Re: [Elphel-support] 10393 Imagers Synchronization

[Elphel Support]

Mohamed,



If you want to stitch images, you definitely want them synchronized (as we do 
with panoramic cameras). Without the synchronization you may consider them to 
have random times.



And in any case Exif file header contains the precise timestamps, so you may 
compare/use them.



Andrey



 On Wed, 08 May 2019 14:14:20 -0700 Mohamed Morsy  
wrote 


If the camera is in motion and we wanted to stitch together the frames from all 
4 imagers, would it be better to have them synchronized? If they weren't 
synchronized would the frames still match perfectly or would the offsets be 
noticeable?
 

Mohamed


From: Elphel Support <mailto:support-list@support.elphel.com>
 Sent: Wednesday, May 8, 2019 3:48:29 PM
 To: Mohamed Morsy; Elphel List
 Subject: Re: [Elphel-support] 10393 Imagers Synchronization  


Hello Mohammed,
 
 You can save camera settings so they will be precisely synchronized. In "free 
running" mode each sensor can have different WOI and so different FPS. You may 
find info on synchronization here: https://wiki.elphel.com/wiki/Trigger_393
 
 The disadvantage of synchronized mode is in low-light conditions, because when 
operated in free running mode rolling-shutter sensors can have exposure up to 
frame readout period (14.5 fps full resolution), exposure and readout overlap.
 
 In triggered mode exposure and readout are not overlapped, so frame period can 
not be below exposure time plus readout time. Other than that in triggered mode 
all sensors have beginning of exposure at exactly the same moment (to 
microsecond precision), same
 applies to multiple 393 camera if they are connected with sync cables
 
 Andrey
 
 



 On Wed, 08 May 2019 12:32:00 -0700 Mohamed Morsy 
<mailto:mmo...@redzone.com> wrote 


Hello Oleg, 

I understand that when 4 imagers are connected to the 10393, they are not in 
sync by default. Do you know how out of sync they are? Also, is the lack of 
synchronization noticeable? If the cameras are in motion, will there be 
significant gaps between the
 different imagers' frames? If this is something you've tested please  let me 
know.



Thank you,



Mohamed Morsy

RedZone Robotics


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Re: [Elphel-support] 10393 Imagers Synchronization

[Mohamed Morsy]

If the camera is in motion and we wanted to stitch together the frames from all 
4 imagers, would it be better to have them synchronized? If they weren't 
synchronized would the frames still match perfectly or would the offsets be 
noticeable?

Mohamed

From: Elphel Support 
Sent: Wednesday, May 8, 2019 3:48:29 PM
To: Mohamed Morsy; Elphel List
Subject: Re: [Elphel-support] 10393 Imagers Synchronization

Hello Mohammed,

You can save camera settings so they will be precisely synchronized. In "free 
running" mode each sensor can have different WOI and so different FPS. You may 
find info on synchronization here: https://wiki.elphel.com/wiki/Trigger_393

The disadvantage of synchronized mode is in low-light conditions, because when 
operated in free running mode rolling-shutter sensors can have exposure up to 
frame readout period (14.5 fps full resolution), exposure and readout overlap.

In triggered mode exposure and readout are not overlapped, so frame period can 
not be below exposure time plus readout time. Other than that in triggered mode 
all sensors have beginning of exposure at exactly the same moment (to 
microsecond precision), same applies to multiple 393 camera if they are 
connected with sync cables

Andrey




 On Wed, 08 May 2019 12:32:00 -0700 Mohamed Morsy 
mailto:mmo...@redzone.com>> wrote 

Hello Oleg,

I understand that when 4 imagers are connected to the 10393, they are not in 
sync by default. Do you know how out of sync they are? Also, is the lack of 
synchronization noticeable? If the cameras are in motion, will there be 
significant gaps between the different imagers' frames? If this is something 
you've tested please  let me know.

Thank you,

Mohamed Morsy
RedZone Robotics
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Re: [Elphel-support] 10393 Imagers Synchronization

[Elphel Support]

Hello Mohammed,

You can save camera settings so they will be precisely synchronized. In "free 
running" mode each sensor can have different WOI and so different FPS. You may 
find info on synchronization here: https://wiki.elphel.com/wiki/Trigger_393

The disadvantage of synchronized mode is in low-light conditions, because when 
operated in free running mode  rolling-shutter sensors can have exposure up to 
frame readout period (14.5 fps full resolution), exposure and readout overlap.

In triggered mode exposure and readout are not overlapped, so frame period can 
not be below exposure time plus readout time. Other than that in triggered mode 
all sensors have beginning of exposure at exactly the same moment (to 
microsecond precision), same applies to multiple 393 camera if they are 
connected with sync cables

Andrey





 On Wed, 08 May 2019 12:32:00 -0700 Mohamed Morsy 
 wrote 


Hello Oleg,

I understand that when 4 imagers are connected to the 10393, they are not in 
sync by default. Do you know how out of sync they are? Also, is the lack of 
synchronization noticeable? If the cameras are in motion, will there be 
significant gaps between the different imagers' frames? If this is something 
you've tested please  let me know.



Thank you,



Mohamed Morsy

RedZone Robotics


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