How'd you unwrap this?

Piflik

Heya

I am modeling a Robot and I am currently doing the unwrap. Since I want to bake a normal map, I separated the polys with hard edges. But now I have a ton of single poly UV Shells that drive me nuts...

Here are images of the high and low and the (obviously unfinished) unwrap.





How'd you go about unwrapping this? Should I just get over it and arrange the pieces as good as possible? Or shall I go back to the low and chamfer some of the 90° edges and smooth the Vertex-normals?

Ghostscape

Apply flatten Mapping with a threshold of 45-60 degrees, then start stitching up bits wherever I don't need to have the UVs split for the smoothing groups.

With a hard-edged model like that you're going to wind up with a fair number of pieces. But you should be able to get the bulk of the mesh done as two strips - one that goes around the outside of the thing, along the direction the cylinder is curved, and one that caps that shape, with a circle on either end.

zacko9000

I would do what Ghostscape said. If you want to make texturing easier, you can also separate the UVs of different parts and lay them out. You may also want to look at some unwrapping tools like UV Layout or Unfold 3d. I use Unfold 3d and it saves so much time it is ridiculous.

Cathodeus

You can also use the tremendous plug in called Textools (for 3dmax) and the function "explode by smoothing group". That will separate uvs shell every hard edge.
This script is smart and clever. Thanks to "RenderHjs". http://www.renderhjs.net/textools/

Piflik

I know the tool and I used it. The UVs are flattened. I have stitched all I could without having overlapping faces (and without stitching hard edges...). I could have stitched the top and bottom parts to the cylinder, but I didn't want one big stripe that would prevent me from scaling my UVs properly. The thing that bugs are the many small polys that I can't stitch...

hijak

you have so many pieces from automapping it i would say would be good to just do it on a per surface basis. Just grab whatever faces you want on one UV shell and planar map them with whatever plane best fits the orientation, or in the case of the round parts use cylindrical mapping. If you end up needing to seperate on hard edges you can always do it after youve layout the uvs just go in and cut the edge, and then seperate it by 1 or 2 pixels.

Piflik

That's no automap. I selected the Polys by angle and Quick Planar Mapped them. Then I stitched. It worked good for most parts of the model, but the arms have these fins that need additional attention .

hijak

maybe don't model the fins in the low poly. They don't really show up in a silhouette.

renderhjs

would you mind sending me the low poly model that needs to be unwrapped? - I want to create a new Youtube video anytime soon and so instead I could create another video or section of it with some unwrappings of that one. From what I can see it does not look complicated and could be done within a few min. or so.

renderhjs

here is the video,

[ame]http://www.youtube.com/watch?v=4J70XVGZdww[/ame]

The steps how I see them are:

1. Split 1/2 of the mesh into UV element groups,- its all about selections - not proper UV shells
2. Then fix each UV shell portion, cut some edges (ctrl+b), relax the shell, mirror symmetrical shells
3. Normalize all shells once done with all the shells
4. Start packing stuff using the lineup tools to arrange thin and long objects together- but also to find out which elements are pairs and can be compressed nicely together.

Oh and a major reason why your mesh was so nasty was because you had a bad topology. To many double verts on places + I also noticed at least 2 triangle holes not filled proper yet. So I auto- welded the whole mesh inbetween the video to get rid of the double verts. And Voila suddenly the Shells can be relaxed the way they should.

I am just cleaning up the UV so I can post a screenshot of the final UV of how I would have things done.

SpeCter

Nice Video for your Textools renderhjs. Piflik should love you for unwrapping his model and showing a part of your great unwrapp skills(at least i do )

renderhjs

thx SpeCter

here is the finished and packed map:

one spot on the model seems to have bad topology,- I haven't looked to deep into it because I am not the modeler of that mesh. But I assume some double faces or double verts are the reason of that.
The other part I marked are the rings that are usually bendy and very nasty but I lined them up using some selection transformations and mainly the rectify button. The new lineup tools helped me there to line up verts of several parallel shells at once.

Will PM you the model later

renderhjs

btw. just out of fun I rendered together a sampe 512² texture map (smoothing groups blockout map bake + light tracer bake + wireframe bake)- that way you can better see the bleeding around the shells:

some spots are tight but mostly it works ok

pior

Are you hoping to bake those thin cylindrical fins from high to low? It will never work. Simply unwrap the low version straight, and tile a normalmap profile on it. You are creating problems where there are none :P

willy-wilson

-sigh- wish i had this for maya. uv mapping is the part i usually dred.

Piflik

Thanks for doing this.

To defend myself...the original mesh isn't bad . The double or even tripple Vertices were introduced by a Symmetry Modifier I slapped on it before exporting...it seems like the seam wasn't aligned perfectly...or the weld threshold of the Modifier wasn't right...I should have checked the mesh before exporting...where the missing triangles are coming from, I have no idea...maybe from exporting without collapsing the stack...

I noticed that you stitched many edges that are hard in the mesh (I would have done the same if I didn't want to normal map it). Wouldn't I get problems with the normal maps at these edges?