How to convert DEM with vertical DATUM DHHN2016 height EPSG:7837 to EGM96 height - EPSG:5773?

Question

There is a lidar data source of digital elevation model of Germany.

1. The spec of the lidar data is:

• Horizontal CRS: EPSG 25832
• Vertical DATUM: EPSG 7837

2. I have anther DEM whose vertical datum is WGS84 Earth Gravitational Model (EGM 96) geoid.

How can I transform my DEM to make it have the same vertical datum as EPSG:7837. I don't have ground control points. Is it possible to do the transformation without GCP?

Answer 1

Using gdal you can add the vertical datum with -s_scs EPSG:25832+7837:

gdalwarp -s_srs EPSG:25832+7837 -t_srs "+proj=longlat +datum=WGS84 +no_defs +geoidgrids=egm96_15.gtx" input.tif output.tif

You can download the grid from osgeo and copy the file to ../share/proj/ withing your gdal/qgis path.