Question about tech demo

[Simon82]

Hi,
I'd like to know why there are no tech demo or example of what could it really be an ambient with realistic illumination. I ask this because I see too many examples of extremely complex ambients with millions of polygons, ultra detailed textures, powerful shading effects but not a internal point of view of a simple box with a simple window with a realistic global illumination, hdr, radiosity, raytracing and any sort of illumination effect that could make me think "OK! this is realistic!" and this is what I can do with 3DStudioMAX starting from a grey empty layout.

Bye

 

[alt_nick]

Something like the Cornell Box?
It's pretty much the standard for offline renderers.

I'm guessing you've mostly been watching the fancy tech demos from Nvidia, ATI and game companies?
The demos that demonstrate actual new (implementations, not theoritical) techniques at opengl.org, humus site and whatnot rarely use elaborate surroundings as they're done by programmers and not teams with artists.

You rarely see the best stuff unless you are 'in the scene' (like us oldtimers used to say before youngsters defiled it )

 

[Nick]

I'd like to know why there are no tech demo or example of what could it really be an ambient with realistic illumination. I ask this because I see too many examples of extremely complex ambients with millions of polygons, ultra detailed textures, powerful shading effects but not a internal point of view of a simple box with a simple window with a realistic global illumination, hdr, radiosity, raytracing and any sort of illumination effect that could make me think "OK! this is realistic!" and this is what I can do with 3DStudioMAX starting from a grey empty layout.

That's because rendering millions of polygons is only an O problem, i.e. the the computational power you need is linear with the scene complexity. Make hardware two times faster and you can double the number of polygons.

Global illumination has O(n^2) complexity, since every polygon affects the lighting on every other polygon. So you can only render a thousand polygons compared to the million for the O rendering. Double the hardware's performance and you can only render 40% more.

I simplified the whole process, but it's really the algorithmic complexity that makes it so hard to do unrestricted realistic lighting. With some hacks and heuristics it's possible to get satisfying results though. But we're still some years away from widely using it in real-time applications.

 

[Simon82]

That's because rendering millions of polygons is only an O problem, i.e. the the computational power you need is linear with the scene complexity. Make hardware two times faster and you can double the number of polygons.

Global illumination has O(n^2) complexity, since every polygon affects the lighting on every other polygon. So you can only render a thousand polygons compared to the million for the O rendering. Double the hardware's performance and you can only render 40% more.

I simplified the whole process, but it's really the algorithmic complexity that makes it so hard to do unrestricted realistic lighting. With some hacks and heuristics it's possible to get satisfying results though. But we're still some years away from widely using it in real-time applications.

Thanks for both answers. Do you think that actual GPU shading power, general purpose computational one and processor quad core could not solve a cornel box like the one below?

 

[ector]

Thanks for both answers. Do you think that actual GPU shading power, general purpose computational one and processor quad core could not solve a cornel box like the one below?

I don't see your cornell box, but of course it can solve it in realtime, it's just a matter of choosing the right hacks. But for general scenes with reasonable complexity? No way. If it was possible, why is your 3DS Max render taking minutes?

 

[Simon82]

I don't see your cornell box, but of course it can solve it in realtime, it's just a matter of choosing the right hacks. But for general scenes with reasonable complexity? No way. If it was possible, why is your 3DS Max render taking minutes?

Yeah, but like it was told in other threads, it's something about the arts of the develoapers. Take GT4 for example on PS2, take Half Life 2 on PC. There're point of view in some areas that give realistic rendering with so many tricks, I know, but always realistic.
I think that Prison area in HL2 give the right idea of what many coders and artists could search on their game. Moderate use of the useful effect and not every to the maximun range so that these are visible to the customers.

 

[Albuquerque]

Yeah, but like it was told in other threads, it's something about the arts of the develoapers. Take GT4 for example on PS2, take Half Life 2 on PC. There're point of view in some areas that give realistic rendering with so many tricks, I know, but always realistic.
I think that Prison area in HL2 give the right idea of what many coders and artists could search on their game. Moderate use of the useful effect and not every to the maximun range so that these are visible to the customers.

Yes, but the game examples you gave (GT4 and HL2) have "prebaked" lighting -- meaning they really aren't computing the lighting effects in real time. What you're asking for is wildly different than what those two games are giving you.

 

[Simon82]

Yes, but the game examples you gave (GT4 and HL2) have "prebaked" lighting -- meaning they really aren't computing the lighting effects in real time. What you're asking for is wildly different than what those two games are giving you.

But they let you imagine a realistic environment.. maybye if all the computing power could be balanced with this tricks, ,we could have more realistic game since years ago. Far Cry was the example that being an excellent title with all the latest supported features, it didn't reach nothing of barely realistic, starting from the "oil painting effect"..

 

[Albuquerque]

But they let you imagine a realistic environment.. maybye if all the computing power could be balanced with this tricks, ,we could have more realistic game since years ago. Far Cry was the example that being an excellent title with all the latest supported features, it didn't reach nothing of barely realistic, starting from the "oil painting effect"..

I don't think HL2 reached anything of barely realistic -- when was the last time a cracked wall was actually completely and utterly flat (to include the crack?) Or a brick wall completely and utterly smooth? Or a tiled floor? Or a wooden floor? I could go on for eons.

You're too busy looking at the textures to look at the rest of the graphics. If all you want is realistic texturing, then take a few very high quality snapshots of a room and carefully apply them to a cube in your favorite engine. Get them lined up right and you have a "realistic" room. There's HL2.

Now if you want the light to change as you walk around, or if you want your carpet to truly appear fuzzy, or want your bed sheets to truly appear wrinkled (etc) then you need something else. Same thing goes for how the light reacts to all these surfaces (subsurface scattering, radiosity / spherical harmonics, etc) and how the shadows behave as objects move closer to or further away from a light source (penumbra, volume shadows, perspective correct on various planes, etc)

There's a lot of things you're completely glossing over when you're saying that all that lighting, shadowing and "bumping" technology really isn't necessary.