Point Cloud Ground Control Points heights Accuracy

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    Jakub Vanko RC

    Hi Robert,

    try turning off camera priors in the alignment settings and align again. This will ignore georeference from the cameras and only use GCPs. After this your GCP errors should be much lower and not around 110 m. 

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    Robert P Grain

    Hello 

     

    Thank you very much for the help. 

    I have just tried that but sadly it is still doing the same. I don't quite understand why it would do this either to show the z error of -100,000,

    When I create the GCP it shows correctly and then as soon as I add images then it starts to show wrong data so I assume I am bringing in the file correctly because it shows the correct location in the map.

    I think I must be so  close it is just this one last thing stopping me getting my results. I assume it must be possible ?

    Thank you 

     

    Rob Grain 

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    Jakub Vanko RC

    If you used the previous alignment you need to also set Force component rematch to True. It is in the Alignment settings, Advanced. It should definitely work with the Camera priors set to False this time. Please let me know if it worked for you.

    Jakub

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    Robert P Grain

    Hello Jakub

     

    I'm sorry for the delay in replying. I have now got the accuracy working well thanks to you, It works really well now I have turned the UAV GPS points off with the Exif =False and the Camera Priors = False.

     

    However I have found that to make it search through the images to help identify the Images that the Ground Control Points are in I run an alignment first with the GPS from the UAV and the Priors on = True, Then add the ground control points and then it helps identify the other images my points are then in and then I turn the Priors off and the Exif's to False and run the Alignment again, 

     

    I have gone from being a long way different from the Ground Survey Equipment to within 5% of them and so now I can tell clients that I am happy with the results I am getting is a true figure.

     

    Thank you very much for your help and support

    I love this software.

     

    Rob Grain 

     

     

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    Jakub Vanko RC

    Hello Robert,

    I am glad my answer helped you. You are doing it excatly how it should be done. To save time you can just do a draft alignment with the camera priors instead of full alignment. Then you approximately place your GCPs on the point cloud in the 3D view and refine their positions in images in the 2D view and do a full realignment again. Good luck with your future projects.

    Jakub

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