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View Full Version : UV and Sub-D -- Arrrgh!



FenrirWolf
11-20-2003, 06:09 PM
http://www.gapingwolf.com/artwork/uvdistort.jpg

My subpatches do wonky things with UV maps!

I've gotten my butt bit by this big time, lately. I've read the Smart Maps tutorial over and over until my eyeballs neigh bleed, but I still don't get it. I've tried out the tutorial, but I end up with "patchy" UV maps after baking, where some polygons are visible and some aren't. At first I thought it was me not welding points properly, but I redid it carefully, and followed the tutorial, and still no dice.

Is there any way to get around this...bug, intentional flaw, "we-can't-solve-it-due-to-it-being-an-O(n2)" problem?

Sure, I can freeze, but I lose a lot of flexibility when doing that.

j3st3r
11-21-2003, 12:12 AM
Hi,

we had a long conversation about it with jin choung.

I suggest you few rules to keep in mind, when you UV subpatch objects:

1. Try to keep your cage as regular as possible. I mean, that avoid the too long faces, and keep your polygons equally distributed along your mesh.

2. Before UV, make a copy of your subpatch object. Set seubdivision level to 1, freeze the object, and restore your subdiv level. You`ll get a model with no subdivision, but the vertex positions approximate the subdivided mesh vertex positions. This way you`ll get less distortion.

3. UV your model as you wish

4. Use your original subdiv cage as a Background morph with this UV model, and the Apply Morph. This will reposition the freezed vertices to their original place. Delete the morph

5. Voilá, you`ve got a UV mesh, with much less distortion you`d before

The other way, using 2 plugins, UV2Morph, Morph2UV (located somewhere on this board). You UV your mesh as usual, but with this two plugin your UV will become a geometry, and you can apply Smooth, Jitter, etc modofiers, notmally you couldn`t. Especially SMOOTH can do similar results as RelaxUV in other packages.


Good luck, I hope I helped

mattbolton
11-21-2003, 10:41 AM
Thanks, j3st3r, for giving that "trick."
I finally understand how that method works. I WILL be using that idea now.

j3st3r
11-21-2003, 10:44 AM
Not perfect, but the best available.

FenrirWolf
11-21-2003, 12:32 PM
Thanks, j3st3r! Your explanation made a heckuva lot more sense. I'm going to give that a shot. :)

JDaniel
11-21-2003, 01:48 PM
Originally posted by j3st3r
Hi,

1. Try to keep your cage as regular as possible. I mean, that avoid the too long faces, and keep your polygons equally distributed along your mesh.

2. Before UV, make a copy of your subpatch object. Set seubdivision level to 1, freeze the object, and restore your subdiv level. You`ll get a model with no subdivision, but the vertex positions approximate the subdivided mesh vertex positions. This way you`ll get less distortion.

3. UV your model as you wish

4. Use your original subdiv cage as a Background morph with this UV model, and the Apply Morph. This will reposition the freezed vertices to their original place. Delete the morph

5. Voilá, you`ve got a UV mesh, with much less distortion you`d before



I did this to a couple models before and all it does is smooth out a little. Smooth tool does the same in one click. And those scripts are like Meni's tut, except automated.



I've read the Smart Maps tutorial over and over until my eyeballs neigh bleed, but I still don't get it. I've tried out the tutorial, but I end up with "patchy" UV maps after baking, where some polygons are visible and some aren't. At first I thought it was me not welding points properly, but I redid it carefully, and followed the tutorial, and still no dice.

FenrirWolf, my writing is my weak area,sorry. :o I guarantee my method gives the only distortion free method caused by that added vertice. I just wish it could be automated, it's too many steps to do if you don't understand whats happening.
Maybe you have some overlapping vertices? Besides that it doesn't matter what your uvs look like. Smartmaps you map in Layout not Modeler. After setting up your projection method Baker applies it to any uvmap you select. The less your uvs resemble your mesh,the more counter distorting the final baked image looks when viewed. But when viewed on the object it looks exactly how you projected it. If you want to edit your maps, do it on your .psd so you can save it. Then bake again.
If you don't want to deal w/ seams, don't even mess w/ an endomorf. Just front project pieces of material straight on your base object in layout, rotating where needed. (like in a 3d paint program) Use masks or incidence angles for alphas, to keep it from projecting through the object. I set my camera to a 1:1 pixel aspect ratio so I have a square map. If you're still having trouble, let me map that sucker. :cool:

j3st3r
11-21-2003, 02:09 PM
I`ve tested your method, and I found it a little problematical. At least to me. The problem is with the many extra steps. Anyway it would be interested to combine your method with the UV2 Morph script. The Morph could be use for planar projection. If you use cylindirical mapping, your UV will perfect to make a morph from it. Edit overlapping vertices, etc. send to layout, project the map, bake, paint...oh my. It would be the best, if UV would be recalculated during subdivision....

FenrirWolf
11-21-2003, 04:52 PM
Uh, one additional question -- I'm not sure what to do once I make the modified geometry from step #4. I mean, how do I get that back to my original sub-D cage mesh?

From I understand how this works, the UV map is bound to the polygons of the copy with a sub-D level 1 freeze. How can I apply that UV map to my cage?

And I'm just not getting that part about smoothing. I really hope is something that gets addressed in later versions of LW. :(

Dodgy
11-21-2003, 05:17 PM
LW 8 isn't that far off, hopefully it'll have something in there to make the process easier, even if it doesn't have UV correction in..

JDaniel
11-21-2003, 11:20 PM
Originally posted by j3st3r
If you use cylindirical mapping, your UV will perfect to make a morph from it. Edit overlapping vertices, etc


For me it's easier to unweld a seam, spread open and flatten a model in 3d space, and make a planar uvmap. Than to let LW make cylindrical uvmap and then unweld and edit in uv window. And if you want exactly copied geometry to planar projected uvmaps read the clean uv tut. at LW. The trick is to put a 1/1 square poly around your mesh while making planar uvmaps. then delete the uv for the square afterwards. Very cool.


It would be the best, if UV would be recalculated during subdivision....
Yes, like cages on nurbs, but a smooth cage around the uvs. Or merge Modeler/Layout, or add Baker and front projection in Modeler. :D

j3st3r
11-22-2003, 12:12 AM
Sure...I don`t think LW8 will solve, but I think in later whole versions will address this.

Anyway, if you use cylindirical mapping, and UV2Morph, it will deflate your model, and it will unweld the seam vertices as well.

JDaniel
11-23-2003, 10:38 PM
All I find on the search is you talking about uv2morph, but their are no links. It's not on Flay either. Where did you get it? If it's freeware post a link of it. :)

j3st3r
11-24-2003, 07:38 AM
http://vbulletin.newtek.com/showthread.php?s=&threadid=2491&highlight=morph+map is the thread.

Combining your method with this tool could be fine

JDaniel
11-24-2003, 03:31 PM
Wow, the uv2morph is really handy! Saves me some time. But the morph2uv I've been achieving by applying and reapplying a planar projection w/ nurbs activated. UVs update when reselected.
If Baker was in Modeler these 2 tech. would rock!