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General News and accouncements regarding the Indigo render engine
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Behrendt
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Post by Behrendt » Fri Aug 25, 2006 5:09 am

Slow down m8 :lol: Dont wanna have 60 beta versions again :oops:

clipi
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Enhanced Metropolis

Post by clipi » Fri Aug 25, 2006 6:52 am

Hello Nicholas

Have you ever considered using Delayed Rejection or some other
Adaptive Metropolis method such the one introduced by Heikki Haario?
it seem that they can greately improve efficiency of MTL.

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Jedrzej_s
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Re: Enhanced Metropolis

Post by Jedrzej_s » Fri Aug 25, 2006 9:29 am

clipi wrote:Hello Nicholas

Have you ever considered using Delayed Rejection or some other
Adaptive Metropolis method such the one introduced by Heikki Haario?
it seem that they can greately improve efficiency of MTL.
clipi <- Can You show any examples of these methods ? Rendering time comparison or something ???

clipi
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Post by clipi » Fri Aug 25, 2006 10:55 am

Well this method as far as I know never were used in any GI application. But since Indigo is more an experimental render then it might be good to try some inovative aproach.
The concept of delayed rejection is like this acording to MIRA paper
(On Metropolis-Hastings algorithms with delayed rejection )

In a Metropolis-Hastings algorithm, rejection of proposed moves is an intrinsic part of ensuring that the chain converges to the intended target distribution. However, persistent rejection, perhaps in particular parts of the state space, may indicate that locally the proposal distribution is badly calibrated to the target. As an alternative to careful off-line tuning of state-dependent proposals, the basic algorithm can be modified so that on rejection, a second attempt to move is made. A different proposal can be generated from a new distribution, that is allowed to depend on the previously rejected proposal.


An adaptive Metropolis-Hastings scheme: sampling and optimization
Authors: David H. Wolpert, Chiu Fan Lee

We propose an adaptive Metropolis-Hastings algorithm in which sampled data are used to update the proposal distribution. We use the samples found by the algorithm at a particular step to form the information-theoretically optimal mean-field approximation to the target distribution, and update the proposal distribution to be that approximation.

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Jedrzej_s
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Post by Jedrzej_s » Fri Aug 25, 2006 11:03 am

interesting... :). We will see what Ono say ;).

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OnoSendai
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Post by OnoSendai » Fri Aug 25, 2006 11:32 am

Very interesting Clipi... will read the paper later

clipi
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Post by clipi » Sat Aug 26, 2006 10:52 am

Thanks Nicholas.. hope this will be usefull for GI!

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scaron
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Post by scaron » Sun Aug 27, 2006 8:12 am

could someone repost the first image that took 24hrs? i can't see the comparison :(

so at the moment it just looks like you have 13mins of an incomplete render
doer of things somewhat technical

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Jedrzej_s
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Post by Jedrzej_s » Sun Aug 27, 2006 11:59 am

Here is comparison:

- Render time: 13 min (new code):
Image

- Render time: 10 hours on 2 cores for each... (Indigo 0.5):
Image

Here is topic with this appartements final(s):
http://www.indigorenderer.com/forum/viewtopic.php?t=52

PakX
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Post by PakX » Mon Aug 28, 2006 1:16 am

Hi,

I think that this is not a very good comparison because the rendertimes a tooo diferent.

I will be look more impressive, when nick post a 13 minutes rendering rendered in an older indigoversion.

But anyway. Good job Nick!

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Jedrzej_s
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Post by Jedrzej_s » Mon Aug 28, 2006 7:15 am

Pak-X wrote:I will be look more impressive, when nick post a 13 minutes rendering rendered in an older indigoversion.
Yes, this would be better comparison or 2 finals renderings (first on old code and second on new code).

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OnoSendai
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Post by OnoSendai » Thu Aug 31, 2006 2:48 am

Ok.. another image

Image

Render time: 55 mins, single thread.
Yeah, there is a lot of noise, but it shows that bidir + MLT is usable for sunlit scenes now (cross fingers).
Left overnight with a couple of threads, it should be baked to perfection, I think :)

PakX
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Post by PakX » Thu Aug 31, 2006 3:10 am

Yes it looks very good. But I can just repeat my. I wanna see a Comparison between old and new Indigo :wink:

But it seems now being Maxwell-speed because it looks that its clean after 5 hours of rendering.

I look forward to you :)

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manitwo
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Post by manitwo » Thu Aug 31, 2006 4:22 am

:lol: :D :D :lol: :D :lol:

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Maluminas
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Post by Maluminas » Thu Aug 31, 2006 4:31 am

Yes i would like to see a comparison too, between the old code and the new code. :D

What i mean is: Render a scene with the old code for a set period of time, lets say 15 minutes. Then render the exact same scene with the new code for the same time, 15 minutes (also on same computer, same image size etc.). Post the two pics so we can compare the new code to the old code with the images. This way we can see and evaluate the difference in performance between the old and the new code. :P

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