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Carmack Speaks On Ray Tracing, Future id Engines
Vigile writes "As a matter of principle, when legendary game programmer John Carmack speaks, the entire industry listens. In a recent interview he comments on a multitude of topics starting with information about Intel, their ray tracing research and upcoming Larrabee GPU. Carmack seems to think that Intel's direction using traditional ray tracing methods is not going to work and instead theorizes that using ray casting to traverse a new data structure he is developing is the best course of action. The 'sparse voxel octree' that Carmack discusses would allow for 'unique geometry down to the equivalent of the texel across everything.' He goes on to discuss other topics like the hardware necessary to efficiently process his new data structure, translation to consoles, multi-GPU PC gaming and even the world of hardware physics."
John Carmack == Commander Keen == id Software == Doom = Wolfenstein == Quake == ??
You've never heard of any of those? the guys you mention might not even be in gaming if it weren't for Carmack and John Romero.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
Bog standard ray tracing, which is what intel are harping on about at the moment isn't the be all and end all of global illumination algorithms, as many people who get all misty eyed about the technique would have you believe. It's terrible for diffuse interactions for one thing. Photon mapping is a more realistic technique which simulates light more accurately.
Tim.
Funny. It's just freaking amazing that someone would even stoop so low as to mention Gabe Newell and not know Carmack. Hell, the original Half-Life is written on the Quake engine written by Carmack.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
"Ray tracing" traditionally means specifically tracing rays from the eye out into the scene. Other methods are usually referred to by different names.
And even so, while tracing either photons or eye rays may be the most feasible method at the moment, it is by no mean the only way to solve the rendering equation, nor any kind of theoretical best.
Except the double-slit experiment. It's based on the fact that light has wavefront qualities, while ray tracing treats it as particles.
I also strongly doubt that the discreet ray approach will ever produce very good global illumination, since the number of rays bouncing between surfaces quickly grows towards infinite as the desired accuracy grows.
You'd need to do "wavefront racing" to fix these, and I for one have no idea how to do this - solve the quantum field equations for each particle in the scene after inventing the Grand Unified Theory ?-)
Forget magic. Any technology distinguishable from divine power is insufficiently advanced.
As far is I've understood it he isn't exactly using the octree for LOD but for storing all voxel data in s parse (there we have it ;) manner. If you only have one "layer" of voxels at whatever resolution defining eg. only the surface of things, most nodes of the octree will remain empty, and so you can reduce the data set to storing only what's necessary for rendering instead of having to store a full-resolution 3D representation of your space.
Of course this leans happily towards a LOD system, as storing the data in different resolutions aka mip-mapping the geometry and then accessing the right detail level would essentially be for free if you do it right.
In the end it's a promising approach with of course many details to be sorted out - there's still a lot of data to be stored per-voxel (texture coordinates, normals, basically everything that now goes into a vertex) if you want the full feature set like eg. lighting and such. But given dedicated hardware and combined with his mega texture stuff (which is basically only glorified unique UV mapping, perhaps somewhat generalized and with a good resource management system behind it) this could be pretty cool.
In our current generation codebase we have moved to completely separate representations for rendering and physics, and I expect that to continue in the future. The requirements are different enough to merit different internal storage.
John Carmack
Tracing into an SVO structure can be done with almost a Bresenham algorithm, and when you reach whatever depth of descent you want (a critical factor, you aren't going all the way to final detail on every trace), you pop out whatever data is stored there (probably some vector quantized BRDF sort of thingy) and run a "fragment program" on it.
The data sets for a game world represented like this would be massive, but it is intrinsically well suited for streaming, even over the internet, which may well be the dominant media distribution channel in the timeframe we are looking at.
John Carmack