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vipvip wrote:just few tests with new PMC engine:
i know it's just the beta of the future beta but i obtain regulary this problem: a splitted screen with 2 diffrents results, fotr the same rendering:
( see attached ) .
Perhaps it's because i use 2 card simult. for rendering ( multigpu with 2 gtx470 ) ?
We know. That's why we said, that multi-GPU doesn't work in beta 2.47
Cheers,
Marcus
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra
Here is my comparison which I think shows both the strength and weakness of the new PMC kernel. Both images were left to converge for 30 mins on a single GTX480.
As you can see PMC does a fantastic job of reducing noise on this difficult scene, however it seems to lack the full degree of colour bleeding and spread of indirect light shown in the pathtracing solution. This is most apparent in the shadow colour of the droids closest to the light source and the extra illumination of droids on the outskirts of the image.
Hopefully these discrepancies can be addressed in future updates but for a first look this is very promising.
Also, not sure if it has been mentioned elsewhere, but what does PMC stand for? Just curious.
Also I'm wondering if dispersion can be tied directly to ior? I don't have a deep understanding of the maths behind it all but I always thought both fresnel reflectivity and spectral dispersion were both tied directly to the ior. It would be great if we only had to specify the ior on a specular material and get correct reflections and dispersion automatically.
FIXED EDIT: The original PMC spec 30min shot was human error, I have uploaded a fixed version. There is still a noticeable difference in lighting compared to the PT solution.
UPDATED UPDATE: Turns out it was not human error, and was instead some sort of intermittent bug. I am currently putting together another post to show how the specular PMC solution progresses over time, and I will address this bug there. Hopefully I will find a way to reproduce it before then. Scene files will be included.
FINAL UPDATE: some of these issues seem to have been caused by a non-zero rrprob, I have gone through all my settings and will be making a definitive follow-up post.
Attachments
Last edited by Scog on Mon Jun 06, 2011 1:03 am, edited 5 times in total.
Scog wrote:Here is my comparison which I think shows both the strength and weakness of the new PMC kernel. Both images were left to converge for 30 mins on a single GTX480.
As you can see PMC does a fantastic job of reducing noise on this difficult scene, however it seems to lack the full degree of colour bleeding and spread of indirect light shown in the pathtracing solution. This is most apparent in the shadow colour of the droids closest to the light source and the extra illumination of droids on the outskirts of the image.
Hopefully these discrepancies can be addressed in future updates but for a first look this is very promising.
Also, not sure if it has been mentioned elsewhere, but what does PMC stand for? Just curious.
Also I'm wondering if dispersion can be tied directly to ior? I don't have a deep understanding of the maths behind it all but I always thought both fresnel reflectivity and spectral dispersion were both tied directly to the ior. It would be great if we only had to specify the ior on a specular material and get correct reflections and dispersion automatically.
EDIT: Added 2 more examples with a Dense flint glass SF10 material. This example shows even more significant differences between the 2 kernels. I'm actually surprised by the extent of difference in brightness here. The emitter appears stronger for some reason in this one, while refractions are dimmer. Very odd. The shape of the leg shadows is also of note.
Thanks for those images. Could you please post the kernel settings you used for path tracing and PMC? I think those differences are not correct and we have to investigate those.
Regarding dispersion and the refraction index: Both are not tied together. Dispersion is the effect that light of different wavelengths (color) has different refraction indices. How much they differ depends on the material. And often you dont want to use dispersion at all, since it introduces spectral variance (noise), but no visible difference when the image is converged.
Cheers,
Marcus
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra
Sc4rfy wrote:Thanks for your hard work Refractive. Wonderful release!
I've notice that when i use pmc i can use my pc normally, it's not slow, instead when i use pathracing i can't use my pc for other works
The time of render with pmc is bigger but the possibility to use the pc for others works is great!
Yes the observation is correct that your UI response is more fluent when you use PMC. The reason is that the work chunks are much smaller than in path tracing / direct lighting. We will improve that for those two kernels in the future, too.
Cheers,
Marcus
This is great
Typing this, whilst rendering a large scene on PMC in the background.Also I have been drawing up plans in AutoCAD as well as downloading a large file off the internet at the same time as well.
All on 1 GTX 460.
so even though it slows the rendering down a bit.I can get on with other work in the meantime and just let it cook in the background a bit longer.Productivity would therefore not be affected.
So i am really looking forward to the smaller work chunks in pathtracing and direct lighting on the new kernel in 2.5.
For those of us with only one card this will be great.
