Making .cal from .tak

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SubmarineCables
Posts: 5
Joined: Tue Mar 09, 2021 5:12 am

Making .cal from .tak

Post by SubmarineCables » Tue Mar 09, 2021 5:38 am

Hello,

I use 4 Optitracks cameras to track the position of a semisubmerged sample on an experimental test rig. I recently calibrated the cameras, but the software crashed before I accepted the calibration. I didn't realise this because the calibration take file was present so I continued with my long and arduous setup, only to find that I don't have a .cal file. The volume is crowded with parts of the experiment so I need to calibrate before I assemble the rig.

Is there anyway I can make the .cal file now? The data is there and the cameras probably haven't moved (I can check this using the accuracy tool). I have tried loading the .tak file in the calibration pane but I can't proceed to calculate.

I'm fairly new to using Optitrack/Motive and have limited experience but can't find a solution online.

Thank you for your time.

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
Posts: 614
Joined: Mon Jan 19, 2015 11:52 am

Re: Making .cal from .tak

Post by steven.andrews » Tue Mar 09, 2021 12:55 pm

Hello SubmarineCables,

If you have a take that contains your calibration, you can export the calibration file from that. While you have the take open, just File->Export Camera Calibration.

When you go back to live, you can File->Open the calibration that was exported from the take.

I hope this helps!
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
wiki.optitrack.com
support@optitrack.com

SubmarineCables
Posts: 5
Joined: Tue Mar 09, 2021 5:12 am

Re: Making .cal from .tak

Post by SubmarineCables » Wed Mar 10, 2021 4:03 am

Hi Steven,

Thank you for replying. I did eventually find the offline calibration guide.

I need to validate the calibration now but when I open the accuracy tool the Wand Measurement box says searching for 500.00mm wand when I used a 250.00mm wand during calibration. I have run a short capture and checked the correct .cal file is open and I have checked the screenshots I took at the end of wanding that show I used a 250.00mm wand.

Will it auto-detect the wand?

steven.andrews
NaturalPoint Employee
NaturalPoint Employee
Posts: 614
Joined: Mon Jan 19, 2015 11:52 am

Re: Making .cal from .tak

Post by steven.andrews » Wed Mar 10, 2021 9:47 am

My pleasure,

When using the accuracy tool, Motive should look for the wand that is currently selected in the Calibrate pane. Unfortunately, I believe this was not working correctly for Motive 2.2. This should be fixed again going forward.

For the time being, you could select the two markers to measure their distance, and compare to what is expected.

Cheers,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
wiki.optitrack.com
support@optitrack.com

SubmarineCables
Posts: 5
Joined: Tue Mar 09, 2021 5:12 am

Re: Making .cal from .tak

Post by SubmarineCables » Fri Mar 12, 2021 4:28 am

I see, that makes sense as everything said 250.00mm wand. Thank you again.

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