Re-Rectify Vector Data

anabranchanabranch Global Mapper UserPosts: 14Trusted User
edited April 2010 in Technical Support
I have a series of 20 bathymetric contour lines exported from an AutoCAD file. Each file has a line at the base to which I have 3 supposed control points. When I rectify this data with the points it gets to the ballpark but does not match the shape of the river (data from 2000 compared to a Landsat from 2000). See attached image.

I have rectified the file corresponding to the margin data (what is the example) so that it matches the banks of the river. I saved the roughly 20 ground control points from the rectification. I hoped that I would be able to load another vector dataset, choose re-rectify and apply these control points to the file so that it warps to match the margin data. However, when I load the control points in the rectification dialog and choose OK when I come back to the main program there has been no change. I even took the original margin data and tried to use the control points to get it to match what I had done earlier but no luck.

Is what I am trying possible? Am I just a doofus (probable)?

Any help would be greatly appreciated,



  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited April 2010

    Rectifying vector layers can get a bit tricky because when you apply a rectification to vector data the original coordinates are transformed and become a new set of original coordinates, so applying the same control points to that file again will have a different starting point than the original. This is different than raster layers which have a fixed pixel space coordinate system that doesn't change.

    So with vector data you need to make sure when applying control point that you are always starting with the original un-transformed vector coordinates and not applying multiple transformations on top of each other.

    Let me know if I can be of further assistance.
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