I've been meaning to post something technically meaningful for a while now. As you might have noticed, my recent journal entries have basically been of a quality somewhere around the Lounge [grin]

I love terrain rendering, I've written at least 10 partial terrain engines. Usually each practiced a particular technique (e.g. texturing, shadowing, culling etc..) I also like to post my thoughts on the numerous threads that pop up about it in the forums.

My current work means I have no time to write code "for the hell of it" atm ([sad]), so I'll resort to thinking about writing it instead.

Anyway, I see terrain graphics in 3 parts

1. Geometry contruction

Things like heightmapping, (ir)regular grids, parametric surfaces etc...

2. Landscape texturing

How the terrain appears, things like the grass/rocks/dirt/snow distribution

3. World/scene lighting

Things like the sunlight, local lighting, shadows, per-pixel lighting etc...

I'm thinking that I'll cover my thoughts on these and-and-when. I've got loads of notes written up from the last few years, loads of printed articles (and saved digital ones) to read over.

Inspired by something someone posted on the forums recently, I've been thinking that dual heightmaps might rock in a big way.

I like regular height-maps a lot; they're dead easy to implement, dead easy to manipulate (for creating a landscape) and they fit a lot of very CPU/GPU friendly algorithms (good for performance etc..)

However, they aren't the best for artistic expression - no overhangs, no caves etc..

So, if we create a low-resolution heightmap (say 100x100) that just defines the general shape of the world. Then, for each quad that exists in the terrain, we apply a second heightmap that can have either positive or negative values.

This second heightmap is of a higher resolution (thus, giving us an overall good resolution).

This heightmap is offset based on the plane that the current quad creates; thus if the general shape of the world is a cliff/steep-slope you could create minor caves and overhangs.

There are still a few issues with this approach that I'm contemplating, but I think it could go a long way to being a good solution that's also friendly to the system it runs on (and the programmer writing the impl).

Anyone seen anything like this before?


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