Raytracing discussion

[Cogman]

I thought this might be fun.

What are your thoughts one raytracing. Do you think that it will ever replace rasterization as the 3d rendering mode of choice? Or is it more of a pipe dream.


For me, certainly the benefits are clear. Everything that is hard with rasterization is made easy with ray tracing. You don't have to worry about shadows, reflections, or moving lights. They pretty much naturally follow from it.

Not only that, but it is the perfect match with the direction that PCs are heading. The push for more and more CPU cores and more general purpose GPGPUs is leading to an environment where rasterization may be shoved into the back as the ugly stepchild that nobody wants to remember.

The issues, however, as I see it come in two forms. The first is the fact that a standard raytracing library really doesn't exist. As such, hardware optimizations, etc, are a long way away. You'll pretty much end up writing your own raytracing library if you want to get things done.

The next is the fact that raytracing isn't a silver bullet. Things often look plasticy as a result of raytracing (See: just about every 3d animated movie). This may be a good thing if you want to make things look like a cartoon, bad if you actually want realism.

I, personally, think that it will most likely be the future of 3d rendering. The hardware is going that direction, it is only natural that the software would follow. Once someone develops a standard raytracing library, we will start to see raytracing games on the market.

The fact that there are several programs that use it for rendering is only the beginning.

 

[dinkumthinkum]

Funny, I was just talking about this yesterday. There is already efforts at real-time raytracing, just google up nvidia's efforts.

As for "plastic-y" that's really just a function of how good a job you do. You can find plenty of examples of ray-traced scenes that you simply would not believe were rendered, if you weren't informed.

So yes, I think it is the future

 

[wuliheron]

AMD is promoting the production of the first ray traced Anime feature film that will use the exact same graphics in a video game. It won't be anything like the ultra realistic ray traced photos, but its a start. One racing game either already out or coming out also uses ray tracing to produce life-like images of the cars you can choose from.

However, it will likely be another twenty years before ultra realistic real time ray tracing on a desktop becomes possible and long after that before the technology becomes mature. In the meantime I'd expect to see more movie special effects use the technology since they don't require the frames to be produced in real time.

 

[Cogman]

AMD is promoting the production of the first ray traced Anime feature film that will use the exact same graphics in a video game. It won't be anything like the ultra realistic ray traced photos, but its a start. One racing game either already out or coming out also uses ray tracing to produce life-like images of the cars you can choose from.

However, it will likely be another twenty years before ultra realistic real time ray tracing on a desktop becomes possible and long after that before the technology becomes mature. In the meantime I'd expect to see more movie special effects use the technology since they don't require the frames to be produced in real time.

Movie makers have been using ray-tracing for years. Toy story, for example, is ray traced.

The thing is, with ray-tracing detail doesn't really determine performance. So long as you have the memory to store the detail, you can render it.

 

[Markbnj]

Movie makers have been using ray-tracing for years. Toy story, for example, is ray traced.

The thing is, with ray-tracing detail doesn't really determine performance. So long as you have the memory to store the detail, you can render it.

And it still takes a ton of hardware it get those results in a reasonable time.

http://www.slashfilm.com/cool-stuff-a-look-at-pixar-and-lucasfilms-renderfarms/

 

[degibson]

Whether raytracing becomes mainstream or not will depend only on someone building a single package that can raytrace 1680x1050@30fps. Whether that's a GPU, CPU, ?PU, ASIC, hardly matters.

Given the power, thermal, and scaling obstacles on the horizon, I'm a skeptic.

 

[mikelturner]

I would think it would be far off, at least, before ray tracing becomes heavily used in anything real-time like games. Many of the techniques that are used for speeding up ray tracing can be used with the current rasterization techniques that provide more bang for the buck.

 

[Cogman]

I would think it would be far off, at least, before ray tracing becomes heavily used in anything real-time like games. Many of the techniques that are used for speeding up ray tracing can be used with the current rasterization techniques that provide more bang for the buck.

I don't see how the two are compatible. I mean, they are fundamentally two different ways of doing things. Raytracing itself is really quite a simple algorithm, I don't really see where the speedup techniques for it would apply to rasterization.

If you could explain or even give examples of where the two have mixed, that would be amazing.

 

[Markbnj]

I don't see how the two are compatible. I mean, they are fundamentally two different ways of doing things. Raytracing itself is really quite a simple algorithm, I don't really see where the speedup techniques for it would apply to rasterization.

If you could explain or even give examples of where the two have mixed, that would be amazing.

I might argue that raycasting was a mix of raytracing and rasterization, just to be pedantic.

 

[GodlessAstronomer]

Binary Space Partitioning is an example of a technique that can be used to optimize ray tracing and rasterization. They are used in different ways, but it's an example

There are certain things that are common between ray tracing and rasterization. Texture mapping, bump mapping, mipmapping, intersection algorithms, partitioning algorithms, lighting calculations, computational geometry (primitives, constructive solid geometry, etc) are all things that apply to both rasterized and ray traced scenes. Anti aliasing techniques are also shared somewhat. No to mention all of the ray casting that actually happens during a game - not necessarily for rendering, but in physics calculations, hitscan weapons, etc.

I'm sure some people could give you more concrete examples, my experience with rasterized graphics is limited.

 

[CU]

I think one thing that raytracing adds that rasterization can't have is precise shapes which are defined by a formula like a sphere instead of approximations like n-polygons forming an approximation of a sphere. This along with how reflections, shadows, etc. are handled in raytracing will lead to it being the rendering choice of the future. Eventually hardware will not be the limit, so added features and easy of use will win out. Then we can shoot for radiosity for global illumination.

 

[GodlessAstronomer]

It's a common fallacy that ray tracing always leads to the most realistic lighting conditions automatically, just by virtue of it being ray traced. The truth is somewhere in the middle. Because most ray tracing is actually reverse ray tracing, where we trace from the eye to the intersection points (as opposed to forward ray tracing, where we trace photons from their origin to the eye) we can't actually simulate some real effects such as light bloom. Some of these effects are nearly trivial for rasterized engine - just look at modern games like Bad Company 2 or Crysis 2.

Some people believe that real-time ray tracing is not far away. I'm undecided on that, but one thing I know for certain - we will not see real-time forward ray tracing for a long time, maybe not even in our lifetimes. It is far more computationally intensive.

 

[CU]

True forward raytracing would be better. But that is a further off than reverse. Although I would think some optimizations and specialized hardware for reverse could work for forward.

 

[KIAman]

How about double ray tracing? A sort of ray tracing anti-aliasing where you trace a ray/vector from the eye up to the point of the maximum defined reflections allowed, detect if the surface is giving off light, then ray trace back to the eye.

Steps.
1. Trace from eye to surface
2. Reflect to defined maximum allowed reflection
3. Detect if end surface is giving off light or light source
4. Trace back through all reflections back to the eye while correcting each point of intersection with new data

The hardware resources required would be pretty astronomical considering you would need to allow close to infinite allowed reflections AND doubling each ray trace path.

Also, ray traced images CAN be photo-realistic. It is all in the surface properties, number of reflections/refractions/absorptions allowed of what you are rendering that determines the "plasticy" look or not.

 

[mikelturner]

I don't see how the two are compatible. I mean, they are fundamentally two different ways of doing things. Raytracing itself is really quite a simple algorithm, I don't really see where the speedup techniques for it would apply to rasterization.

If you could explain or even give examples of where the two have mixed, that would be amazing.

I won't be much more help than GodlessAstronomer since I was thinking along the same lines as him with acceleration structures in general. Like kd-tree (I know a special case of BSP), the mentioned BSP, oct trees, bounding volume heirarchy, etc.

At least I think all of this was applicable to both, it's been 10+ years since I've done with graphics (and only for a limited time then). So, really I should have kept my mouth shut because 1)my memory may be faulty and 2)I'm not up to date on anything. Oh, well.

 

[Sureshot324]

Ray tracing is so drastically more computationally complex than rasterization that I believe it will always be a case of 'we could make a ray traced game with level of detail of 15 year old games, or we could just use rasterization'. Just recently someone made quake 3 using ray tracing that runs at barely playable framerates on modern hardware. In 10-15 years someone will probably do the same for Crysis 2, but it will still look like shit compared to the games of that time.

 

[Kaido]

I wrote a game engine based on POVray about 10 years ago. It ran at 1 frame every 3 seconds on low quality at 320x240 resolution. But dang if it didn't look good :awe:

 

[wwswimming]

it kind of depends on who is paying the power bill to run the computers that are doing the ray-tracing.

if you were a manager in Visual Effects or another user of ray-tracing - then it's your call.

today - it's a lot of kW-hours for a little eye candy.

yes, ray-tracing does look cool.

 

[rogerdv]

The question is if rasterization has a limit, and if that limit is below raytracing limit. If not, then we will keep adding hardware to speed up rasterization, and CryTek will keep making rasterization engines that requires even more hardware, and so on.

 

[Net]

I've come across a few raytracing examples as I'm learning OpenCL. Google "opencl raytracing", it might be interesting to you.