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Interactive Indirect Illumination Using Voxel Cone Tracing

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darkwings
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Interactive Indirect Illumination Using Voxel Cone Tracing

Postby darkwings » 19.08.2011, 18:17

First of all apologies if this has been discussed before.



So I just found this Global Illumination technique, to me this vaguely looks similar to LPV.
But this looks kind of superior to LPV, I don't know the exact technical details so I might be wrong. Hopefully you guys can throw some light on this :D
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby ClockworkOnion » 24.08.2011, 03:53

needs sound
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby martin.hedin » 09.06.2012, 19:02

Bump. Now that we have seen this tech in UE4, will CE3 be having an overhaul of its GI system?


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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby WPhoeniXW » 09.06.2012, 19:42

CE 3 wins at the start .
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby martin.hedin » 09.06.2012, 19:44

WPhoeniXW wrote:CE 3 wins at the start .


Do you mean that they will upgrade the GI or not? :meh:
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby Ultimarage » 12.06.2012, 12:09

I think the particle system in CE3 needs upgraded more. That, and the extremely limited tessellation implementation.

CE3 currently can't handle a million particles like UE4.
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby BmB » 12.06.2012, 12:31

Isn't the only reason that UE4 can handle millions of particles because of CUDA particles? Which is nice for tech demos but 1000% useless in practise. CUDA-tech is dead end because no dev with any sense is going to use a single-vendor solution for anything more than gimmicks. And gamers certainly won't appreciate it.

If Crytek can come up with compute-shader or opencl particles maybe we have a winner on our hands.
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby the_grim » 12.06.2012, 12:50

Crytek's Light Propagation Volumes tech demo looked very similar in quality - it's easy to make a comparison since both demos are showcased in the Sponza atrium model... :P

http://www.youtube.com/watch?v=vPQ3BbuYVh8

Both techniques are very much alike, too. I'm not that much in the know about the technicalities, but to me a voxel octree seems very similar in nature to a cascaded light propagation volume. Both are rendering reflective shadowmaps for the lightsources that contribute to GI, and use the RSM to distribute virtual point lights into the scene which in turn inject directional, coloured illumination data into the voxel octree/LPV.

Light Propagation Volumes are capable of multiple bounces, as well as secondary occlusion, although it looks very accurate in the voxel cone tracing video. LPVs can do specular reflections too, but the reflections in the video in the OP look insanely accurate! 8o Wonder how it runs in an actual game scenario though - the LPV in Crysis 2 are lower-density than in Crytek's original demo, and GI is only calculated for the sunlight although the tech itself doesn't restrict the amount of lightsources that can contribute to GI. It's all about performance in a practical situation. ;)
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby BmB » 12.06.2012, 13:09

There really is no comparison with LPV. LPV is blobby and inaccurate.
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby the_grim » 12.06.2012, 13:18

BmB wrote:There really is no comparison with LPV. LPV is blobby and inaccurate.

Not if you crank up the settings as much as they did in the voxel cone tracing demo. "Blobby and inaccurate" isn't an intrinsic property of a volumetric grid, it's a property of a low-density volumetric grid. :rolleyes: Crytek's LPV demo (from 2009) was nearly similar quality. There's no telling how much they'll have to downgrade the voxel octree settings for it to run feasibly well in an actual game scene. ;)
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby BmB » 12.06.2012, 13:23

It certainly wasn't, it was just a best-case showcase. i.e. one flat surface directly opposite another flat surface. If you check the furniture demo or the demo with the Crysis 1 assets you'll see the same inaccurate blobbiness.
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby the_grim » 12.06.2012, 13:48

Note that a voxel octree is a volumetric grid too. It's all about how dense you make the grid (seems to be insanely dense in the cone tracing showcase video to produce such sharp reflections). Maybe they did some magic to make it run significantly better than LPV though?
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby BmB » 12.06.2012, 15:35

An octree has potentially unlimited density with little waste (the whole point of an octree). Evidently they are using some sort of generated voxel representation and raytracing into that (raytracing voxels in an octree is supposedly extremely efficient) or using some sort of approximate raytracing of some sort since they call it "cone tracing".

Kind of like a geomerics solution with an automatic proxy mesh (as opposed to handcrafted, and dynamic) that is extremely efficient to approximately raytrace.

It's a very interesting solution for sure. Almost makes me wonder if you could just use vertices directly for it instead of voxels, skipping the potentially expensive voxel generation step and making the reflections more accurate at the same time.
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby the_grim » 12.06.2012, 15:55

Yeah, it certainly looks impressive, but I'm wondering about the amount of data they need to store in the voxel octree - and pull from it every frame - not so much the efficiency of ray/cone tracing it...
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Re: Interactive Indirect Illumination Using Voxel Cone Traci

Postby Cry-Styves » 13.06.2012, 00:45

The author states in the paper that it requires over 1GB of memory for the voxel data. Quite a bit I'd say, especially since that was for the sponza scene.


 
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