Global Mapper v26.0

Tree height canopy

crunchie
crunchie
in Elevation Data

Hi all

When obtaining a tree height canopy; which methodology is "more accurate":

1) DSM-DTM to give your canopy and extract elevation from the tree crown polygon OR

2) Use the crown polygon to extract LiDAR statistics from the LiDAR which has been converted to AGL heights

I have tried both and find some differences of up to 0.5m in some trees between the two. I am using young macadamia trees and the DSM is max binned to 10cm grids and DTM is binned to lowest 10cm grids.

I assume the differences are from the binning but any feedback would be appreciated.

Thanks

Answers

  • crunchie
    crunchie

    I figured out the differences - i was comparing agl heights from the lidar with the difference in DSM and DTM heights from the MSL LiDAR. When i create DSM and DTM grids from the AGL LiDAR the differences are much smaller and acceptable due to bin sizes.

  • dsmithdsmapping09
    dsmithdsmapping09

    Crunchie... have you anymore tips? Is the best workflow to produce DTM then DSM? Mind sharing a little more?

  • crunchie
    crunchie

    @dsmithdsmapping09 The best results i got were to 1) create DSM and DTM at height above ground (and not the native MSL heights) and 2) subtract the differences.

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