Global Mapper v25.0

Detecting and deleting duplicate areas

Hunter Geophysics
Hunter Geophysics Global Mapper UserTrusted User
Hello.

As per the attached screenshot, I have created two points (one at either end) of 158 rectangular areas. As shown in the control centre, though, there are only 312 points.

As there are 158 areas, and two points per area, there should be (158*2=316) 316 points.

As you can also seen in the screenshot, though, every area that is visible has the two points.

So I suspect there two of the areas have been duplicated somehow.

Is there a way of easily detecting which areas have been duplicated, and then deleting them?

(I'm still on GM v16.2, by the way... I understand the solution may require an upgrade.)

Thanks in advance.
David

Answers

  • Ice Age Mark
    Ice Age Mark Global Mapper User Trusted User
    Hello again David,

    There is a "find features with duplicate attributes" function under the Search menu. If any attributes that can be automatically created by GM for your rectangles (like area or perimeter length or coordinates), or ones you could think up and add (rotation angle?), were unique; you could possibly use that function to find your duplicates.

    Hope that works.

    Best regards,

    Mark
  • Hunter Geophysics
    Hunter Geophysics Global Mapper User Trusted User
    Thanks, Mark. How would I get GM to automatically create such attributes? Or would they be created when the areas is created?

    (the areas I have now don't seem to have any attributes...)
  • Ice Age Mark
    Ice Age Mark Global Mapper User Trusted User
    Hello David,

    I created half a dozen random rectangles, then used copy and paste to duplicate two of them.  I was then able to use this method to find the duplicates:

    Select ALL of the rectangles (by whatever way works best for you), right click, and go to Advanced Feature Creation.  From that menu choose to "Create point at the centroid of each area".

    The points will be selected when created, so move them to a seperate layer for easy selection and later disposal.  (Right click, edit, etc.)

    Select ALL of the new centroid points (by whatever way works best for you), right click,  and go to Search.  From that menu choose "Find all points within ??? meters..."  Put in a very small distance, and GM should find the duplicate centroids and highlight them with blue circles.  These are also the rectangles that are duplicates.  (First you will get an option to save the duplicates as a CSV file, just cancel that and you will see the duplicate centroids circled in blue.  Escape unselects the duplicates.)

    That should work for you.  If you have problems, let me know.

    Once again, cool and fascinating surveying/geophysics niche !

    Mark