Some of you may have heard this story floating around. Basically, some tiny Australian startup claims to have created a method to display models in unlimited detail in massive quantities quickly and efficiently. Yeah, pretty much what it sounds like. No it's not a bunch of ray casting, it's representing the entire world as many, many points. A supposedly revolutionary technique which allows the efficient application of this "point cloud" is explained by this video:
http://www.youtube.com/watch?v=Q-ATtrImCx4For those of you less knowledgeable about 3D graphics, all the big words sound awfully convincing. For those of you well versed in graphics programming, it sounds like a steaming pile of bullstuff. Well, you're sort of right either way. To an extent, they are telling the truth. They DO have the ability to render things in high resolution with high efficiency. The downside? It's already been known about for quite a while.
Enter sparse voxel octrees. For a simple explanation, just imagine a 3d model of, say, Trololo with an invisible box surrounding him. The box contains information about the material it contains. To make Trololo more detailed, you split the box into 8 smaller ones and repeat until the correct amount of detail is reached. The SPARSE voxel octree cleverly makes sure to only keep data regarding the outside of a model, ensuring that most of the octree is empty. This reduces memory used, and, in turn, time spent searching through it.
The sad thing is, these are almost impossible to animate. Notice that nothing in the video is moving, only looked at from different angles. Building octrees takes forever, and forget about doing ragdoll animation with it. I suppose maybe preset sequences could implement them, but any on-the-fly octree building is out of the question, at least for now.
John Carmack (Yeah, the genius behind Doom, Quake, Wolfenstein, etc.) has a nice discussion about rendering techniques, including sparse voxel octrees, here:
http://www.pcper.com/article.php?aid=532For more technical info, here's a great paper about it:
http://lefebvre.sylvain.free.fr/octreetex/octree_textures_on_the_gpu.pdfOpensource library for using sparse voxel octrees:
http://code.google.com/p/efficient-sparse-voxel-octrees/
