There is a basic Erosion function which you can use on heightfield terrains. In the Terrain layout node list select your heightfield then click Add Operator at the bottom of the list and choose Heightfield Erode v3.01. Adjust parameters to taste and click Erode Now. This can give fairly good results, but other applications will probably offer you better control at this point (e.g. World Machine, Geocontrol, etc.).
To control texturing individually for specific areas of the terrain (specific hills, mountains, etc.) you would need to use some kind of masking function, either image-based or procedural. Depending on how you are doing your texturing this may be handled in different ways, either through the Fractal Breakup input of a Surface Layer or with the Blend Shader input of most other kinds of nodes. This thread gives some working instructions for using the Fractal Breakup input to mask a Surface Layer with an Image Map:
http://forums.planetside.co.uk/index.php?topic=94.0 Once you have the basics of masking down, you would create an image mask in your image editor of choice that would constrain your texturing to the specific areas of your preference. You could use multiple image masks, one for each area/surface layer you want to mask.
There are some alternatives to this approach but I think this would be the most straightforward at this point. In the future we hope to implement a direct painting solution that would allow you to much more easily control this kind of masking from within TG2.
- Oshyan
