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exporting height above ground in las format

asilvaasilva Global Mapper UserPosts: 4
edited January 2015 in Elevation Data
When perform a selection in a LiDAR point, in the feature information appears height above ground.

I need to export this attribute in las format. Is it possible?

Thanks.

Ariel Silva

Comments

  • stihlstihl Global Mapper User Posts: 52Trusted User
    edited January 2015
    Hi Ariel,

    I'm a bit confused as to what you're trying to achieve.

    You have a LIDAR (LAS) point cloud and you made a selection in that point cloud of an area you want to export. However with the export you want to use a specific attribute for height instead of the default Z value, is that correct?
  • asilvaasilva Global Mapper User Posts: 4
    edited January 2015
    Exactly, I've mentioned a point selection only like a example.

    But, the question is related with obtain height above ground from a cloud point in las format.
  • stihlstihl Global Mapper User Posts: 52Trusted User
    edited January 2015
    Obtain height from the point cloud at a certain points?
  • asilvaasilva Global Mapper User Posts: 4
    edited January 2015
    Excuse me, I didn't explain so well...

    This is las file with color by elevation:

    elevacion.PNG
    This is the same las file with color by height above ground:
    hag.PNG

    The issue is that I can't export this last representation.

    Any idea?
  • stihlstihl Global Mapper User Posts: 52Trusted User
    edited January 2015
    Hi Asilva,

    I now know what you meant, thanks for elaborating.

    I just tested to see if I could do what you're trying to do. Which GM version are you on?

    What I did was load a point cloud I had, put the view from 'Color Lidar by RGB/Elev' to 'Color Lidar by height over ground'. I assume this is what you did as well?

    Then I went to File > Export > Vector > Las format > in the LAS export dialog check the box that says 'Save height Above ground instead of elevation'.

    Then I exported the file, closed GM and open the exported file. If I then put the view back to 'Color Lidar by RGB/Elev' I see a height scale bar with 0 meters at the bottom in blue. And in the LAS file I'm seeing the lowest points as blue and the highest as red relative to eachother.

    Is this what you're trying to achieve?
  • asilvaasilva Global Mapper User Posts: 4
    edited January 2015
    Thanks! It works!
  • stihlstihl Global Mapper User Posts: 52Trusted User
    edited January 2015
    Good to hear :-)
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