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Multi-camera setup project.

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Offline reyalp

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Re: Multi-camera setup project.
« Reply #400 on: 26 / November / 2016, 15:40:04 »
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PS : its a bit of big trouble to upload your script to every mounted camera and single-test it on each one of them...
There is no reason whatsoever to upload it to every camera.

Just running it on one camera/sd card combo, you could use to quickly test the effect of different settings, like image size and so on.

You can also use it on a few cameras (or the same camera with a few different cards) to verify that the SD card accounts for the difference.

Running it should also give you good idea of maximum practical shooting rate for a given combination of camera/card/settings.

Because it's a separate, much simpler implementation, it also gives us a check whether the problems you are seeing with multicam are really the limit of the camera, or some bug in multicam.

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So if the writing speed of sd cards was the suspect , then ixus 160 should must have achieved larger interval times since they had to write bigger image files (20mp vs 16mp) and the sd cards are not that speedy as class6 cards of A2500s...
I would not assume this, because there are other significant hardware differences, and the byte size of the file depends on the scene and jpeg quality too. Test and let the data tell the story.

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So i come down to what you said , that "busy" time between shots is not necessarily meaning "saving to sd card" .Maybe means "i process the image , wait a bit" thing?
Most often, it's shown when doing noise reduction at high ISO or dark frame subtraction for long exposures, but it might show up for other reasons. It's possible it could even show up as a side effect of CHDK blocking the shooting process.

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And maybe ixus 160 cameras have faster image processor than A2500s and thats why they achieve lower interval times?
I can confirm that having the same Digic number does not mean identical performance. Newer Digic IV definitely have faster SD and USB performance than old ones, and I wouldn't be surprised if they have faster image processing too. Different cameras can have different amounts of memory, and different image quality settings too.
Don't forget what the H stands for.

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Offline mphx

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Re: Multi-camera setup project.
« Reply #401 on: 26 / November / 2016, 18:46:22 »
@reyalp


Since i wont be to the studio until late next week , i will upload the script to ixus cameras i have here at home and do some tests.
Results will be different from A2500 , but i can get an idea , what (sd,image size,settings,etc) affect the shooting times.

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Offline mphx

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Re: Multi-camera setup project.
« Reply #402 on: 27 / November / 2016, 10:00:33 »
@reyalp


I did some tests today with ixus 160 and your script .Lets sum up the parameters of the experiment :)


1.Camera : Canon ixus 160
2.SD card 128mb Class 4 (?) : write (raw) : 4116 kb/s , write (mem) : 4096 kb/s , write (64k) : 3947 kb/s (chdk benchmark)
I tested a known class 4 and had similar results , so i consider this SD card to be a class 4.
3. SD card 16gb Class 10 : write (raw) : 18952 kb/s , write (mem) : 18070 kb/s , write (64k) : 9416 kb/s (chdk benchmark)


So the two cards have significant difference at write speed.

Test #1

SD card 128mb Class 4
tv96 = 672
ISO = 1600
image size = L (average of 5mb file size)
interval = 1000msec (i know that camera cant get this time , so it will shoot as fast as possible.)

Test #2


SD card 16gb class 10
tv96 = 672
ISO = 1600
image size = L (average of 5mb file size)
interval = 1000msec (i know that camera cant get this time , so it will shoot as fast as possible.)

Test #3

SD card 128mb Class 4
tv96 = 512
ISO = 100
image size = L(average of 1mb file size)
interval = 1000msec (i know that camera cant get this time , so it will shoot as fast as possible.)

Test #3 settings are the settings we use at studio , where we have strong lights , but at my house where lights are lower , images were darkish and so i dont know if this test has any meaning at all.Results are here ->
https://www.dropbox.com/s/86n4d6ulc2e5qlp/ixus160_benchmarks.xls?dl=0
I made an xls with formatted cells , because the produced csv file is a bit messy :)
Have a look if you like to make any remarks and comments.

What i noticed is that apparently different sd cards , dont have any impact on shooting speeds if i read the results correctly.
Also in test #3 , a lower interval time (comparing to tests #1 and #2) is achieved , although as i said i dont know if this test has any practical meaning.

You made the script , you can "read" the results better than me , any comments will be helpful.

EDIT : i made 2 new tests..configuration is Test #1 and i changed the image size (m1 = 10mp , m2 = 3mp) , to see if there is some delay due to image processing.
I updated the xls file ( https://www.dropbox.com/s/86n4d6ulc2e5qlp/ixus160_benchmarks.xls?dl=0 ) (link as i see is identical with the one above...)

I noticed something interesting , interval achieved when going to M2 image size is identical with the interval achieved with L image size.At M1 size , interval increases , not much , but increases.
« Last Edit: 27 / November / 2016, 12:09:10 by mphx »

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Offline reyalp

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Re: Multi-camera setup project.
« Reply #403 on: 27 / November / 2016, 14:35:09 »
Test #3 settings are the settings we use at studio , where we have strong lights , but at my house where lights are lower , images were darkish and so i dont know if this test has any meaning at all.
We're not interested in the images, that's why the shutter speed is fixed (I guess you edited it to 1/40th for test 3) Otherwise, if you shoot in dim lighting, the camera might choose say, 1/2 sec exposure which would throw off the results.

The content of the image may affect the result, because the file size can change a lot depending how much detail there is.

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I made an xls with formatted cells , because the produced csv file is a bit messy :)
In general, I'd rather have the original data, but no need to re-post it for this run.

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interval = 1000msec (i know that camera cant get this time , so it will shoot as fast as possible.)
It looks like this was actually 0, but that has the same effect. The code where it says "for PTP testing" is only used if you didn't run the script from the script menu.

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What i noticed is that apparently different sd cards , dont have any impact on shooting speeds if i read the results correctly.
This does seem to be true in this case, the total variation is only ~200ms and most of that does not seem to depend on the card.

Some observations:
The CHDK benchmark "write (64k)" speeds are quite close to the nominal speed class. The class 10 card does much better with larger writes (raw and mem)

The first class 4  L results are slightly odd: If the image is ~5 MB, it should take > 1s at 4 MB/s. But the ready_time - raw_time is only 660ms. So maybe there is buffering going on, with the actual write finishing in parallel to the next shot.

You are right that test 3 is a bit faster, even though the exposure time is ~25 ms rather than ~0.8ms. You can see the longer shutter shutter in raw_time (910 vs ~880-890 in most other runs). I expect this difference is due to the ISO, because ISO1600 usually adds some processing for noise reduction, but the file size is also lower (likely due to lower noise and maybe also being very underexposed) so that could be a factor too.

I agree test 4 is a bit slower than the equivalent L shots. This matches previous experience that resizing has some performance penalty. In test 5 (M2) the smaller amount of data might compensate for the overhead of resizing. But in any case, the differences aren't large. IIRC, the impact of resizing was much larger on Digic II cameras.

So overall conclusion is none of this make much difference on this camera. I wouldn't assume that A2500 behaves exactly the same.
Don't forget what the H stands for.


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Offline mphx

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Re: Multi-camera setup project.
« Reply #404 on: 27 / November / 2016, 15:13:21 »
@reyalp

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We're not interested in the images, that's why the shutter speed is fixed (I guess you edited it to 1/40th for test 3) Otherwise, if you shoot in dim lighting, the camera might choose say, 1/2 sec exposure which would throw off the results.The content of the image may affect the result, because the file size can change a lot depending how much detail there is.


That's my point , with the fixed shutter speed and my low lights at home , images were darkish , less details , less size.
I wanted full image size (as much details as possible) , so we can see how the write speed affects the process.
If the image size is some kilobytes , then no conclusion can be safely exported.
Thats why i picked high iso at the first tests.
Lowering shutter speed and iso even more at test3 , i had to turn every available light in the house , and again images were a bit darkish...

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It looks like this was actually 0, but that has the same effect.

Yes i figured it out at the end :)


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(I guess you edited it to 1/40th for test 3)


Yes i edited the lua.

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So overall conclusion is none of this make much difference on this camera. I wouldn't assume that A2500 behaves exactly the same.


Yes i need to repeat the tests with A2500s (test one A2500 with class4 card and one with class 6) , with the settings we are using at the studio , all lights turned on.
« Last Edit: 27 / November / 2016, 15:14:59 by mphx »

Re: Multi-camera setup project.
« Reply #405 on: 23 / January / 2017, 16:28:39 »
I did not read all 41 pages of this thread, but am working on it. Will take a week probably.
Anyways. what software is best for quickly post processing the images and outputting to a big 55" tv?
I want to make a 12 or more camera array for events where people jump or do other cool action moves and them within a few minutes the results are displayed for them to see.
I have seen optical flow and adobe after effects mentioned, but after searching google for a few days dont' see a single tutorial. Thanks in advance for any ideas.

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Offline mphx

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Re: Multi-camera setup project.
« Reply #406 on: 23 / January / 2017, 18:59:33 »
I did not read all 41 pages of this thread, but am working on it. Will take a week probably.
Anyways. what software is best for quickly post processing the images and outputting to a big 55" tv?
I want to make a 12 or more camera array for events where people jump or do other cool action moves and them within a few minutes the results are displayed for them to see.
I have seen optical flow and adobe after effects mentioned, but after searching google for a few days dont' see a single tutorial. Thanks in advance for any ideas.

I can't say that i understood what you are trying to do.
What's your endgame?Create 3d model for some use?If yes consider the following.

1.You can't produce any "serious" 3d model with 12 cameras.You need...MANY. Like 60+
2.People must be STILL..not moving.They can take any pose they like..but keep it STILL during the shooting.

If you are not going to create 3d model from all this thing..desribe it better and i will try to be of any help :)

Re: Multi-camera setup project.
« Reply #407 on: 23 / January / 2017, 19:13:32 »
thanks for the response. I do not want to make 3d models I want to make a time slice bullet time effect video/gif.


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Offline mphx

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Re: Multi-camera setup project.
« Reply #408 on: 23 / January / 2017, 19:22:55 »
I have no experience with bullet time effect things.
But 12 cameras seem awfully few for such a project too...we are talking about a very thin..slice :)
You will have either position them far from each other so the video will be lacking frames..or too close to each other and you will have a very smooth but very small duration video.
Anyway i have no idea about these things..your problem is how to produce the video to display in a matter of few mins...
No idea..sorry..probably some video editing software?

Re: Multi-camera setup project.
« Reply #409 on: 23 / January / 2017, 20:31:47 »
yes it will be a very small slice, thanks for trying.

 

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