This is an example of a 1024x1024 USGS DEM file converted to a grayscale tif & displaced to an AnythingGrooves plane in Carrara V1. The color shader has two nested color mixers, bumps and an overall Glow channel mixer useing Black & White colors that are mixed with an Elevation in the X axis (front to back) to wash out the colors towards the distance. The tree was added in Painter with a nozzel (Digarts Jungle 3D). I didn't bother with the Glow channel on the river. I believe that litst has a few shaders in the marketplace here and there were several at the Carrara Yahoo list done by Dan and a couple others. The procedural shaders will slow down your renders if they become too complicated.