[mkgmap-dev] DEM bug at 50°N

Wed Apr 11 08:49:03 BST 2018

Hi Bernhard,

it turned out to be a stupid error in my code, see 
http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4154
Please use r4154 (overlaps branch) or r4155 from trunk.

I did not notice this because I never used the zipped files from viewfinder because their names (e.g. m32.zip) give
so little information about the content :-(

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen at hotmail.com>
Gesendet: Mittwoch, 11. April 2018 09:23:00
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] DEM bug at 50°N

Hi Bernhard,

I think the problem is that the zip files are not in one of the expected formats. You should see better results if you unzip the files.
I'll try to add support for this format now.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Bernhard Hiller <bhil at gmx.de>
Gesendet: Sonntag, 8. April 2018 20:40:23
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: [mkgmap-dev] DEM bug at 50°N

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\L32.zip,E:\Maps\Development\SRTM\M32.zip,E:\Maps\Development\SRTM\N32.zip,E:\Maps\Development\SRTM\L33.zip,E:\Maps\Development\SRTM\M33.zip,E:\Maps\Development\SRTM\N33.zip
contains DEM data from
http://www.viewfinderpanoramas.org/Coverage%20map%20viewfinderpanoramas_org3.htm
(while testing with Hessen, %DEMPATH% was
E:\Maps\Development\SRTM\M32.zip only which contains data from N48E006
to N51E011).

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

Kind regards,
Bernhard
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