This is taken from a post I made a long time ago in the CT forum. (*Note that bump maps are not currently used. At this moment we are not sure what the outcome is going to turn out like with them):
Terrain tiles are now 512x512. They are still 256 colors. Also the naming convention and number of tiles has changed. There are now 4 types for every main tile texture.
For example, you would have one grass texture and then 3 other modified versions of the grass texture.
The edges of the sub-textures must always match the main texture. The new naming convention is as follows (using texture 1 for example):
terr0001.bmp
terr0101.bmp
terr0201.bmp
terr0301.bmpRight now, the main texture numbers go from 1-6 and 16 (snow in AH1). We haven't determined how we're going to do beaches yet.
All transitions are now done with an alpha, and there is only one transition texture per main texture type. The naming convention is the same as above, except using 'tert' instead of 'terr'; along with '_a' at the end. For example:
tert0001_a.bmp, tert0002_a.bmp, etc.Bump maps are grayscale. Basically, you can take your regular textures, and set them to grayscale. It is best to start this way in order to exactly match the texture it is associated with, and then adjusting areas for more/less bump mapping. Black=no bump, and white=full bump mapping. The naming convention uses 'bump' at the beginning. For example:
bump0001.bmp, bump0101.bmp, etc.Please keep in mind that the format in which terrain textures are made could be changed, so don't get mad if that happens.

The most likely thing to change would simply be naming conventions of the files, however nothing is set in stone at this point.