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irreversible

Complex fractal terrain

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irreversible    2862
I can't find almost any information on non-trivial fractal terrain and its texturing. Complex terrain includes overhangs, caves, coves and other elements that have a true 3D nature (where the surface of the terrain folds back on itself), but also such elements as steep natural-looking cliffs in an otherwise smooth environment. I'm pretty sure a lot of research has gone into this. In fact, purely by viewing some of the stuff from Terragen 2, such as this is proof of that. I just can't find any good information on it on Google. And I'm also assuming voxel terrains aren't the answer. Does anyone have more experience with this? I would much appreciate a link or two to get me started.

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Guest Anonymous Poster   
Guest Anonymous Poster
Best one I ever saw (but I don't think it had overhangs or caves) the guy basically created a 'fractal scripting' lanaguage. Where he had a series of operations that allow the mixing of different fractals -add, multiply, mask, etc
and basically, he starts at a Global plantary level -an ocean/vs/land fractal map
and works down in levels all the way down do rocks more or less...
land->hills/valleys->environments->etc...
So it was pretty heirarchial

I'm afraid I dont remember Who or What the name was... If anyone recognizes it, pls share.


Ant any rate, the bottom line was that a Single perlin noise type of deal is Not adequate complexity, you need to combine different fractals..., and use other fractals to decide the combination weightings, where each of those in turn is yet another combo of different fractals, etc...

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irreversible    2862
I've been working on terrain generation myself based on the Musgrave book - and that's slowly coming along - I'm starting to get a variety of different results in real-time.

Additional research, however, has turned up only one term to describe overhangs and outcroppings: "procedural displacement". Googling this will produce a lot of results, but not so many apparent descriptions on how to apply horizontal displacement to a polygonalized terrain.

I have an idea in my head how this would work, but I feel like reinventing the wheel with huge potential for going wrong.

My idea of this involves taking the slope of a certain angle - then, if it's steep enough -, tessellating (subdividing it) and applying a fractal displacement along the average normal of the slope. This also sounds quite expensive, since I'm aiming for real-time.

AP: what you described is described in more detail in this paper; although this does not include overhangs - just a complexification of the terrain by combining different noise structures.

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