Uv Mapping a building

DarKMessiah34

Hey, I am faily new at modeling an was having some trouble on how to figure out how to unwrap this building.



Every time I try and unwrap it and stich all the sides the uv cordnites becomes very long so I have to scale it down considerably thus redusing resoultion. So I then tried breaking off each section of the wall in the unwrap but then I get problems with the uv's lining up.



If you notice the corners and how the bricks look bad.

Any suggestions?

Mark Dygert

Here are some quick ideas I had:

1) Use a tiling brick texture. Not everything has to fit inside the 0-1 bounding box space, its fine if bits and pieces hang way off to either side, so feel free to break out of the bounding box if you need to.

2) If for some reason you MUST have everything inside the 0-1 bounding box area. Do #1 on the 1st UV channel, so the brick tiles correctly. Then create a second UV channel where all the pieces fit inside the 0-1 space. Bake UV1 to UV2 and everything will line up and give you unique space to work with. Then you save UV2 and load it into UV1 and delete UV2.

However this often means the detail of the brick is going to be using less pixels than the tile because you're packing all those unique bricks into the same space as the tile so its a trade off. You can go with a bigger texture sheet to get the same resolution but then you have to ask yourself if its worth it, are you using all those unique pieces or would a simple tile work fine?

It's never really "how do I unwrap A building?" but "How do I unwrap this building for these set of circumstances?"

Good luck hope that makes sense and helps!

DarKMessiah34

Thanks for the help but I am confused on some parts. I can use uv's that are out of the bounding box in a game engine? I didnt think that was possible.

For example: UDK?

Eric Chadwick

I think you should learn the modular approach, it's quite powerful and it's an excellent skillset to have in your bag of tricks.

http://wiki.polycount.com/ModularMountAndBlade
http://wiki.polycount.com/CategoryEnvironmentModularity

Edit... yes UDK supports tiling. The part that might be confusing is the second UV set used for lightmapping, which usually requires you put everything inside the UV box, but only for the lightmap, it's not a requirement for your diffuse textures.

Mark Dygert

Yep, it gets used all the time, especially in UDK.

This was an example I found on the web, so ignore the writing and take notice of the pink box. It's the 0-1 bounding box space. The UV editor background has been set to display the tiling texture.


With a light map you don't nessesarily need to create a secondary UV channel and range things manually UDK can do this for you automatically however it doesn't always do the best job of using the space effiecently so at times its better to do it yourself.

The lightmap UV2 issue that Eric brings up is separate from the UV2 technique I mentioned.

DarKMessiah34

Does it also support other map styles like normal and spec? I have been learning the modular approach from the 3dmotive tutorial and other sources, but on this piece it wont really help me because its already really simple. Just seems like it should be really easy to get bricks to tile around corners :poly136:

DarKMessiah34

Thanks for the pic really helpful. So what I should do is create a tiling brick texture outside the bounding box and match up uv's of different walls accordingly?


Edit one quick question though, if I sculpt detail on each of the separate walls in zbrush, will I still get unique detail on each wall because they will be overlayed.

Eric Chadwick

DarKMessiah34 wrote: »

if I sculpt detail on each of the separate walls in zbrush, will I still get unique detail on each wall because they will be overlayed.

You cannot use a tiling texture if each wall needs to be unique.

Mark Dygert

Well... technically you can create a normal map that uses a unique UV2 or UV3 channel while the diffuse channel is using the tiling UV1 channel. It really depends on the type of damage as to how it will look. On brick, probably not so well, but I've seen a unique normal map add some much needed variation to some tiling wall sections and its kind of nice. Mostly metal, stucko or concrete.

There is a 3rd option too where you tile large sections of it and areas that are damaged are cut up and made unique.

Soo many ways to skin the same building... heh

Eric Chadwick

Yeah, didn't want to confuse the issue, as he is someone new to the process.

I think the best thing to do is to start simple, use the techniques from the Mount & Blade tutorial, with each map being a separate bitmap, like they show it.

Then once you understand that workflow, you can graduate to using a single packed bitmap for the whole building. Then, if you're still interested, you can move on to the multi-UV-channel ideas.

Mark Dygert

Yeah that's a good approach when learning.

[HP]

That Modular Mount & Blade tutorial is a gold mine, and it explains what modularity is all about really well. the 3dmotive tutorial is also recommended!