Uvw unwrapping channels

[Whiteout]

HI just started more in depth with making some of my own models and painting which brought me to UVW mapping/unwrapping. I believe within the UDK(static mesh editor) it states that objects should use channel 1 for the UV's for optimum lighting results. What is the difference between Channel 0 and 1. Does the channel 0 import in as a default map no matter even if I optimized a channel for use with channel 1? Also I see there are channels 3 and 4. One of the domes in UDK use 4 UV channels what are the other channels used for? Separate parts of the dome maybe layered parts? What are some common uses and benefits for using 4 UV channels...Are 4 UV channels, basically only used on domes??

[darthviper107]

Typically you've got UV channel 0 which is for your regular textures, your material. Then you would have UV channel 1 which would be for your lightmap UV's. Main difference between the two is that the lightmap UV's have to fit in the 1x1 space and there can't be any overlapping/inverted faces.

You can use other UV channels if you want to add different mapping for your textures within a material. As an example, say you've got some type of hologram character with a regular texture, you might have an additional UV channel where you can drop a panner texture so that it makes it look like the hologram has a light beam going down.

[Whiteout]

K thx that helps. I just started with a simple box and mapped with channel 1. Everything good so far except a couple minor mistakes. I imported the box into the UDK but had to use their channel optimizer to produce a channel 1 for me because I didn't export, render or bake the UVW channel unwrap properly that I made with it?? Material on the box was fine though lol

[darthviper107]

If you're using 3ds Max, it starts at channel 1. UDK starts at channel 0

So in Max the first channel=1
In UDK the first channel=0

[shuriken88]

Thats cool man, thanks, I'm gonna try something like that. Till now I've only been using 1 texture map and a lightmap channel for my models.

[darthviper107]

You can use one UV channel for both (if your texture UV's qualify for lightmap UV's) but you need to set UDK to use the 0 channel for your lightmaps, otherwise it won't render the lighting.