View Full Version : Baking texutres using multiple UV channels

08-17-2011, 03:58 PM
Hey everyone, kind of a noob question here. In 3ds Max i have created a high poly and low poly verison of a spaceship. The low poly has 5 different material ID's so it's all unwrapped in 5 UV channels. The problem is when I try to do a normal bake or any kind of bake it wont let me choose the other channels. I am only able to select channel 1 for some reason. What am I doing wrong?

08-17-2011, 04:41 PM
i think you misunderstand uv channels. in max having 5 material id's just tells the material which textures to use, uv channels allow you to have 2 sets of uvs for the same polygons. what problems are you having with your bake? as long as all your uv's are laid out in the 0-1 space and not overlapping it should be ok - if you look at all material id's in the uv editor thats should show you your overall uv layout.

08-17-2011, 05:01 PM
Woops I meant to say material ID channels not UV channels :poly124:. What I'm trying to do is make this low poly have 5 different 1024x1024 textures applied using a multi sub-object texture. I have my unwrap so that for each material ID the UV's are packed into the 0-1 space. But if you view all ID's than there are 5 layers of UV's overlapping.

when baking i need to be able to bake out each materal ID individually but it will only let me bake material ID channel 1 for some reason.

Eric Chadwick
08-17-2011, 05:47 PM
Using a M/S-O material with 5 material IDs is generally a bad idea for an in-game asset. This causes a lot of state changes when the model is rendered in the game, a lot of texture fetches, and a lot of draw calls. Generally a bad idea. But like anything there are exceptions. Is your asset really worth it?

RTT doesn't work on multiple material IDs. But in the Projection Options you can force it to render only one ID at a time, as long as the low ID matches the high ID. Kinda messy tho, single most of the time the borders don't match...

Still, you'll have to move the other IDs out of the UV square to avoid overlaps.

08-17-2011, 06:13 PM
Hmm, I see. Well it's not an in-game asset and it is the focal point of the scene, so I think it would be worth it to have 5 mat ID's. But if i'm gonna have to jerry-rig it like that than it might be easier for me to just detach the ship into 5 separate objects.

08-17-2011, 06:36 PM
why are you doing low polys if its not a game asset?

08-17-2011, 06:42 PM
well it's actually just a portfolio piece designed to show that I can make good in-game assets. Sooo it probably was a bad idea to make it with 5 material IDs in the first place hah

08-18-2011, 10:50 AM
Depends, 2 Mat ID's it if comes to worse, should be enough. You also could cheat most of the details via Detail maps.

Could you post up a picture of the ship and how close you plan on having your camera next/into it? If it's a HMS sized ship, which your camera will get up close and personal, and doesn't have very tilable parts, then 5 materials will be the bare minimum I would say.

08-18-2011, 10:54 AM
Just take the time to do it right. If you get a job you will be expected to deliver, if you cant you'll look like a dick.

you could probably squeeze your texture into 4 1024 maps if you pushed yourself... which is 1 2k map.

post some pics and folks can give you some focused advice rather than making guesses.