Students Evaluate Ray Tracing From Developers' Side

Vigile writes "Much has been said about ray tracing for gaming in recent weeks: luminaries like John Carmack, Cevat Yerli and NVIDIA's David Kirk have already placed their flags in the ground but what about developers that have actually worked on fully ray traced games? PC Perspective discusses the benefits and problems in art creation, programming and design on a ray traced game engine with a group of students working on two separate projects. These are not AAA-class titles but they do offer some great insights for anyone considering the ray tracing and rasterization debate."

Comments

Re:What's the point ...

[ZiakII]

I know this may not be a popular question, but what is the point with raytracing for games? We're finally getting to a level of technology with rasterization where we're producing visuals at a level which is "Good Enough" (or better) for practically every genre. Do we really need to get on the hardware treadmill for the next 10 years to get to a similar technology level to get slightly more realistic lighting and reflections?

Yes, we do because everything that we do currently is just a hackish like system where we are using programing tricks and other methods to get it to look realistic. Instead of a video card you would just need a faster cpu, which if we base off of moore's law won't be much longer.

Debate?

[Vectronic]

"...ray tracing and rasterization debate"

I don't think there is any debate at all, RayTracing is by far superior, there is just the problem of computing power.

Anyone (perhaps ask the modelers for the games) who deals with 3D software, knows the benefits of RayTracing for simulating reality (Reflections, Ambient Occlusion, Sub-Surface Scattering, etc)

And once computing power reaches that level it will even speed up the process of creating games because you can let the RayTracing take care of shadows, reflections, highlights, etc instead of manually mapping them.

Take a look at anything LightWave, Maya, 3Dsmax, Softimage, Blender, etc spits out of its render engines, or visual effects in recent movies... granted, that's (as stated a few times in the discussion) years away... but, I don't think anyone is arguing against RayTracing.

(-1 Bastard) ...but...whatever, ive been waiting for real-time RayTracing for years even just within my own 3D applications, nevermind games...

Re:Debate?

[Anonymous Coward]

You already have raytracing in games, just not in realtime. Why spend the computing power in realtime raytracing when you can bake the static lighting into PTMs (polynomial texture maps), or the dynamic lighting into spherical harmonics maps, and use these to reconstruct the illumination, including self-shadowing effects, with convincing effects, at a fraction of the cost?
Lightmaps already take into consideration ambient occlusion, check q3map2 for instance, this is nothing new. As for reflections, no one will notice you're using environment mapping, this is specially true if the shaded objects aren't 100% smooth perfect mirror like surfaces - it's a pure waste of processing power.
The only situation where you could see something obvious about raytracing, is in refraction - water, glass, etc...
As for shadows, guess what's the 1st thing someone does when he/she finally has raytraced shadows > looks nice, how can i have blurrier shadows?
And off you go, casting N rays to have basically the same effect you had with multiple shadow maps. This is not to say the existing technology is without faults, only that this raytracing issue seems to have finally caught up with games, and this discussion has been going on for the last +10 years in the traditional CG/VFX area and inevitably the result is always the same > fake the effect, and use raytracing where absolutely necessary.
I don't see why things would be different in games, specially in games, where you have to save whatever processing power you have available, for more important things, such as maintaining a constant minimum fps ;)

Re:What's the point ...

[argent]

Realistic lighting allows you to use those clever algorithms in your head that you've learned over the past 20+ years in the real world, so when you see a flicker of a reflection or a change in the shadows in a darkened tunnel you can turn and blast the damn camper on the opposite rooftop before he nails you with his sniper rifle.

Re:What's the point ...

[argent]

Instead of a video card you would just need a faster cpu, which if we base off of moore's law won't be much longer.

If the video card makers had picked up on the RPU you could use your video card to get realistic high frame-rate raytraced games today.

Dr Slusallek is working at nVidia now, so who knows?

I'd quibble.

[jd]

Raytracing is superior to doing nothing, but conetracing, non-uniform conetracing and wavetracing are all superior to raytracing, and all but wavetracing benefit from adding in radiosity. The advantages of raytracing over all other methods are that it is totally parallelizable and can be implemented using a fairly simple set of algorithms, potentially allowing for a truly gigantic number of compute elements on a single die. One big headache, though, is that to get a significant visual improvement, you have to cast a large number of rays per pixel (or you can't do scatter properly) and you need multiple generations (ie: secondary light sources), where each generation needs to be processed twice - once for direct reflection, once for refraction. This would be fine, but it means different rays will take a different length of time to complete, which in turn means that to get smooth motion, you have to calculate the time for the slowest possible path and synchronize to that.

Typically, however, games manufacturers do NOT mean "raytracing" when they say "raytracing". They mean basic rendering. ie: Applying of shaders and other simple colouring techniques. Renderman, the rendering package used to produce movies like Finding Nemo, uses rendering, not raytracing. Rendering is popular with movie producers because it's fast and "good enough". (Audiences differ on the subject, with plenty of people preferring model-based special-effects because the lighting is real and the reflections are correct - well, they'd better be!) My fear is that true raytracing and physically correct lighting models will be totally overlooked in favour of things that will be cheaper to produce and therefore make more money.

Re:What's the point ...

[Solra Bizna]

The point is that, in raytracing, you can assign each of your 800 "stream processors" different pixels. Done. You're parallel. When one finishes, give it another pixel to work on, and repeat until you've rendered the whole thing.

Each core still has to iterate over all (well, some, I'm oversimplifying) of the triangles, but it can do so COMPLETELY INDEPENDENTLY of the other cores and still come up with a good result. Your performance gains are almost linearly proportional to the number of cores.

You can even have a relatively high-latency connection (Gigabit Ethernet, for instance) between the various cores, broadcast the scene data over this connection, and then receive individual "chunks" of rendered pixels back. I defy you to do that with rasterization.

-:sigma.SB