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Author Topic: Coded targets detection failed  (Read 2616 times)

Yoann Courtois

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Coded targets detection failed
« on: June 15, 2017, 02:36:23 PM »
Hi everyone !
(I would say "Hi Alexey" but maybe somebody else has faced to this problem)

I've handle a couple of aerial measurements using UAV (DJI Phantom 4 Pro) and coded target (circular 12 bits) as GCPs.
As I presented in other topics, I have had lots of test to determine the minimal size of target regarding the GSD, so my following problem does not concern target size.

My surveys were composed of around 1500 pictures for an area of 15ha. 18 targets were set on the floor and measured using GNSS RTK.

The problem is that the target detection struggle to get all the visible targets on pictures. I would say for a 1/3 of targets, they are detected on all pictures, for a 1/3, detected on only a couple of pictures, and for the last 1/3 of targets, nothing is detected.

I attached a set of 4 pictures that show there is no link with distance / size / angle or whatsoever. Indeed on pictures 1 and 4 the target 9 is detected, but not in the pictures 2 and 3.
I got the same result for tolerance 30 and 100...

If somebody can help... Everything was OK before.
Regards
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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Yoann Courtois

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Re: Coded targets detection failed
« Reply #1 on: June 15, 2017, 02:37:04 PM »
Pictures 3 and 4 here:

(It's only an example, most of the pictures were facing down)
I may send you the pictures if needed.
« Last Edit: June 15, 2017, 02:38:59 PM by Yoann Courtois »
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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Alexey Pasumansky

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Re: Coded targets detection failed
« Reply #2 on: June 15, 2017, 02:40:28 PM »
Hello Yoann,

Can you please send a couple of original images where the target can be detected and where it is not recognized to support@agisoft.com?

Also please specify, if all the targets that are not detected are very close to the image border.
Best regards,
Alexey Pasumansky,
Agisoft LLC

Yoann Courtois

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Re: Coded targets detection failed
« Reply #3 on: June 15, 2017, 04:42:23 PM »
Hi Alexey,

I gonna send you the following set of pictures:
- The 4 pictures liked above
- Other pictures which faced to the ground where targets where sometimes detected, sometimes not.

It's just a luck that this target is super close to the border of images sent, all the GSPs were distribute all along the area above which a global flight plan where handle.

Regards
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Yoann COURTOIS
R&D Engineer in photogrammetric process and mobile application
Lyon, FRANCE
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Alexey Pasumansky

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Re: Coded targets detection failed
« Reply #4 on: June 16, 2017, 03:20:39 PM »
Hello Yoann,

We have processed them using the coded targets detection method with additional output and it appears that some targets are not even recognized as a potentially valid targets. We assume that it is related to the rather small size of the central circular black point that should have area of at least 50-55 pixels. In your project the targets have the area of this point of a very close value, so some of them that ar slightly bigger are detected whereas others are not detected.
Best regards,
Alexey Pasumansky,
Agisoft LLC