las2las - lidar transformation using NTV2

[Antoine Billault]

Dear All,
We often transform raster file into different datum (recent datum to old datum), and to maintain data accuracy we use NTV2 file which is an interpolation grid that convert source file into destination file.
Using OSGEO4W the command looks like that

gdalwarp -s_srs EPSG:3945 -t_srs "+init=IGNF:LAMB3 +wktext" -co COMPRESS=LZW -r cubic -srcnodata 0 -dstnodata NULL out_L3S.tif

Indeed GDAL support NTV2 file . Here it is explicitely said by "+init=IGNF:LAMB3 +wktext"

Now I am thinking how I can apply that NTV2 in order to make the same transformation between 2 LAS/LAZ files ...?
It seems that las2las supports GDAL transformation.

Can I call that interpolation grid in the same way ? something like

las2las -i source.laz -o out.las +init=IGNF:LAMB3 +wktext"

Thanks for your help.

Antoine

[Martin Isenburg]

Hello Antoine,

In order to keep LAStools a "light-weight" standalone toolset I decided early on not to include the entire proj4 functionality and grids. However, I think that the "other las2las" from libLAS that shot-off LASlib in 2007 there is a similar las2las tool with the functionality you are looking for and even similar command lines than the ones you describe. Find the las2las usage description and the download on http://www.liblas.org 

Regards,

Martin @rapidlasso

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[Howard Butler]

Antoine,

I would use PDAL via OSGeo4W64, not libLAS, and you should have all the Proj.4 + GDAL vertical+horizontal datum transformation capability you need.

Howard

[Antoine Billault]

Hello all,
here is the solution, thanks to PDAL
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FOR %Q IN (C:\xxxxxx\OUT-LAZ\*.laz) DO pdal translate  "%Q" "%~dpnQ_L3S.laz" -f filters.reprojection --filters.reprojection.in_srs="EPSG:2154" --filters.reprojection.out_srs="+init=IGNF:LAMB2 +wktext"
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antoine