UV unwapping question (To Relax or not to Relax)

[EricChadwick]

UV work can be confusing and complex. Relax basically just helps to remove distortion quickly, instead of massaging texture vertices by hand. I think the right kind of Relax, ala DeepUV and some others, is a real time-saver. Some tools have bad implementations though, like 3ds max.

Some models lend themselves to straight-edged UVs. See this model...
http://www.cgtalk.com/showthread.php?t=164954
This layout helps maximize UV use, and helps you fix seams easily.

But many models don't have such easy topology, so they call for a more organic layout. Use what works best for each model. As they say, there are many ways to skin a cat.

There are many automatic-UV-layout tools. Some of the more common ones produce UV layouts called "texture atlases."
http://leigh.cgcommunity.com/site_images/dummies/part2/pt2_figureC.jpg
They typically are quite wasteful of uv space, and impossible to edit in a 2d paint program like Photoshop. But the upside is you completely avoid distortion, and you can paint using a 3d paint program.

Here's something called Pelt uvs, just starting to make its way into many tools.
http://www.sidefx.com/news/houdini_61/images/pelt.jpg
Can introduce lots of distortion, when just a circular layout like this. But might be a good starting point for further editing.

If possible, keep the same pixel resolution for all the UV chunks, to avoid resolution differences across seams. If doing UVs for games though, texture resolution should be redistributed so the areas that get the most attention (face/head/chest) would have the higher pixel density than less-important parts (feet, back, etc.).

Overpainting is also important. Otherwise colors tend to bleed into the seams, usually the result of texture filtering. So, it's good to leave at least a 4-pixel buffer in between the UV chunks, and also along the outer edges of the whole UV square. Some texture baking tools will overpaint for you automatically.

Hope ths helps.

[martinnewcombe]

Cheers for that information Eric, very helpful!

I am using MAYA and have found that Automatic Mapping is very helpful, I take it Atlas mapping is the same thing in Max!! It certainly keeps the shape of the poly's, I have also found that using the relax tool on world space is good for redistributing the polys back to there original positions when I have moved them about etc....

I have a job coming up, if you are a texture artist, its a new position for me, just wondering what a what a typical day for you is, and how long do you get to produce the uv mapping and texturing for each model, say a building or house etc...

Cheers

Martin

[Goon]

wings3d has a nice autoUV tool. Simply import your model and in object mode, select it and right click. There's a uv layout option.

Within it you can assign faces into groups, and edges to split. Then simply run the uv tool, and it lays them out.

I believe it is the pelting method or something similar, but it produces low distortion maps frequently and easily, though it might take some playing with to get exactly what you want.

[EricChadwick]

Goon, thanks for that. I'd like to check that out.

Martin, here's a thread with some info about how long it takes to do this kind of work, at least in game development...
http://dynamic.gamespy.com/~polycount/ubb/Forum8/HTML/003291.html?00036
Most of the posts are by experienced industry artists.

[martinnewcombe]

Gidday Goon and Eric!!!

Cheers for that link Goon am going to have a look at that pelt unwrapping tool!! Plus the link to the forum Eric, most interesting, seems a variety of time frames depending on the company you work for aye!!!

Eric as a Texture Artist, how much did you know about shading networks when you started, I have got a fairly good understanding but am worried that there will be stuff that is way over my head!!!

[EricChadwick]

...how much did you know about shading networks when you started...
Nothing. Learned it all on the job. But that was before the huge game development boom, even before the company was in game dev at all. So I had some leeway I guess.

I learned shaders in the 3D Studio / 3ds max product line, which traditionally has had an abstraction GUI on top-- it doesn't expose much of the mathematical underpinnings, different from the way I understand Maya to do for example. Though I haven't used Maya since Power Animator.

So 3ds max is somewhat easier I guess for the beginner, but then becomes more challenging for the expert since you need to write your own shader tools to dig deeply (or rely on third parties as I have for the most part).

Most programs come with decent tutorials and help files to explain the nodes and connections. Then you just experiment. Keep your eyes open for tutorials. Ask colleagues. Read industry journals (I like Cinefex for one). And lots of experimenting.

[Nicool]

Pelt I call it hunter method... Here is a document which makes me wanted to find a tool to do it. Byt pelting supposes to paint texture in a 3d texture app becasue of stretching problems. http://www.cgl.uwaterloo.ca/~krmoule/talks/pelt/blending.html

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