Author Topic: 500x1 samples vs 1x500 samples - time difference  (Read 4421 times)

2013-09-22, 20:52:02

maru

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I've rendered two images using bucket mode but it could also be achieved with progressive:

500x1 - 500 path tracing samples rendered with 1 initial sample (equivalent of 500PTS x 1 pass in progressive mode)

1x500 - 1 path tracing sample rendered with 500 initial samples (equivalent of 1PTS x 500 passes in progressive mode)

I understand why there is a big visual difference but my question is: why is there such difference in rendering time? Why is sampling one pixel 500 times with 1 path tracing sample slower than sampling one pixel 1 time with 500 path tracing samples?

2013-09-22, 21:15:24
Reply #1

rafpug

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Hi maru,
nice ^ _ ^

As soon as I have some time I start seeing this method bucket

2013-09-22, 21:40:44
Reply #2

Ondra

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easy: there is additional overhead for primary rays. If there was none, having PT samples parameter would make no sense
Rendering is magic.
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2013-09-23, 09:57:21
Reply #3

maru

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2013-09-23, 12:03:57
Reply #4

Stan_Booth

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Maru, PT does not equal In.sample - it is your main mistake.
I use BM too and i'll show example for you later
« Last Edit: 2013-09-23, 12:08:45 by headoff »

2013-09-23, 14:10:50
Reply #5

maru

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Maru, PT does not equal In.sample - it is your main mistake.
Your main mistake is that you didn't understand what I wrote.

What I meant is: [path tracing samples] x [initial passes] in bucket mode is the same as [path tracing samples] x [passes] in progressive mode.

2013-09-24, 10:25:05
Reply #6

maru

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Ok, Headoff, you were right. But not entirely. Turns out that:

in progressive mode [path tracing samples] x [1 pass] = in bucket mode [path tracing samples] x [2 initial samples in bucket mode] x [pass]

Here is proof. If you view these images in some viewer and you can jump from one to another, even the noise is the same:

2013-09-24, 20:05:49
Reply #7

maru

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One more test showing that rendering a scene with

progressive: [X pt samples] * [Y passes]

is exactly the same as rendering it with

buckets: [X pt samples] * [X*2 initial samples]

phew


2013-09-24, 20:52:36
Reply #8

Stan_Booth

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as i understood when BM set 1/1/X - AA is OFF.  It's why we see such image without anti aliasing.
And i tested it until become clean image. I mean that settings pt 200  vs. 400/1 did same clean result. Like as you showed in your latest post
« Last Edit: 2013-09-24, 21:07:01 by headoff »

2013-09-24, 21:01:02
Reply #9

maru

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