Datum Parameters
PatG
Global Mapper UserTrusted User
I have a Local datum setup and saved based on the GRS80 ellipsoid with a TM projection.
The parameters for GRS80 are:
Semi Major = 6378137.0
inv flattening = 298.257222101
These are stated in the GlobalMapper ellipsoid file (ellipsoid.csv)
However if I save my datum to a file it states the following for GRS80
SPHEROID["GRS 1980",6378137,298.2572220960423]
Why the discrepency and how much will it affect my translations?
Cheers for any info....
The parameters for GRS80 are:
Semi Major = 6378137.0
inv flattening = 298.257222101
These are stated in the GlobalMapper ellipsoid file (ellipsoid.csv)
However if I save my datum to a file it states the following for GRS80
SPHEROID["GRS 1980",6378137,298.2572220960423]
Why the discrepency and how much will it affect my translations?
Cheers for any info....
Comments
-
Pat,
The ellipsoids.csv file does not contain the ellipsoid definitions used by Global Mapper, it is a data file used by one of our 3rd party import libraries. The difference in the flattening value is extremely small and would result in differences less than 1 mm in size.
Let me know if I can be of further assistance.
Thanks,
Mike
Global Mapper Support
support@globalmapper.com
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