UV - optimization

Jonas Ronnegard

Hi everyone
i just wanted to ask if anyone have any tips on optimizing the UV and how i should think, i always have too much space left when it's time to put the last piece in.

also how would you go around doing uv's for mechanical objects, so far i have only done planar mapping and then linked everything together. what would a more professional person do? :P.. i know that im not being specific enough but if anyone can give me some nice tips that would be really nice.

Mark Dygert

What app are you using?

Jonas Ronnegard

ah sorry thats a good thing to tell ^^;. im using maya

Ruz

my only tip is to try and maximize space for the parts you want to show off, so its not really a maya thing, more a general uv thing.
experiment and see what works for you.

Eric Chadwick

Some things I try to keep in mind.

Reuse UVs as much as possible, by mirroring and overlapping. Place seams along natural boundries, preferrably in hidden or less-seen areas. Use evenly-sized texels to avoid different resolutions across the mesh. Avoid diagonal jaggies, try to map straight lines either vertical or horizontal. Fight bleeding by keeping a decent gutter between UVs and along edges.

But do it all as fast as possible. So ignore the rules.

nicedwar

Keep important parts generally in their correct scale, organize pieces as best as possible, and scale up what you have room for. Don't stress too much about wasted space. There's no way to account for infinite shape combination possibilities.

Jonas Ronnegard

Thanks for all the useful tips and tricks guys,, was hoping for one of those life changing answers :P but i guess there is no easy way for this one.

as for wasted uv space, companies here in sweden seems to have a uv-optimization fetish, every time i see one of their models it always looks like the model was made just to fit into the uv box :P.

Eric Chadwick

You can get as anal as you like, but at some point it's just diminishing returns, ekeing out a few extra texels doesn't really make a huge quality difference.

Try it and see, compare two UV layouts side-by-side in-game. It's easy to swap layouts by simply baking from one UV to the other. If the layout is really sloppy you can see the difference, but anal re-packing isn't actually worth the time it takes, once you see the asset "live".

Mark Dygert

For me having a layout that is easy to paint on is key to saving time and sanity. I also need to pass the assets I work on, to other people so having a good logical layout is very important. If I "need" to, later I'll repack to another UV channel and render the first channel to the second. Often for this I end up using the repacking tools, to rearrange the pieces. The end result doesn't change much like Eric mentioned and the only time its really needed is to reduce the number of texture sheets a model might be using or to resolve some back end programing issue.

I think the key thing is to remember that your UV layout isn't set in stone and you can transfer one layout to another even after its been painted. Redoing UV's no longer means having to start painting all over again from scratch. It's not a death sentence if you have to change UV layouts for whatever reason. You can have a layout that is easy to paint, and a layout that is engine friendly. Most of the time your painter friendly version is fine. The only time I end up rearranging pieces is if someone has asked me to, like, our programmer wants less texture sheets per character, or certain elements like flesh and metal separated on different sheets. Its not the end of the world and you're not Indiana Jones having to choose wisely because the fate of the world rests in your hands.

Edit: I'm talking about Max, I'm sure Maya has the same capability just named and sorted differently.