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Author Topic: Wrong camera calibration - adjusted focal lenght too off  (Read 1409 times)

michaldolnik

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Wrong camera calibration - adjusted focal lenght too off
« on: September 29, 2022, 04:32:59 PM »
Hello,

Last 2 weeks we had issue with DJI M300 + P1. Point cloud (allign photos) was just so messy, whole goemetry was just wrong. Later i find out, that agisoft, when calculating camera geometry (f, k and p coeficients) calculate f to, I assume, very high values. 35mm lens he adjusts to 200mm!. We have the solution - lock f parameter at the beginning. However, this could case some precision errors. This problem occured just on one drone/camera setup, later it started on the other one as well. My guess is it is some new DJI crap update or agisoft bug, any ideas?

Paulo

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Re: Wrong camera calibration - adjusted focal lenght too off
« Reply #1 on: September 29, 2022, 04:40:55 PM »
Hello michaldolnik,

curious to know if you flew with drone not turning at end of each line, i.e. first line drone goes forward, 2nd line drone goes backward,... This could be the source of your issue as flying with a constant yaw, introduces high correlation between some io parameters and eo....
Best Regards,
Paul Pelletier,
Surveyor

michaldolnik

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Re: Wrong camera calibration - adjusted focal lenght too off
« Reply #2 on: October 03, 2022, 11:29:51 AM »
Yeah, were using DJI pilot to plan mission. As long as i know, it turns at the end of every line. However, we have been using it this way for years literally and this problem started to occur just last week or so. The first project was recently flown, second one back on May so it looks like this could be caused by agisoft, not by some M300 software.

Alexey Pasumansky

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Re: Wrong camera calibration - adjusted focal lenght too off
« Reply #3 on: October 03, 2022, 12:37:53 PM »
Hello michaldolnik,

Can you please share the problematic project (saved with the alignment results) to support@agisoft.com?
Best regards,
Alexey Pasumansky,
Agisoft LLC

michaldolnik

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Re: Wrong camera calibration - adjusted focal lenght too off
« Reply #4 on: March 20, 2023, 10:22:35 AM »
Hallo Alezey,

we have posted this problem also in the support forum.

Can you help us to resolve this issue?


Link is here:
https://agisoft.freshdesk.com/support/tickets/182448

JMR

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Re: Wrong camera calibration - adjusted focal lenght too off
« Reply #5 on: March 23, 2023, 01:48:58 AM »
Hello, michaldolnik
I suggest you to carefully inspect geotags.
I have seen some cases where really bad geotags are wrongly qualified as accurate as a few centimetres while just watching the coordinates one can see they are wrong.
When you load pictures in a new project you will see the blue balls representing camera locations. watch and see if there is any obvious blunder or misplaced ball.
if you see something suspicious, just uncheck the box for the suspicious photos. If they are tagged as accurate, they can potentially causing a strong bias in both exterior orientation and interior params.

Best regards
José