Blog Patrol

Saturday, 28 June 2008

Education : no31 'Colour Map'
This is one of the more newer maps that texture artists use. I often come across people that have never heard of such a thing so I will just explain it's purpose as simply as possible. You should open up the following image while reading this.

1. So imagine this is say 3% of your asset. 5 plains that share the same UV's and texture. It tiles but it sort of looks bland.

2. On UV channel1 the UV's are 5 boxes overlaying each other but in another channel (usually 2 or 3) we have UV's for multiple parts. We make them so small so there is room to have a unique face for each plain. This is to be the colour map and is usually 1024 or 2048 pixels.

3. This is a zoomed in view of the top left corner of the UV map. The rest of the map will be filled with all the other parts of the asset, I'm just not showing them here.

4. Very crude but hopefully it puts the idea across which is that you can paint unique details onto each plain.

5. So now all 5 plains do not look exactly the same.

The whole process really is just an alternative decal method. I almost always have colour maps now for every medium or large asset.


ejay said...

How are these two maps (hires base texture + lowres variations) being mixed on the final plane?

And if you actually used decal objects, wouldn't you have better control over the placement of the dirt elements, as well as the ability to use different normal/spec maps on them? (for example- adding a cracked area to an otherwise smooth wall)

Anonymous said...

Hm i didn't understood what you mean with that article...what's the new about a unique mapping?

caponeart said...

Hey ejay,

Decals are good if you just have a few specific areas to place a few specific decals but for large general areas it's much faster to make the changes in one single texture map. But yes so far the problem is that with the engine I'm using we're not able to create normals / spec but again this map is only for subtle texturing. You can't for example do cracks in a colour map as the density will likely be too small.

As for how to apply it. We have a custom shader that has a unique slot for it. You can still do it with a standard material in Max by using a RGB multiply shader and then place diffuse in 1 slot and colour map in the other then in the colour map slot make sure UV channel is set to correct one. The downside of standard material is that it only shows the colour map in renders and not the viewport.