Need advice on UV for vehicle - UDK

gannonroader

I'm working on my portfolio and one of my personal tasks is to make a vehicle, rig it, and bring it into udk as a driveable vehicle. I finished the model, but now i'm wondering if there is any method to laying out my UV's that I might not know before I start. Should I break the vehicle up into several seperate objects and UV them all seperately? If so which ones, and how many? I've never done this before so consider me a newb and offer any advice that you wish someone told you the first time you tried this. I'm working on a very tight deadline with all of my tasks so I don't want to waste a single minute.

Thanks a million in advance for any helpful advice


Here is my vehicle.
http://s647.photobucket.com/albums/uu192/gannonroader/?action=view¤t=LAVIII_Wireframe.jpg

gannonroader

Really? Nobody? I can't imagine it would take more than 2 minutes of your time.

passerby

just start UVing it, if you hit a problem find a different way to do it, or ask about the specific problem.

m4dcow

It maybe tempting to split the vehicle down the middle but UDK has alot of issues with those kinds of splits (Lighting, Specular etc..) even if you don't have any splits.

So you might want to overlay whole objects like the tires, hatches, railings etc...

Ken Benson

Well hopefully you're done unwrapping it by now, but...

I'd start by deleting every element but 1 that's identical (tires, hatch, back compartment, mirrors, lights, ...)
Then I'd unwrap. If you don't technically know how to do this I suggest a video tutorial search. It would take far to long to type out.

Then I copy the missing parts back in (tires, hatch, back compartment, mirrors, lights, ...)

Then go back into the uvs and separate any part that can't overlap. Usually if you are putting words/logos on the elements is when this needs to occur. Or if you are baking then you can't have anything overlap.

Then play the most amazing Tetris game of your life and get all the pieces in the 1-1 space.

Done!

Good luck!

gannonroader

hahaha Well yeah, I know all of this stuff. I guess I worded it wrong. I was thinking more along the lines of, should the commanders chamber be a seperate object, the tires another, and the body another? Should they all have their own unique, seperate materials, or should they be combined into one? For the sake of simplicity I mean. I haven't finished unwrapping it yet, but I am very close. I will have it finished today. As it stands right now, I am doing 3 seperate objects, with 3 materials, but I'm not sure if that's the correct way of doing it?

Ken Benson

Whichever way is easiest for you is generally the best way.

I try not to go above 2048x2048 textures. Mostly I stay around 1024x1024 and under. So I split things when I think the texture fidelity would be lost at a smaller resolution. Do keep in mind that 3 1024s is less space than 1 2048.

gannonroader

Oh really? That's exactly the kind of information I was looking for. I was wondering if 3 would have been too many? This is my first venture into vehicles or any object this complex, so I just don't want to do it one way and realize that doesn't work and have to start with another.

m4dcow

You also want to keep in mind that that every unique material multiplies the draw calls per shader.

Ideally you want everything on one sheet, you could also use a non square texture like a 2048*1024 if need be.

gannonroader

hmmmm, that's a good idea also. I always thought stuff like tires would be seperate because they can be used on multiple vehicles. Also the commanders chamber is a detachable piece that moves, so I thought that might also be it's own. I can do with 2048*1024 though I think. But now i'm at a conflict. Ken says that 3*1024's is less space than one 2048, but m4dcow seems to be saying 1 non square texture is better than 3 1024's?

m4dcow

I guess it comes down to priorities, it's performance vs memory usage. 3 materials will be be a multiplier for draw calls, but you may lose flexibility with one texture map.

Maybe you could do it in between, a 1024*2048 and a 1024^2 is the same memory-wise as 3 1024s, and you will have 2x draw call instead of 3x.

Instead of having just tires on the "re-usable" map, maybe you could pack a couple different accessories on there that could be used between vehicles, like guns, antennas etc...

Ken Benson

For this case specifically, I'd vote you aim for the least amount of texture calls possible. I say this because your going to be looking at the entire object usually. If you were going to blow it to bits and throw random tires all over the place, then it might be best to split it. I'm betting you can create some pretty awesome textures with one 1024x2048 for this model. Only on an HD TV would you really need something more.

gannonroader

excellent, great advice guys. I'm going to give this a try now. Thanks, and I'll post back if I have any problems.