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[mkgmap-dev] DEM bug at 50°N

From Bernhard Hiller bhil at gmx.de on Tue Apr 10 10:28:14 BST 2018

Hi Gerd,

an example of a tile with the bug is 43100115, but many more tiles show 
the bug, like 43100096 along Lech river near Landsberg.

In contrast, 43100105 looks OK south of 48°N (south part of Freiburg 
town, Schauinsland mountain), but wrong in the northern suburbs of 
That is, a tile can have both correct and defective DEM values.
48N is also the border between L32 and M32 zip files with DEM data.

My current impression is that everything north of 48° is wrong, take 
also a look at the relief at the Oder river near the German-Polish 
border. Places in southern Bavaria and Baden-Württemberg look OK.

Do we have some software for visualising where to find which tile? 
QLandkarte GT shows tile borders, but no information re its number.

Kind regards,

Am 09.04.2018 um 07:26 schrieb Gerd Petermann:
> Hi Bernhard,
> might be a special case.
> Please post the split-file (areas.list) and the tile number that causes problems.
> 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=eas.poly ^
>       --dem=EMPATH% ^
>       --dem-dists314,4000,6000,8000,10000,15000,20000,30000 ^
> areas.poly were created by splitter in the step before,
> DEMPATH=\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
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev

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