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Author Topic: Acceptable reprojection error?  (Read 566 times)

CoralNico

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Acceptable reprojection error?
« on: April 20, 2021, 05:29:20 PM »
I created a model using agisoft. The JPEG of the model is of acceptable quality and actually looks pretty good. I have had a hard time understanding what reprojection error is and therefore I'm unsure if the model is actually acceptable to use. I attached the report of two models. They both have reprojection errors one of 2 and one of 8. Are these acceptable? Is the model reliable?

I appreciate any help and also any links or files where I can read up on how to read the report and understand it to its fullest.

Thanks!

Paulo

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Re: Acceptable reprojection error?
« Reply #1 on: April 20, 2021, 07:57:13 PM »
Hi Coral,

I think the GoPro Hero8 Black camera uses a rolling shutter so you could try to select this option in the camera calibration window. And then redo Optimize cameras... Also, are u using some type of image stabilization during your shoots ? This is not recommended for photogrammetric processing. Your Camera modelization is quite off as image residuals in camear calibration section diagram are high (more than 1 pixel). You should also aim to get reprojection error less than 1 pixel or better 0.5 pix for good alignment....

Here is an example of good alignment with a Phantom3 12 Mpix camera with rolling shutter:

Number of images: 48                           Camera stations: 48
Flying altitude: 57.1 m                           Tie points: 32,106
Ground resolution: 2.12 cm/pix       Projections: 97,152       
Coverage area: 810 m²                          Reprojection error: 0.366 pix             
 
Attached is camera calibration residuals diagram.... note residuals are basically all very inferior to 1 pixel

Also there seems to be huge problem with your camera GPS locations. They are some kms off! (report 2) If this is underwater photography, then I would recommend to clear all camera reference coordinates before processing...

Maybe this can guide your work...
« Last Edit: April 21, 2021, 04:21:09 AM by Paulo »
Best Regards,

Paul Pelletier

CoralNico

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Re: Acceptable reprojection error?
« Reply #2 on: April 30, 2021, 03:37:51 AM »
Hi! Sorry for the late reply but thanks for the immense help. Sad that I keep getting such high reprojection errors. We are switching to DSLRs soon so Im hoping that may help. What exactly would a high reprojection error mean in regards to the model? II've had trouble understanding the meaning.