Re: Raytracing and modern Render Engines

On May 24, 12:46 pm, "Pixel.to.life" <pixel.to.l...@xxxxxxxxx> wrote:
On May 24, 11:53 am, "stefanba...@xxxxxxxxx" <stefanba...@xxxxxxxxx>
wrote:



On May 22, 12:23 pm, "Pixel.to.life" <pixel.to.l...@xxxxxxxxx> wrote:

On May 21, 9:02 am, Andy <andr...@xxxxxxxxxxxxxxxxx> wrote:

Hello,

i just have a simple question. I think so.
I read a bit aboutraytracing. I found out that this mechanism is good
for getting Pictures of high quality but bad in performance. So my
question is, which techinique is used by the modern render engines
like OpenInventor, GLScene, Irrlicht, .... ?? Because there is a
really fast real time rendering.
Could you pls tell me... thx a lot.

Andy

If an engine says it is using ray-tracing, and given real-time
performance, it is most probably using some sort of
hardware(+software) acceleration. There are ways to use GPUs for ray
tracing. There are also software based methods to accelerate ray
tracing computations, standard ones being ealry ray termination,
hierarchical object space intersection detection, etc... but pure
software based ray tracing is unlikely to give real time performance,
unless there are other things behind the scene as view dependent
rendering, progressive rendering etc.

In most recent graphics cards, approximately equivalent quality
results can be obtained by using 'real-time rendering' techinques,
that efficient exploit buffers and shading pipelines on the GPU.

Experts on the forum might be able to provide more information, some
of which could be proprietary - hence out of reach though.

Good luck,

Pixel.To.Life
[http://groups.google.com/group/medicalimagingscience]

Pixel.To.Life > There are ways to use GPUs for ray tracing.

Can you provide reference to the _speedup_numbers_ of GPU based/
assisted ray-tracer vs. CPU based? The numbers I've seen was 3 times
on 8800GTX against P4-3.6Ghz (single core). Based on my experience I
would expect that dual x5365 would be probably 7-8 times faster (8-
cores 3GHz duo core2) for ray-tracing than P4-3.6Ghz.- Hide quoted text -

- Show quoted text -

Hi, Stefan,

Here is a thesis that gives some idea of performance between 3 CPU
configurations, and an NVidia GPU configuration:

http://gpurt.sourceforge.net/DA07_0405_Ray_Tracing_on_GPU-1.0.5.pdf

Here is another dissertation:

http://graphics.stanford.edu/papers/tpurcell_thesis/tpurcell_thesis_l...

Pixel.To.Life.

Here is a thesis that gives some idea of performance between 3 CPU
configurations, and an NVidia GPU configuration:
http://gpurt.sourceforge.net/DA07_0405_Ray_Tracing_on_GPU-1.0.5.pdf
Here is another dissertation:
http://graphics.stanford.edu/papers/tpurcell_thesis/tpurcell_thesis_l...

Yes, I've read these articles; anyway thanks. Both of them have
compared GPU vs. single core CPU and both have demonstrated the
implementations which are hardly faster then single core CPU ray-
caster they compared. I've read recently _noticeably_ better results
on G80 but it is still far too slow to be encouraged about GPU ray-
tracer vs. multi-core CPU ray-tracer. By the way, I've failed to find
3-CPU configuration setup in both of these articles.

http://graphics.stanford.edu/papers/tpurcell_thesis/tpurcell_thesis_lowres.pdf
"All of our results are generated using a GeForce FX 5900 Ultra and a
3.0 GHz Pentium 4 CPU with Hyper Threading and 2.0 GB RAM."..."The
result is high performance code competitive with the best known
CPU implementations."

http://gpurt.sourceforge.net/DA07_0405_Ray_Tracing_on_GPU-1.0.5.pdf
"Figure 6.11.: CPU vs. GPU: Different Iterations: Pentium 4 [2.0 GHz]
vs. NVidia
GeForce 6800 Ultra"

Thanks,
-sb

.

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