View Full Version : UV Mapping of Subdivision Surfaces

08-28-2014, 11:16 AM
Are there any native workflows (or work arounds) for correcting UV maps on Subdivision surfaces, or will I have to invest in a 3rd party tool to do the job?
(I have 3D-Coat, but I can't see anything about correcting for Subdivision surfaces...)

08-28-2014, 11:46 AM
What do you mean by "correcting". Is setting the map type to subdiv in Vmaps panel not what you're after?

08-28-2014, 08:03 PM
if you're talking about the UV interpolation part,

then no, no easy way... (at least afaik)

I have 3D-Coat, but I can't see anything about correcting for Subdivision surfaces...

do you need to? shouldn't 3D-Coat just simply make a UV map, for then to be imported into LightWave correctly ?

08-28-2014, 08:36 PM
old http://forums.newtek.com/showthread.php?100351-3D-Painting-Seamless-Rendering-UV-maps-for-Subdivision-Models

08-29-2014, 12:06 AM
Since pictures are worth a thousand words...
Here's the unsubdivided geometry, with a simple UV map applied to the top:
http://img.photobucket.com/albums/v636/Kryslin/Tech%20Stuff/drain-unsubd_zpse8ac0bec.png (http://smg.photobucket.com/user/Kryslin/media/Tech%20Stuff/drain-unsubd_zpse8ac0bec.png.html)
The UV Mapped texture is nice and undistorted.

However, when I subdivide it...
http://img.photobucket.com/albums/v636/Kryslin/Tech%20Stuff/drain_subd_zps7804ff8f.png (http://smg.photobucket.com/user/Kryslin/media/Tech%20Stuff/drain_subd_zps7804ff8f.png.html)
The UV texture is badly distorted.

I've got no problems generating a UV Map - 3D Coat does a wonderful job of that, and so does the trial version of UV Layout I've used. It's compensating for the distortion in the second image that is driving me nuts. Is this correctable within Lightwave, or am I going to have to find another program to sort this out?

08-29-2014, 12:20 AM
Note : Trying Probiner's method in the old linkage gives the distorted results.

08-29-2014, 12:58 AM
Simply make the UV map in LW, set it to sub-patch, export that map and apply texture, it will work fine. Or if you already have a map generated, open it in LW, change it to sub-patch and export it and apply the texture.

08-29-2014, 03:08 AM
Yep... set the map to subd in vmaps panel.

08-29-2014, 05:58 AM
Both 3D Coat and UV Layout are aware that you have a subD mesh so they distort the points to subdivision level one. Meaning, no actual division, but the cage points go to their subd positions. This will give you polygon with an area mush more approximated than the end polys so the relaxing and area routines will match much better.
LW doesn't care for that, hence the complicated videos I did on the matter. Mainly because I don't like to rely 100% On UV interpolation because it has no relation with the 3D space meshes, it's just like applying to subdivision to the UV mesh and not every package solves seams corners the same way LW does, Linear is usually a more solid solution to jump a mesh around. Plus sometimes I prefer to use maps where 1 polygon = 1 island and interpolation helps 0 in those cases.

On your case, looks very simple. Indeed you just need to switch from Linear to Interpolation like the others said, like so: https://www.youtube.com/watch?v=p3sb_WHUeWU&t=1m

The last video I did about doing it all in LW: https://www.youtube.com/watch?v=GxiJo_nt5J0&list=UUsjPx76I1QJRJt8bBBsDE9Q
But if you have 3D-Coat, just use it :D


08-29-2014, 06:22 AM
Kryslin, in this case it's rather easy http://erikalstad.com/backup/misc.php_files/047.gif

just project the image in the Y axis in Layout, then Camera bake it.
apply the baked result onto the UV map... (see image)


just need to switch from Linear to Interpolation like the others said
this is also a good solution, but if you want to send it to another 3D application i think this could cause trouble...


08-29-2014, 08:22 AM
What am I not getting? Here is a subdivision disc with sub-patch UVs made in Lightwave and how it looks in three other 3D programs.


I don't see what the complication is.

08-29-2014, 10:29 AM
Well this is a fairly simple case, right? A flat open mesh. Definitely Kryslin was missing the Interpolation.

In the following image though, two points are highlighted:

A seam corner is the point where a seam ends inside the mesh (not in a hole/open border). Softwares solve this corner differently. So after you get your textures done, if you're painting in a 3D painting package, you'll need to fix it afterwards.
A polygon corner is when a seam finds a hole, so you get two segments of the UV border going around the same polygon. Not all packages do "Smooth but keep corners linear". Some do Linear Edges, some Subpatch (Smooth), some Linear Corners (the best).
So if your model asset is jumping around relying or interpolation has it's restrains, that's the complication. Better just freeze it with 8 divisions (Supatch 8, Catmull 3) if you want to play safe and have the textures from the 3D painting package match seamless when you use them in LW.


https://dl.dropboxusercontent.com/u/143766132/Infographics/UV_Comparison_tn.png (https://dl.dropboxusercontent.com/u/143766132/Infographics/UV_Comparison.png)

08-29-2014, 10:48 AM
Probiner, wow thank you very much for your SubD explanations, I wanted to ask you to post a compilation of your maps but then I noticed your great wiki on your website. Your work should be a sticky thread in this forum. Great reference to print and hang above the 3D workplace!

08-29-2014, 11:32 PM
I would like to thank everyone for their assistance; From what I can see, the interpolation type makes very little difference - I can't even see the UV map (just points) when the interpolation type is anything but linear - seriously. No matter what I've tried, I still get that distortion. However, altering the geometry itself, along with setting the interpolation to subpatch (as advised) helps minimize it to a level won't be noticed,

And it will be a long time coming before I do this again...

08-30-2014, 04:08 AM
Ingenious stuff, thanks :)

08-31-2014, 12:27 PM
Here's the final result... it appears I agonized over this for nothing, because the end result is hardly visible. :)
http://img.photobucket.com/albums/v636/Kryslin/Renders/th_sink2_zps169f8535.jpg (http://smg.photobucket.com/user/Kryslin/media/Renders/sink2_zps169f8535.jpg.html)

Anyway, thanks to everyone for the help.

08-31-2014, 12:47 PM
By your description of the UV Space, it just hit me... You're using Catmull-Clark!

UV mapping is usually wrong anyway, we just try to keep it to imperceptible levels with more divisions, though some wrong stuff still goes in each division :)