The following steps show how to perform a vertical datum correction with the reprojection filter of PDAL:
- Optional. Download an appropriate geoid file e.g. egm08_25.gtx for EGM2008 from http://download.osgeo.org/proj/vdatum/ and place it in a folder e.g. D:\Temp\PDAL\
- Open up the OSGeo4W Shell.
- In the Command Prompt, type in the following command:
D:\> pdal translate -i input.las -o output.laz reprojection --filters.reprojection.in_srs="EPSG:32610+4326" --filters.reprojection.out_srs="+init=EPSG:32610 +geoidgrids=D:/Temp/PDAL/egm08_25.gtx" --writers.las.compression="true" --writers.las.a_srs="EPSG:32610+3855" -v 4
where
--filters.reprojection.in_srs specifies the source coordinate reference system EPSG:32610 or UTM 10 North and the source vertical datum of EPSG:4326 which is the WGS84 Ellipsoid
--filters.reprojection.out_srs specifies the destination coordinate reference system EPSG:32610 (the same as the input) and the EGM2008 grid file to apply
--writers.las.a_srs tells PDAL to write the destination coordinate reference system of EPSG:32610 and vertical datum EPSG:3855 (which is the EGM2008 datum) to the output file. - Press RETURN.
Processing messages appear. The input las file is reprojected to the EGM2008 vertical datum. - Optional. Overlay the input and output LAS files in a viewer and observe the vertical offset in a profile as shown below.
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