I'm not sure if this is the right place for this post, but I'm looking for help in finding suitable terrain generating and editing software that runs in Windows 7.

I will be using it to create a very large terrain for use in a 3D game engine (I'm not 100% certain which one yet) which the player can walk around on or fly over at low speeds. It would be handy if it could create terrain for an entire planet, so that I can then choose which parts to export.

I would like it to automate as much of the process as possible, so that minimal work is required after the terrain is imported into the game engine (as I'm not sure it will have its own terrain or object editor).

It should have the following features as a minimum:-

• Runs in Windows 7.
• Procedural generation of very large, detailed terrains.
• Procedural generation of streams, rivers, lakes and oceans.
• Manual editing of terrain (for placing man-made features)
• Option to add roads
• 64-bit O/S support
• Multi-core CPU support

Does anyone have any suggestions?

Creation of roads and rivers isn't mentioned in the list of features for Terragen 3 and searching for those terms in their forums brings up posts about using third party software to add them to Terragen 2 terrains.