gmp2shp: data lost?
hgleixner
Global Mapper UserTrusted User
Hello,
I would like to generate a hugh amount of contour lines using the option to write directly into a gmp file. Importing that file and converting it to shape looks as there would be some data lost. See the different metadata:
Metadata of the gmp file:
FILENAME=D:\Arbeit_22032013\Felszeichnungsversuche\DGM25_test_100m_HL.gmp
DESCRIPTION=DGM25_test_100m_HL
AREA COUNT=0
LINE COUNT=15892
LINE VERTEX COUNT=1843580
POINT COUNT=0
UPPER LEFT X=4286180.000
UPPER LEFT Y=5604756.500
LOWER RIGHT X=4635600.000
LOWER RIGHT Y=5238293.500
WEST LONGITUDE=8° 58' 59.0944" E
NORTH LATITUDE=50° 34' 46.9516" N
EAST LONGITUDE=13° 54' 50.7915" E
SOUTH LATITUDE=47° 14' 57.2143" N
PROJ_DESC=Gauss Krueger (3 degree zones) / POTSDAM / meters
PROJ_DATUM=POTSDAM/DHDN (GERMANY)
PROJ_UNITS=meters
EPSG_CODE=31468
COVERED AREA=128050 sq km
Metadata of th shape file:
FILENAME=D:\Arbeit_22032013\Felszeichnungsversuche\DGM25_test_100m_HL.shp
DESCRIPTION=DGM25_test_100m_HL.shp
AREA COUNT=0
LINE COUNT=15647
LINE VERTEX COUNT=1843090
POINT COUNT=0
UPPER LEFT X=4286180.000
UPPER LEFT Y=5604756.500
LOWER RIGHT X=4635600.000
LOWER RIGHT Y=5238293.500
WEST LONGITUDE=8° 58' 59.0944" E
NORTH LATITUDE=50° 34' 46.9516" N
EAST LONGITUDE=13° 54' 50.7915" E
SOUTH LATITUDE=47° 14' 57.2143" N
PROJ_DESC=Gauss Krueger (3 degree zones) / POTSDAM / meters
PROJ_DATUM=POTSDAM/DHDN (GERMANY)
PROJ_UNITS=meters
EPSG_CODE=31468
COVERED AREA=128050 sq km
Why that difference (GM14.2 (b061313) 64 bit)?
Note: If I don't write directly into a gmp file (possible only in smaller cases) I get 15892 lines too, after converting that into shp there are 15650 lines (3 more as above)
Regards Henry
I would like to generate a hugh amount of contour lines using the option to write directly into a gmp file. Importing that file and converting it to shape looks as there would be some data lost. See the different metadata:
Metadata of the gmp file:
FILENAME=D:\Arbeit_22032013\Felszeichnungsversuche\DGM25_test_100m_HL.gmp
DESCRIPTION=DGM25_test_100m_HL
AREA COUNT=0
LINE COUNT=15892
LINE VERTEX COUNT=1843580
POINT COUNT=0
UPPER LEFT X=4286180.000
UPPER LEFT Y=5604756.500
LOWER RIGHT X=4635600.000
LOWER RIGHT Y=5238293.500
WEST LONGITUDE=8° 58' 59.0944" E
NORTH LATITUDE=50° 34' 46.9516" N
EAST LONGITUDE=13° 54' 50.7915" E
SOUTH LATITUDE=47° 14' 57.2143" N
PROJ_DESC=Gauss Krueger (3 degree zones) / POTSDAM / meters
PROJ_DATUM=POTSDAM/DHDN (GERMANY)
PROJ_UNITS=meters
EPSG_CODE=31468
COVERED AREA=128050 sq km
Metadata of th shape file:
FILENAME=D:\Arbeit_22032013\Felszeichnungsversuche\DGM25_test_100m_HL.shp
DESCRIPTION=DGM25_test_100m_HL.shp
AREA COUNT=0
LINE COUNT=15647
LINE VERTEX COUNT=1843090
POINT COUNT=0
UPPER LEFT X=4286180.000
UPPER LEFT Y=5604756.500
LOWER RIGHT X=4635600.000
LOWER RIGHT Y=5238293.500
WEST LONGITUDE=8° 58' 59.0944" E
NORTH LATITUDE=50° 34' 46.9516" N
EAST LONGITUDE=13° 54' 50.7915" E
SOUTH LATITUDE=47° 14' 57.2143" N
PROJ_DESC=Gauss Krueger (3 degree zones) / POTSDAM / meters
PROJ_DATUM=POTSDAM/DHDN (GERMANY)
PROJ_UNITS=meters
EPSG_CODE=31468
COVERED AREA=128050 sq km
Why that difference (GM14.2 (b061313) 64 bit)?
Note: If I don't write directly into a gmp file (possible only in smaller cases) I get 15892 lines too, after converting that into shp there are 15650 lines (3 more as above)
Regards Henry
Comments
-
Henry,
There are probably some line segments that are empty (i.e. just 1 point or all points at the same location) and those are discarded on export to Shapefiles. The GMP export just exports them as-is and doesn't discard the degenerate lines. They are discarded for Shapefile export since some applications will crash when encountering lines like that. Since GMP is only read by Global Mapper there is no such issue there.
Thanks,
Mike
Global Mapper Guru
geohelp@bluemarblegeo.com
Blue Marble Geographics for Coordinate Conversion, Image Reprojection and Vector Translation
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