how to procedurally generate "high altitude" terrain textures ?

Hello, I am looking for a way to procedurally generate ground / terrain textures as they might be seen from high altitude (e.g. from an airplane)
I mean those differently greenish-brownish colored and more or less randomly shaped patches of a landscape, which mostly are human made(?)
The Voronoi texture with minkovsky algorithm and a larger exponent and with position coloring and “shifting” the values to green / red tones could make a first approximation for that.
But in blender (2.4 and 2.5) ui they do not seem to have a random seed (dunno how this is via python api) so each time i create a new voronoi texture the outline positions /shapes and even the colors are the SAME ?
Is this a feature or a bug ? Anyway, i am already experimenting with MapZone 2.6 (great free procedural texture generator, but unfortunately no direct Noise generator functionality (and no random voronoi) and worst, NO open source so not extendible. A python clone of this would make very valuable blender addon indeed … but as said, no source, no fun. :frowning:

My goal is to create many of those “terrain patches” which should ideally form the “lower” part (as seen from space) of a planetary surface which should pop up when you get closer to the planet and replace the “one-piece” planetary surface.

This should work in an animation in the first place and ideally interactively in the game engine.
Sort of a “low altitiude celestia”.

Hope you understood what i mean…