Ray tracing graphics hardware, it’s a research project at a university, so they don’t have real hardware that is all that impressive, but the video that came out of their simulator is awsome.

Hardware Simulator video

And the successor project is here

Yeah, even though I have no intention of any doing 3d graphics programming, I just can’t passup a Carmack presentation. He has a way of talking of which is like a window into a great mind.

That it is his lifes work and he shares unselfishly and publicly makes all the difference. Fascinating to hear him muse on the next experiments he’ll be doing. Out of my depth here but what I took from the talk is that he perceives that uncompressing and accessing the data format is where the logjam is now rather than in the rendering of surfaces. If he solves that he knows he can hack other approaches to render surfaces close enough to any ray traced hardware. And you better believe that rendering gum on a bench is the most banal of possibilities.

The guy working on this is doing voxel-based rendering on the graphics card in real time by creating meshes on the fly and sending them to the GPU. According to him, he uses similar methods to generate geometry for the GPU at his job, where he works on medical visualization software.

“I have no idea what makes it ’sparse’ though.”

A sparse octree only divides its octants up where there is actually something to represent. You have your 3D space. A non-sparse (dense) octree algorithm would divide this space up into octants, and each of those up into 8 until you reach the maxiumum depth. A sparse octree instead only makes this subdivision for areas where things exist – areas with nothing in them don’t get subdivided. It’s a little hard to explain without a diagram.

What we dont seem to agree upon is that photon mapping uses raytracing as part of a wider process that produces results of far higher quality, and as its becoming possibl possible to run photon mapping programs in realtime on gpus it seems a waste of time trying to implement a pure raytracer (which, funnily enough, seems to have nothing to do with carmacks plan).

i dont want to argue on the internet… im hungover

If you use pregenerated photon maps with a non-ray tracing renderer what you are doing at that point isn’t photon mapping, you are basically just rendering using precomputed light information.

Your example of the physics engine is way off, most physics engines do not use any form of ray tracing, they use various forms of volume collision checks. The point being you can implement a physics engine completely without using ray tracing but you cannot implement photon mapping without having a ray tracing engine. You may have created a photon map like affect but it was not photon mapping.

http://ioquake3.org/2008/03/04/raytracing-ioquake3/

As you can see, it’s neat but nothing mind-blowing in the visual department, simply because it’s rendering content (map geometry and textures) that wasn’t designed to take advantage of it.

Others here have summarized the approach Carmack is researching, but the key phrase is really “unique world detail”. The megatexture stuff in current gen lets artists paint unique detail on any part of a huge world, so extending that to geometry, an artist can decide to put a wad of chewing gum on the underside of one specific bench in a park, and the engine can handle that from 10000 feet with minimal overdraw or running out of memory.

Also, those nasty sharp-edged shadows we can’t seem to escape this generation would probably go away, without the expensive multisampling approaches we have to settle for now.

From my perspective it all sounds like we’re getting seriously close to the point of near-total diminishing returns, but Carmack has made 3D graphics the Problem to Solve for his career, and his pursuit of that has been very respectable (even if it doesn’t always produce GotY).

I empathise. When triangle size gets less than one pixel around here, it’s complete chaos. Jim starts screaming, Walker just flakes out completely and it’s only Alec who keeps his head together, reassuring us that triangle size will be back at more than a pixel shortly.

Damnit, don’t make me laugh, I’m in a library.

Oh, and storage (i.e. Hard Drive) technology has to undergo a major shift to make accessing all this data fast enough possible.

I remember playing the outcast demo and thinking “where’s my voxel accelerator card?!?” Somebody mentioned something about voxels and 3d cards, but I don’t think any voxel-based game released ever used 3D acceleration of any kind.

The real question is – once we get through all that, will we then get more power allocated for simulating more interesting things, like A.I.? How about real AI characters, not just better pathfinding? (Thought that’s greatly needed too!)

‘Photon mapping is raytracing’ is as true as saying ‘Physics processing is raytracing’

True, photon mapping traces rays, but so does goldsource! Its mearly a stage in the mapping process. Photon mapping is not ‘defined by’ raytracing at all – it borrows more from radiosity if anything.

After writing a hashed-based photon mapper intended for use on the GPU for my degree, I like to think ive got a bit of a grasp on the subject, although i may have been a bit too scathing on RT – its in my nature :P