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Author Topic: High error GPS markers  (Read 275 times)

Mouflan

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High error GPS markers
« on: June 30, 2020, 04:28:49 PM »
Hello all,

I have a question regarding some trouble with the error on my marker points in a project.
I’ve am trying to make a digital outcrop model base on drone photogrammetry and since the altitude measurements of the drone are not that accurate I used ground control points via a differential GPS system. However this provides me with two problems:

First of all the error of the markers/ground control points is very large (ranging from 2-122 meter) This seems to high to me however I cannot get it down. I've tried to optimize the cameras and re-align the cameras based on the markers.

Secondly the about half of markers keep floating above my point cloud. I think this might has to do with bad initial alignment however when I optimize my cameras based on the markers or re-align my with reference to the marker points the resulting point cloud this stays. A side effect of the re-alignment however is that some cliff faces/plains are placed in an angle or become ‘’multiple layered’’. So it seems that the GPS markers are wrongfully interfering with the alignment.

Attached is a screenshot of my reference window.

Did anyone had these kind of troubles before or has any suggestions? Thank you in advance!

Tim


Alexey Pasumansky

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Re: High error GPS markers
« Reply #1 on: July 01, 2020, 06:58:10 PM »
Hello Tim,

I suggest to check the errors shows after initial alignment without marker utilization: align cameras, place markers (or import from the XML), uncheck cameras in the Reference pane and press Update button on the pane's toolbar.

Then look at the markers that have highest errors in meters and pixels.
Best regards,
Alexey Pasumansky,
AgiSoft LLC