Sync Multi Cameras - 3d Modeling - page 2 - General Discussion and Assistance - CHDK Forum
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Sync Multi Cameras - 3d Modeling

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Offline waterwingz

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Re: Sync Multi Cameras - 3d Modeling
« Reply #10 on: 13 / October / 2012, 17:28:02 »
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Quote from: David Ripple on 13 / October / 2012, 16:51:19
It's not working with CHDK, do you have any suggestions?
You'll probably have to tell me a lot more about what you have done.  Simply saying "its not working" does not help.  How did you setup the choices in the Remote Parameters menu ?
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Offline David Ripple

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Re: Sync Multi Cameras - 3d Modeling
« Reply #11 on: 14 / October / 2012, 12:32:04 »
reyalp:  Thanks.  For now I'll stick to 1.1

waterwingz: After trying a couple different settings, it works.  I used:

Enable Remote: On
Switch Type: OnePush
Control Mode: Normal
Enable Synch: On

I did need to restart the camera after changing the above settings.

However, it seems like I'm not able to Override Shutter Speed.  I have tried the below settings with all other settings at default :

Override Shutter Speed: 1/30
Value Factor: 1 

The problem is ever time I set the Value Factor to 1, and then I press the shutter button no picture is recorded and I get a message in the lower left that reads:

*** STARTED ***
;)
*** FINISHED ***

Also in the upper left it says TV: 1/30, it might not be TV, but something close.  My eye sight isn't what it use to be. :)

I have also tried restarting my camera, but that just sets Value Factor to off.
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Offline waterwingz

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Re: Sync Multi Cameras - 3d Modeling
« Reply #12 on: 14 / October / 2012, 12:37:58 »
Quote from: David Ripple on 14 / October / 2012, 12:32:04
I did need to restart the camera after changing the above settings.
Hmmm ... doesn't sound right.

Quote
However, it seems like I'm not able to Override Shutter Speed.  I have tried the below settings with all other settings at default :
Override Shutter Speed: 1/30
Value Factor: 1 
The problem is ever time I set the Value Factor to 1, and then I press the shutter button no picture is recorded and I get a message in the lower left that reads:
*** STARTED ***
; )
*** FINISHED ***
That's because you are pressing the shutter switch while you are still in CHDK <ALT> mode.  In that mode,  pressing the shutter activates the current script.  In your case it activated the default script as you don't have anything else selected.  The defaults script does nothing but print a smilie.

Exit <ALT> and try it ?

Quote
I have also tried restarting my camera, but that just sets Value Factor to off.
There is an option in the menu to tell CHDK not to reset override setting on power up.
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Offline David Ripple

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Re: Sync Multi Cameras - 3d Modeling
« Reply #13 on: 15 / October / 2012, 02:50:40 »
waterwingz: great advice!  Exiting out of <ALT> made it so I don't need to restart for sync to work.  also, exiting out of <ALT> and setting CHDK not to reset override setting on power up fixed the shutter problem.

The sync on three cameras is very nice.  Here's a pic:


Maybe you have some helpful info on how to control aperture size.  I set the Override Suvj. DIst. V to many different setting.  From 100 to 1441 to 65535 and tried all the Value Factors.  I also set the AIAF to On, Off, and Face Detect.  But I do not see any difference in the focus, everything remains in focus.


Thanks.
« Last Edit: 15 / October / 2012, 03:08:29 by David Ripple »
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Offline Microfunguy

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Re: Sync Multi Cameras - 3d Modeling
« Reply #14 on: 15 / October / 2012, 06:02:00 »
Quote from: David Ripple on 15 / October / 2012, 02:50:40


The sync on three cameras is very nice.

Be aware that you cannot accurately measure synch using that method due to how the display is refreshed.

You have to use a CRT monitor.
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Offline waterwingz

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Re: Sync Multi Cameras - 3d Modeling
« Reply #15 on: 15 / October / 2012, 08:58:17 »
Quote from: Microfunguy on 15 / October / 2012, 06:02:00
Be aware that you cannot accurately measure synch using that method due to how the display is refreshed.
You have to use a CRT monitor.
True - its a question of how accurate you want to be.  From what you've posted,  good 3D of moving subject matter requires sub-millisecond response ?

LCD monitors essentially redraw the entire screen in parallel at a 60hz rate.  So the fastest difference you will be able to measure is about 30 mSec with a desktop monitor.

With a CRT,  the screen refresh rate is about the same (60 hz) but it is drawn by a fast moving electron beam.  You can actually photograph individual scan lines of that beam - each of which is draw at an approximate 16 uSec rate (1024x768 monitor setting at 60hz vertical refresh). The video I linked above shows this effect - you are essentially tracking the position of the electron beam rather than the complete refresh of the display image. Differences between pictures then come down to estimating the peak of the relative brightness differences between images - telling you where the electron beam was scanning at that moment in time.

« Last Edit: 15 / October / 2012, 09:34:33 by waterwingz »
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Offline Microfunguy

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Re: Sync Multi Cameras - 3d Modeling
« Reply #16 on: 15 / October / 2012, 09:33:10 »
Quote from: waterwingz on 15 / October / 2012, 08:58:17
good 3D of moving subject matter requires sub-millisecond response ?

The point is, you may not be aware of the fast-moving subject.

Someone can be standing very still in front of a fountain, waterfall, river, etc and you will need sub-millisecond synch to capture that.

Your brain will instantly detect the tiniest details that do not quite 'add-up' in its millions of years of experience of the World.

The result is very distracting.

Not sure why the crudest synch would not work for 3D modelling.

In passing, the 3D models that I have seen always seem to have scruffy bits and anomalies and crude resolution.

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Offline Nestkast

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Re: Sync Multi Cameras - 3d Modeling
« Reply #17 on: 21 / October / 2012, 09:01:31 »
Would inverted remote give beter sync results?

http://chdk.setepontos.com/index.php?topic=1140.0
Or is the new method beter? I have no CRT monitor to proper test this.


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Offline waterwingz

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Re: Sync Multi Cameras - 3d Modeling
« Reply #18 on: 21 / October / 2012, 09:15:29 »
Quote from: Nestkast on 21 / October / 2012, 09:01:31
Would inverted remote give beter sync results?
http://chdk.setepontos.com/index.php?topic=1140.0.  Or is the new method beter?
That post basically describes how it actually now works. The sync operation allows the shutter to fire when the USB voltage goes away.  Your link is to a very old post which I assume was before the sync code was added to CHDK so the OP is using scripting to try and get more accurate sync.

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I have no CRT monitor to proper test this.
I almost hate to say this,  but CRT monitors are now considered toxic waste - you pay someone to dispose of perfectly good working units.   I'll bet you could get one for free if you looked around.

P.S. :  almost forgot to say "thank you" for taking the time to actually read through old forum postings - there is a lot of information there but its sometimes painful to try and dig it out - especially with all the improvements to CHDK over the years.
« Last Edit: 21 / October / 2012, 09:19:24 by waterwingz »
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Offline Nestkast

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Re: Sync Multi Cameras - 3d Modeling
« Reply #19 on: 21 / October / 2012, 09:54:08 »
Thanks now I know I don't have to use the inverted remote script anymore.
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