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DX11 Real-Time Raytracing Tech Demo Running on a i7 + Radeon 5870

Nice jewelry video thanks for the post! It's nice to see a tech demo removed from masculine overtones.

But why does anyone care about this for games? GT4 still looks amazing!
 
It's not IGN bullshit, I remember someone from PD saying in an interview that not only was it using tracing it was also full 1080p (unlike during gameplay where it's upscaled) and how proud they were of that scene.

Well if you have a better source, or some visual way of contrasting it with the rest of the game aside from the resolution, you're welcome to post it.
 
Well if you have a better source, or some visual way of contrasting it with the rest of the game aside from the resolution, you're welcome to post it.

The interview was years ago, from prologue time, so I'm not gonna waste time looking for it, but the difference is pretty obvious from that to gameplay shots.
 

TheD

The Detective
yes ,it is .Technically it's (baked ) raytracing (camera mapping) + Realtime HDR.

Just looks like a run of the mill cube map on the car, it is low res and is most likely the same thing that they use in races for the reflections on the cars.
 

.hacked

Member
NxGFY.png


memories....
 

pottuvoi

Banned
Just looks like a run of the mill cube map on the car, it is low res and is most likely the same thing that they use in races for the reflections on car.
Did he just say baked?
If that is true it's the same as all developers do their lightmaps and nothing to do with reflections/shadows..
Also the method is used in hundreds of games.
 
Not sure I want to pursue this, but which parts of the image are you seeing a difference related to ray tracing?

Just the overall way the scene is lit and the accurate reflections. Also these scenes have to run at near 20 fps for some reason.

Here's some direct feed shots (but resized) from WaxVanillaFree:


granturismo5_105rgkbr.jpg

granturismo5_104bvkwg.jpg

granturismo5_103qykwu.jpg
 

.nimrod

Member
Just the overall way the scene is lit and the accurate reflections. Also these scenes have to run at near 20 fps for some reason.

Here's some direct feed shots (but resized) from WaxVanillaFree:
[..]

I don't know why that scene only runs at around 20 fps, but it's not rendered via raytracing. They're using standard shadow maps with only crappy hardware pcf filtering and the reflections aren't even accurate, the gas canister in the second pic for example should be blocking some the background reflection.
If anything it looks more like box projected cubemaps to me.
 
Well, I meant reflections on the car. Background reflections aren't even "real" reflections.

Much more apparent in motion and definitely much better then what you get in game.
 

.nimrod

Member
Well, I meant reflections on the car. Background reflections aren't even "real" reflections.

Much more apparent in motion and definitely much better then what you get in game.

But even those look like cubemaps, you can see the bilinear interpolation in the reflection on the hood
 

.nimrod

Member
How do cube maps reflect other objects? Cause even in game other cars are reflected during game play.


I'm not that knowledgeable in this things so pardon me if I say something stupid.

Yeah no problem, you just render each face of a cubemap each frame from the center of the car. The lighting model of realtime cubemaps is usually a lot simpler than the full frame rendering, diffuse lighting without shadows is often enough.

I'm kinda disappointed myself as i remember the interview about raytracing that scene, but i never got to buy the game so i didn't see it in detail before
 
How do cube maps reflect other objects? Cause even in game other cars are reflected during game play.

Cars are not reflected in other cars, if that's what you mean. Nor are the mechanics reflected in the garage or any other scene.

A cube map is made from 6 90 degree FOV pictures taken from a central point. In the case of the garage, this can be done pre rendered rather than real time, as the car never moves.

In the game, a very low detail version of the track is used to generate the cube map at the centre of the player's car, or in the case of replays, the car the camera is following (all cars will share identical reflections, so if your car is in a tunnel, all cars will reflect a tunnel environment regardless of their location. You can test that in photo mode.)
 
Cars are not reflected in other cars, if that's what you mean. Nor are the mechanics reflected in the garage or any other scene.

A cube map is made from 6 90 degree FOV pictures taken from a central point. In the case of the garage, this can be done pre rendered rather than real time, as the car never moves.

In the game, a very low detail version of the track is used to generate the cube map on the centre of the player's car, or in the case of replays, the car the camera is following (all cars will share identical reflections).

But they are, as is the road curbs, walls, and stuff like that.

Forza has them as well, although not on AI cars iirc.

*edit* Or maybe not, nm. I'm getting all my memory confused. I'll have to do some testing.
 

adelante

Member
But they are, as is the road curbs, walls, and stuff like that.

Woah wait, really? I've never seen this...And Forza only have cars reflected off on the hood, if you're in cockpit view... a neat framebuffer trick, which as far as I can recall, was first implemented in PGR4 and has since seen similar use in other racing games. Except GT5, which surprised me cos I don't remember seeing that effect at all...
 
But they are

Nope, not cars, I'd have seen it if it was there.

I can't remember but I think Forza has bonnet cam reflections which just map an upside down copy of the previous frame (everything before the HUD was drawn) to mimic a reflection, but some Codemasters PS2 games did this too.
 

adelante

Member
Nope, not cars, I'd have seen it if it was there.

I can't remember but I think Forza has bonnet cam reflections which just map an upside down copy of the previous frame to mimic a reflection, but some Codemasters PS2 games did this too.

I take back what I said then, neat. Driver San Francisco took an extreme approach and applied the frame to your whole car if you're driving around in third person.

GT3 was the first racer I've seen using realtime cube map reflections...blew my mind back then.
 
Nope, not cars, I'd have seen it if it was there.

I can't remember but I think Forza has bonnet cam reflections which just map an upside down copy of the previous frame (everything before the HUD was drawn) to mimic a reflection, but some Codemasters PS2 games did this too.

Yeah, Toca did it. But nm, I'm getting all confused with some of the stuff I had read a few years ago.

I was sure GT5 reflected cars but looking at shots on google makes it apparent they don't.
 

eso76

Member
well, it looked nice, but there really was no need to bother using ray tracing for a scene like that.
Yeah, you might have objects accurately reflecting each other, but it's nothing you can really appreciate in that scene, it could have looked almost 100% the same with the usual tricks.

We don't even need ray tracing so bad, at this point global illumination, light bouncing and ambient occlusion are far more important for graphical fidelty. All ray tracing does here can be faked with satisfying results anyway

Also, what kind of DOF are they using ? looks like a very cheap implementation, kinda like GT5's for objects close to the camera.


What I was wondering is...when are we going to see vector textures instead ? you know, textures which are not bitmaps but are actually vector based, like .ai files. Granted, that couldn't work for everything but i am sure in a few cases it would help.
 

.nimrod

Member
[..]
What I was wondering is...when are we going to see vector textures instead ? you know, textures which are not bitmaps but are actually vector based, like .ai files. Granted, that couldn't work for everything but i am sure in a few cases it would help.

Decals and fonts are sometimes rendered using distance fields preserving detail similar to vector graphics, there's a paper by valve about that: http://www.valvesoftware.com/publications/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf
 

eso76

Member
Nope, not cars, I'd have seen it if it was there.

I can't remember but I think Forza has bonnet cam reflections which just map an upside down copy of the previous frame (everything before the HUD was drawn) to mimic a reflection, but some Codemasters PS2 games did this too.

yep, some last gen games did.
True Crimes: los angeles did it too, unfortunately it grabbed the previous frame AFTER the HUD was drawn, so you'd see cars reflecting the hud too, or trucks reflecting themselves :)

As for cube mapping, it could be used to draw reflections of other cars too; just like it grabs a picture of (a simplified version of) the scene, there's no reason why said scene couldn't include cars, except performance of course. And of course you should have individual cube maps for each car for that to look convincing, since otherwise every car would be reflecting the yellow Corvette near the player. I still think that this would still be faster than raytracing in any case. and produce very similar results eventually.

Actually, someone told me that Bugbear's Flatout was already using individual cube maps for every car ? not sure.
 

Karak

Member
I thought i7s were overrated...why isn't he using a i5....could've save some cash.

or at least that is what message forums have told me.

edit- His GTA4 vid is amazing.... next gen is already here..I've been missing out. :(

Not if the framerate is 4 it isn't.

EDIT: Scratch that. Looks like the FPS is much higher than it was before. Good times.
 

Tess3ract

Banned
I thought i7s were overrated...why isn't he using a i5....could've save some cash.

or at least that is what message forums have told me.

edit- His GTA4 vid is amazing.... next gen is already here..I've been missing out. :(
I guess i'm weird because the most jarring thing to me in that video is the awful awful clutter popin. I hate that more than anything else in that video.
 
"All of them are rendered on a GPU, though not in real-time, so that should be indicative of what the future of raytracing/pathtracing should look like."


You could essentially link to any CG/renderer website and see renders just as good. That these were rendered using a GPU is not important. What's important is whether it's rendered in real-time or not.
 

3phemeral

Member
The problem with that is that everytime it gets realized, game complexity rises making it impractical again.

I remember this debate since a decade or more ago and I've retained the same position: Ray Tracing will never be viable in-game because there will always be cheaper, more cost-efficient techniques to perform similar functions.

Ray Tracing is just far too computationally expensive and like you said, games will always raise the bar for complexity with every generation, moving the goal post every time.

The only time I see RT becoming the standard for rendering is when we reach a point of diminishing returns and you can't tell what's graphically different from one generation to the next, even with a generational leap in power. But who knows what areas of interactivity we've yet to meddle in that will require even more visual processing power. I really don't think RT will be viable at all, unless they decide to use it on a game that's simple in every respect.
 
I remember this debate since a decade or more ago and I've retained the same position: Ray Tracing will never be viable in-game because there will always be cheaper, more cost-efficient techniques to perform similar functions.

Ray Tracing is just far too computationally expensive and like you said, games will always raise the bar for complexity with every generation, moving the goal post every time.

The only time I see RT becoming the standard for rendering is when we reach a point of diminishing returns and you can't tell what's graphically different from one generation to the next, even with a generational leap in power. But who knows what areas of interactivity we've yet to meddle in that will require even more visual processing power. I really don't think RT will be viable at all, unless they decide to use it on a game that's simple in every respect.

Yea I agree.
 

onesvenus

Member
True, but the cost of each ray traversal only increases by the log of the total number of polygons in the scene. With rasterization, rendering costs increases linearly with the number of polygons.

Well if you use space partition tecniques to sort the polygons as you would do with raytracing, I don't see how the rasterization cost is linear with the number of polys.
Raytracing does effectively solve a lot of hacks you have to do with rasterization techniques but in order to do so you'd need to bounce a lot of rays. I don't think there is any article comparing both approaches to effectively tell if a method is inherently faster than the other.
 
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