According to the DEM in the map, the Rhine river some 3 km away from my home is at an elevation of some 2600 m asl. I do not live in the Swiss alps, but some 50km west of Frankfurt, just north of 50°N... The correct elevation is about 80m. Near Bingen (just south of 50°N), the Rhine is at an elevation of ~500m, somewhere between Assmannshausen and Lorch it ascends suddenly and very steeply to almost 3000m. In Cologne still at 500 m asl. South of 48°N, the data seem OK; but in the north, I did not find reasonable values - the Elbe in Hamburg above 1000m asl.

I exclude a problem in the DEM data: before creating the map of Germany and Czechia, I tested with Hessen only. And then, the DEM values looked reasonable.

I use mkgmap 4143. The command includes parameters for DEM:
    --dem-poly=areas.poly ^
    --dem=%DEMPATH% ^
    --dem-dists=3314,4000,6000,8000,10000,15000,20000,30000 ^
areas.poly were created by splitter in the step before,
SET DEMPATH=E:\Maps\Development\SRTM\,E:\Maps\Development\SRTM\,E:\Maps\Development\SRTM\,E:\Maps\Development\SRTM\,E:\Maps\Development\SRTM\,E:\Maps\Development\SRTM\ contains DEM data from (while testing with Hessen, %DEMPATH% was E:\Maps\Development\SRTM\ only which contains data from N48E006 to N51E011).

Or is it a matter of file size? The largest *.img file has 131256kB.

Kind regards,
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