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OpenCL Voxel Splatting  by spacerat    -----


Time Spent: 10 days
Date Added: Aug 18 2012 09:04 PM

Since there are still lots of rumors around about unlimited detail, I wanted to give point based rendering at try and see how well it works in OpenCL.

It turned out that the performance is much better than basic point rendering in OpenGL. While OpenGL allowed me to render around 630M pts / sec, OpenCL reached 3-4 times the speed with ~2 Billion points per second on a GTX580M GPU.

Just rendering points does not lead to a smooth surface however. For that, a post-processing filter is required. It increases the size of the points and fills the holes. I have implemented a very simple one, to show that it works. As for the culling, only frustum culling is implemented. More advanced hierarchic occlusion culling might give extra frames especially in indoor scenes. Also a hierarchic depth buffer is not been used - it might further give additional performance when adapted to point based rendering.

Main challenge for the implementation was to find a data structure that allows parallel access by stil keeping the size per voxel reasonable. Rendering the points works pretty much straight forward.

In the image, you can see the render stages:
Right : Z buffer
Middle : Colored Points
Left : Including post processing


Render Resolution: 1024x768
Framerate: 30-40 fps

Scene Dimension: 20k x 1k x 20k voxels
Dataset : 1024x1024x1024 Voxels (single instance)
Data size per voxel: 4 bytes / voxel at each LOD, total ~5 bytes, seen over all LODs

The Demo is attached - not sure it works on all cards however.
Attached File  OpenCL.Voxel-Splatting.zip   9.3MB   2859 downloads

Alternative Download : http://www.2shared.c...-Splatting.html

Visual Studio Express

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seems after gamedev relaunch there're less comments.
update: ok changed already ;)
on my R6950/Cat.12.4 this demo shows nothing but a white window both in GPU and CPU mode, it doesn't report any errors in the console window
@guest: I would like to solve this issue - however that is difficult if there was no error shown
Can we expect to play with source code? I would like to fix AMD errors also as is my GPU Brand..
I dont have released the code so far.
If you have some time, you can help me testing & fixing it on ATI/AMD however
On my AMD 7770, I also just see a white window with no errors in both GPU and CPU modes.
not working on AMD FX + HD 7770 (blank window)
"For that, a post-processing filter is required. It increases the size of the points and fills the holes."
Please could explain this or attach some source code for reference of the weighted functions you choose? I'd like to try this, it sounds really cool.
The post-processing filter is actually similar to the one presented in this paper : http://wwwcg.in.tum.de/fileadmin/user_upload/Lehrstuehle/Lehrstuhl_XV/Persons/Kraus/pbg07.pdf
I love the look, so organic and anti-polygonized!

The demo runs fine but none of the controls work, including Esc...
yes it suits very well for high detailed organic stuff.
controls are not implemented - its a pure tech demo