- 3D-Coat adds NaNs (not a number / illegal values) inside 32bit EXRs when using padding. At least when setting the mode to "Black is zero, not normalized". This crashes most renderers or at least causes spikes along seams... which leads to bug number 2

- I always get seams along UV borders, no matter what UV smoothing mode I use. I reconfirmed this in all the apps I mentioned above. In the end I tried loading the output OBJ into 3D-Coat itself and import the displacement map and even there are seams. Looks like 3D-Coat somehow messes up UVs while exporting. The strange thing is that UVs in 3D-Coats "Texture UV Editor" still look correct, while they produce results as if the UV island were overlapping the seams a tiny bit. This in combination with the NaNs makes it impossible to get clean displacement maps directly out of 3D-Coat.

Thanks in advance, Andrew

debris

P.S.: This is all 3D-Coat 3.3.12 latest x64SIMP build on Win7 x64

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Have you tried using gray as zero? How did you get the texture?

I'd like to work with not-normalized floating point EXRs so I don't have to find out the normalization factor when rendering. No I didn't try that option.

I exported the texture using the "Export Model" command.

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You are awesome! :)

OK, quick update on this one. The padding NaN problem is fixed, thanks Andrew!

Now I have another problem related to padding. I have to use a "1 poly = 1 UV island" UV layout to get undistorted results in Arnold and Houdini (and maybe in every other renderer that uses Renderman compatible UV smoothing... I'm still trying to find the correct UV smoothing option to use handmade UVs directly). So far so good. I just noticed that even in the 3D-Coat viewport I get visible seams after baking a Ptex object to microverts. I found out that the new padding seems to bleed into neighbouring UV islands (see screenshot) where it shouldn't. The UV island are close to each other (roughly 4 pixels of space for a 2048x2048 texture) but don't touch each others. Padding should ideally meet in the middle between two islands, but shouldn't ever bleed into "foreign territory".

Cheers & thanks again

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So what now? Is your problem solved or not, please?

Please adjust subject line if needed, please.

No, my problem is not solved... and I can't change the subject line as I'm not an admin / moderator...

Sorry, if my description was unclear or the 2nd posting with the Ptex UVs made it unclear. In Ptex mode everything is fine, in other modes padding bleeds into neighbouring UV islands.

EDIT: Hey Taros, could you please change the subject of this post back to "unsolved" or whatever? Or would you recommend me to open a new thread for it?

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OK, quick update on this one. The padding NaN problem is fixed, thanks Andrew!

Now I have another problem related to padding. I have to use a "1 poly = 1 UV island" UV layout to get undistorted results in Arnold and Houdini (and maybe in every other renderer that uses Renderman compatible UV smoothing... I'm still trying to find the correct UV smoothing option to use handmade UVs directly). So far so good. I just noticed that even in the 3D-Coat viewport I get visible seams after baking a Ptex object to microverts. I found out that the new padding seems to bleed into neighbouring UV islands (see screenshot) where it shouldn't. The UV island are close to each other (roughly 4 pixels of space for a 2048x2048 texture) but don't touch each others. Padding should ideally meet in the middle between two islands, but shouldn't ever bleed into "foreign territory".

Cheers & thanks again

It looks like distance is only 2 pixels. Why not make it wider? What about ptex - it is handled very specially, this method can't be used there.

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It looks like distance is only 2 pixels. Why not make it wider? What about ptex - it is handled very specially, this method can't be used there.

Thanks Taros, thanks Andrew! :)

The distance "should" be at least 4 pixels, according to the settings in Softimages "PolyPackUV" operator. I will re-check this. How many pixels does it need at least? I don't want to waste precious UV space with black holes ;)

Cheers

Steffen

P.S.: I would rather use a more contiguous UV layout but I'm still on the search for the correct UV smoothing setting in 3D-Coat. While "Smooth but keep edges" works supernice with mental ray's UV smoothing, it seems that none of the 4 settings is the right one for Arnold / Houdini / Renderman (they all share the same UV smoothing AFAIK).

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