Coordinate convertor problem
rbr
Global Mapper User
Hi,
I have converted, with the global mapper coordinate convertor, the following value between geo( lat-lon) wgs84 datum to
mercator kkj datum:
27.07400521861
61.6390009939 in geo( lat-lon) wgs84
converted to mercator /kkj is
3014341.442
8736525.795
This conversion seems to be incorrect. In fact, using the conversion system provided by the Finnish institute at this link:
Citizen’s MapSite - National Land Survey of Finland
I have a different result.
Could you help me understand why?
I have converted, with the global mapper coordinate convertor, the following value between geo( lat-lon) wgs84 datum to
mercator kkj datum:
27.07400521861
61.6390009939 in geo( lat-lon) wgs84
converted to mercator /kkj is
3014341.442
8736525.795
This conversion seems to be incorrect. In fact, using the conversion system provided by the Finnish institute at this link:
Citizen’s MapSite - National Land Survey of Finland
I have a different result.
Could you help me understand why?
Comments
-
The Finnish Grid system is not a Mercator projection but a Transverse Mercator with the following parameters:
Transverse Mercator
DATUM: KKJ (FINNISH GRID)
UNIT: meters
CENTRAL MERIDIAN SCALE FACTOR: 1
CENTRAL MERIDIAN: 27.000000
ORIGIN LATITUDE: 0.000000
FALSE EASTING (m): 3500000
If you use that you should get results that agree with the official conversion site.
Note that I did take a look at the datum conversion and find slightly better parameters than were used that should give you sub-meter accuracy in the conversion. I have placed a new build at http://www.globalmapper.com/global_mapper10.zip with the change for you to try. Simply download that file and extract the contents into your existing v10.xx installation folder to give it a try.
Let me know if I can be of further assistance.
Thanks,
Mike
Global Mapper Support
support@globalmapper.com -
Thanks,
everything is fine now.
Best regards.
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