UVW Unwrap

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  02 February 2013
UVW Unwrap

hello! I have some very large models that I would like to bake textures and bring into a game engine.



What I was hoping to do was attach all of the objects together > apply uxw > box > and unwrap the 6 sides. When I do that, I get a huuuggee f'd up mess. There are way too many objects to unwrap each one and attaching everything and sorting the mess looks to be impossible. I am a newb to unwrapping but understand the concepts and operations involved in UVW mapping.

I was thinking of writing a script that detached all faces where the normals pointed toward each side of the box but if there is an easier way, I'd love to hear it!

How would you handle unwrapping this monster?
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  02 February 2013
Well to be honest you're kind of going to have to unwrap it all. Box mapping will help for boxy stuff, but for the chimneys you need cylinderical mapping and planar for some bits. You need to treat each item individually.

Peel is pretty handy for unfolding boxy stuff like railings and stairs.

I would definitely NOT attach it to start with though. Sorting through the mess will take forever. You're better off with separate objects that you can select, view and map individually. Then attach when you're done and lay out if you need them all on one map. And for something like that you're more likely to need multiple tiling textures than one single one anyway.

Really, it's too late, but it's MUCH easier to map as you make things like this. It'll be full of repeated objects like railings. Why map them all at the end when it's much quicker to map the first one before you clone it lots of times (or even better instance them so you only ever need to work on one).

You might even find it's easier to map one, delete the others and replace them with the mapped version. Do it one section at a time to keep track.

This is not a good model to be learning with I'm afraid. You have my sympathy. Good luck.
 
  02 February 2013
I think you should bake the bigger, simpler stuff, get a nice texture on those and try and do the rest(like the rails) as a procedural in the game engine. there's just too much stuff otherwise.
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  02 February 2013
Thank you for the replies!

The models are definitely gargantuan but many of the objects are simple primitives and since I import them from dwg, some of the objects even come in as instances which would also save a lot of time.

Whatever I do has to be scriptable. This is one model in a few hundred to a thousand on any given project. I was going to try to iterate through each object, check if there were other objects exactly like it (bounding box?) and adjust the UVW settings based on it's layer name. Maybe time to run a few tests!
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  02 February 2013
3ds Max has an automatic unwrapper, it separates faces by angles which doesn't make an idea result, but it does work so you wouldn't have to do each little thing. It can be an issue in game engines though where you need a good UV unwrap otherwise when it switches between texture resolutions (as many engines do automatically) it can end up with seams on the UV edges where pixels have become bigger.
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  02 February 2013
Originally Posted by em3: Thank you for the replies!

The models are definitely gargantuan but many of the objects are simple primitives and since I import them from dwg, some of the objects even come in as instances which would also save a lot of time.

Whatever I do has to be scriptable. This is one model in a few hundred to a thousand on any given project. I was going to try to iterate through each object, check if there were other objects exactly like it (bounding box?) and adjust the UVW settings based on it's layer name. Maybe time to run a few tests!
Gees, that's a ton of work.

Are there any corners you can cut on this? For Example if this is monocoloured you can easily bake a lot of things like AO in to the vertex colour or bake a simple dust pass.

You can also split up the moddel in to two or three objects like rails, metal surfaces and painted surfaces, UVW unwrap each automaticaly and when you bring it in to the engine they'll have their own three or four shaders to share.
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  02 February 2013
This sounds like a very atypical workflow for games. Are you using a game engine for arch vis? I've never heard of actual game art being done like this. We make it right in Max taking UVs into account. Every single triangle in a game world needs UV normally.

If there's a lot of these, but they don't need to be seen up close, then yes auto unwrap them. You'll get terrible UVs but there's really no other way. Have a look at the options in the UVUnwrap editor menus. Flatten will probably do it.

With auto unwrap you won't get much texture resolution as it's very wasteful. But if it's not for an actual game you might be able to afford to use giant texture sheets.

Procedural textures don't really get used in games. Too slow and look bad. You usually need the detail from proper textures to apply things like dirt. What engine is it? Procedural might be possible in some. Usually it's only used for water and skies where it needs to animate.

Another alternative is a tri-plane shader which basically projects textures from three world axes and blends them based on the normal of the surface. It's usually used for difficult to map organic objects. It was used in the Ant Lion tunnels in Half Life 2 ep 2. I made a shader in Max to do it using ShaderFX.

Edit: Added a screengrab of the tri-plane shader test I made.

You'll still need to break it up into different materials though and nothing would align with the actual geometry. It'll all be tiling.

Or simple flat colour where possible.
Attached Images
File Type: jpg blend_world_axis_shader01_resized.jpg (72.3 KB, 7 views)

Last edited by robinb : 02 February 2013 at 01:31 PM.
 
  02 February 2013
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