Tie drone survey into GCP in Global Mapper

I have a number of drone surveys that are great in terms of resolution and relative accuracy, but they lack precision XYZ they are off from global position by 10feet more or less.  I have the surveys in Orthomosaic (JPG), point cloud XYZ or LAS, DEM, and contours DXF

If I shoot some Ground Control Points (GCP) on features which are identifiable on the orthomosaic, I could rectify the orthomosaic, but is there a way to rectify the point cloud, DEM, and Contours to the new GCPs?  

Global Mapper always has a way.  Thanks for the help

Answers

  • Yes it is all done the same way. Either use Rectify and go through it. Or in Control Center, right click the item, select RECTIFY - or select SHIFT. SHIFT is for horizontal move when you already know what the move is.

    Get the coordinate of a photo identifiable point, then of the control point. Compute the move. Put that in using the SHIFT function. Be careful as it will ask for bearing - but really is asking for azimuth (which is not same thing.)

    You can do this for an ortho raster - and same for point cloud. Might need the Lidar addon though - not sure. Probably do not need it for this. I would just re-make the DEM after shifting the point cloud. But you could likely shift a dem as well - same way.

    I assume you just want to move to a known point - and then let your raster remain at the same internal integrity it already had. SO you will be looking at its precision. If you want to have each control point warp locally and you miss in a different distance and direction at each control ... that is a different matter and too complicated for this post. I would suggest remake the raster from scratch using the control points in the process - using whatever software you typically use - pix4d or photoscan or whatever. If you did not use it then, too late now to fix the raster in GM. If not sure what this all means ... you probably well over your head in photogrammetry.

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