Global Illumination: (56k modem warning)

["Nerve-Damage"]

1. What current and future game titles from the PC, Xbox 360, and PS3 will contain or feature real-time Global Illumination?

2. Which platform will provide the best performance for real-time Global Illumination (why and how)?

Some detail factual based opinions will do!! :smile:

Background:

Global illumination: algorithms used in 3D computer graphics are those which, when determining the light falling on a surface, take into account not only the light which has taken a path directly from a light source (direct illumination), but also light which has undergone reflection from other surfaces in the world (indirect illumination).

Images rendered using global illumination algorithms are more photorealistic than images rendered using local illumination algorithms. However, they are also much slower and more computationally expensive. A common approach is to compute the global illumination of a scene and store that information with the geometry (ie. radiosity). That stored data can then be used to generate images from different viewpoints for generating walkthroughs of a scene without having to go through expensive lighting calculations.

Radiosity, ray tracing, beam tracing, cone tracing, Path Tracing, metropolis light transport and photon mapping are examples of algorithms used in global illumination, some of which may be used together.

Examples (V-Ray Technology):

 

[Dr. Nick]

I would like to know as well. Even though whats his name, the guy in charge of Blue Dragon, said that were using it I doubt he was talking about the same thing in the info given above.

 

[mckmas8808]

WOW that looks great. To bad we won't be getting that next-gen.

 

[AlNom]

if we get GI, we won't get a lot of other things at the same time in this upcoming gen.

 

[scificube]

Given many of the discussions I've observed here it would seem any real hope of using ray-tracing for anyting is misplaced...at least for the current generation (when is next gen this gen anyway?). From what I've seen the best we should hope for is some sort of ambient occlusion approximation and/or radiosity baked into textures. That's what I gather anyway.

 

[Dr. Nick]

Given many of the discussion I've observed here it would seem any real hope of using ray-tracing for anyting is misplaced...at least for the current generation (when is next gen this gen anyway?). From what I've seen the best we should hope for is some sort of ambient occlusion approximation and/or radiosity baked into textures. That's what I gather anyway.

Yeah, sorry that is what he(the developer at mistwalker) was talking about Global Illumination Approximation. Sorry.

 

[scificube]

Yeah, sorry that is what he(the developer at mistwalker) was talking about Global Illumination Approximation. Sorry.

No need to apologize. Any developer insight is good insight and intelligent discussion is equally always good.

I still lost as to what you're apologizing for in the first place given your first post in this discussion

You're too nice dude...you need to get off the internet before it pollutes you.

 

[Confidence-Man]

nm. didn't read.

 

["Nerve-Damage"]

Crash Course:

Crash Course:

 

[Sonic]

Yes, it most likely will not happen in real time with the new systems. That doesn't mean that as devs get more intimate with the new console hardware they won't be able to fake it to a rather good level.

 

[scificube]

Crash Course:

There's some nice work going on here! Thanks for the info.

 

["Nerve-Damage"]

Games that I found (or rumored) to be using some form of Global Illumination

* Dog Tag (PS3, Xbox 360, PC): Global Illumination Light Mapping

Proprietary game engine with full environmental and player collision physics, dynamic shadowing and global illumination light mapping

* Hellgate: London (PC): Global Illumination

Global illumination is the task of representing light coming from and interacting with the environment. In this case, the moonlight is casting light onto the scene and causing shadows to appear on the moonlit streets and buildings. The sky is at times an ominous dark green color and other times a dull glowing red. At least some light should be bouncing back from the ground and walls, back-lighting the characters and other objects.

Getting that lighting to show up in the world in an efficient, real-time way is the task at hand. There are quite a few ways to attack the problem. The common approach has been to use so-called "lightmap" textures to apply pre-computed global lighting to all the fixed, non-moving objects in the world. A newer technique is to create a series of functions to describe the incoming light from various directions and then compute and store the correct lighting values for the functions all over the world to be reconstituted into actual light data at runtime. (Whew.) The most expensive approach would be to actually calculate full lighting and shadowing at runtime in shaders for every single pixel on the screen. Hybrid approaches are common: a major game in recent history used three lightmaps to store lighting values for three approximation functions.

* Blue Dragon (Xbox 360): Global Illumination Approximation

"We originally used something similar to Cell Shading," Sakaguchi discloses, "but we ended up with this [style] -- minus outlines." The Blue Dragon characters and visuals do indeed look like they're using a different rending technique than what's commonly referred to cell shading, as objects don't have black outlines. In other interviews, Sakaguchi has referred to the game's visual style as being akin to Clay Animation, with lighting that approaches an advanced global illumination lighting model, which, more realistically, takes into account light from throughout the world rather than light exclusively from light sources.

 

[DudeMiester]

No game will be using real time global illumination, it's just WAY too slow. However, many games will pre-compute GI and store the results via lightmaps, SH, etc...

btw, if you want to see really good GI effects (way beyond your pics) take a look at www.maxwellrender.com . Their unique feature is that they don't use RGB to store colour, but rather a full HDR FFT of it (in other words, a large frequency spectrum). It makes for mind-blowing results that take absolutely AGES to render!

 

[mckmas8808]

No game will be using real time global illumination, it's just WAY too slow. However, many games will pre-compute GI and store the results via lightmaps, SH, etc...

What is the quality difference between real GI and this pre-computed GI? Is this fake a good fake? Or is it obvious at first sight that it's not even close to the real time?

 

[overclocked]

I guess for performance reasons that "true" GI wont happen but there are already various implementions that i think we will se combined. Personally i like the cubemap approach with different light sources. I think there some demos out there that shows this quite well, nVidia did one demo im pretty sure but havent read the exact implemention of it but the end-result was quite staggering.

There was one papper that had a good approach with a shader doing fake/fast GI, Stanford i belive.

 

[MrWibble]

What is the quality difference between real GI and this pre-computed GI? Is this fake a good fake? Or is it obvious at first sight that it's not even close to the real time?

It depends what has been precomputed and how it gets turned back into a basic lighting value at run-time.

Generally what is lost is the ability to move things around freely and have the lighting result update correctly. So for a static scene it'll work very well, but for something moving around (or that has large things moving around within it - like a player and some bad guys for example) then it'll start to fail.

You would usually want some kind of half-way house, storing information about how light moves around the scene but not the lighting values themselves. Essentially you store as little as possible while still leaving the ability to quickly calculate a lighting value at runtime.

In more specific cases you'll have other issues. If using something like spherical harmonics to encode the light transport, you will quite often lose high-frequency lighting effects (sharp edges to shadows, which do occur naturally sometimes). Or alternatively the lighting might lose resolution or start to alias, just as with any other non-per-pixel thing.

 

[davepermen]

precomputed vs. realtime gi is not a quality issue, it's an issue of static vs. dynamic.

it's like if doom3 would not have any dynamic lights and shadows.

realtime gi would give you, that you could place a fire into a room, and walk over to the other room, wich gets then illuminated by the fire of the other room, and you see the red-yellow flickering all over the walls.

realtime gi means the same as what the realtime direct illumination in doom3 ment, just for gi effects.

http://graphics.ucsd.edu/~henrik/animations/jensen-the_light_of_mies_small.avi this video shows an animation of the sun both with just direct illumination (doom3), and full gi.

this could not be done with precomputed gi lightmaps (okay, you can precalc _ANYTHING_. but think of being able to move the sun however you want.. and the building-components. open, close doors, move the table, etc.. if you want all the dynamics you can have today with the physics, you want your lightingsystem to react to it. precalculated stuff can't.

realtime gi is a great thing to play with. even while it's too slow in general terms, it gives a great impression.

 

[davepermen]

should have posted the link to the page i've got the video from, too..

http://graphics.ucsd.edu/~henrik/animations/ there are all sort of animations. publications, etc.. the book is great, too.

on http://realstorm.com/ you can see this movie, a demo on their realtime software raytracing work: http://www.realstorm.com/realstorm/data/RealStorm_GI_Bench_2005_Preview.avi wich shows lowquality, but at least interactive GI. the topdownview looks quite good and gives some idea on what could come one day..

 

[Danalys]

No game will be using real time global illumination, it's just WAY too slow. However, many games will pre-compute GI and store the results via lightmaps, SH, etc...

btw, if you want to see really good GI effects (way beyond your pics) take a look at www.maxwellrender.com . Their unique feature is that they don't use RGB to store colour, but rather a full HDR FFT of it (in other words, a large frequency spectrum). It makes for mind-blowing results that take absolutely AGES to render!

thanks for the link. i love stuff like this. looks like we may have got true photorealism finally. now onto finding an aproximation that can run real time.

 

[MrWibble]

precomputed vs. realtime gi is not a quality issue, it's an issue of static vs. dynamic.

it's like if doom3 would not have any dynamic lights and shadows.

In many precomputed illumination schemes having lighting dynamically changing is not nearly as much of a problem as having the objects or geometry itself change.

If I had an outdoor scene only lit by the sun, I think I could quite easily generate a lightiing model that closely approximated the GI result, but let me change the time of day arbitrarily. However if I wanted a moon to move in front of the sun and cause an eclipse, that would be a problem.