quote:Original post by cliffhawkens
Well, saying "voxel landscapes can only be rotated around the y-axis" doesn't mean that...but then again, I can't take every article for the Gospel truth, now can I? Of course you're right (Delta Force), but I'm just wondering how it's done....

Ok. I just scanned through the flipcode tutorial and you may be right. I assumed that rotating about the X axis would be ok for that algorithm but maybe not. I'm not really bothered to work out why not.

Outcast and delta force may not use the raycasting technique though. The constraint to 4 degrees of freedom is only a side-effect of the raycasting technique.

If you want to make an engine just pick a technique an go for it. Raycasting is nice for people who prefer simple co-ordinate geometry to matrix math (Like me). I think you've got alot to go on with just that flipcode article.

Otherwise just try your nearest search engine for other techniques.

ro


Edited by - rowbot on January 17, 2001 7:08:42 AM

With a standard "voxel" heightmap engine columns have to map to straight lines on the heightmap AFAICS. And thats only true if you look straight ahead, you can do some tricks by shifting the columns/up down or doing tilt as a post processing step. But basically with that kind of method you only have 4 DOF.

In the general case (6DOF) however the mapping of straight lines on the screen to straight lines of the heightmap still hold. Unfortunately they extend from the epipole''s outward on the screen and the heightmap, so no more nice colums in the general case... those are just a limit case.

Check:
http://mania.snu.ac.kr/~chlee/JVCA.ps
(on his homepage it said they were considering extending the technique to RLE encoded voxel sets, the difference between voxel&heightmap rendering isnt that great after all, but nothing came of it AFAICS)
And
http://www.graphics.lcs.mit.edu/~gs/papers/dispmap/
(this explains the relation to IBR and epipolar lines a little better, but in the context of more general displacement mapping instead of just a heightmap)