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Finding Central Meridian for Mercator chart

anticus Global Mapper User
edited February 2009 in Projection Questions
I need to georeference a scanned chart using the standard Mercator projection (not UTM).
How do I determine the Central Meridian to use for the procedure if it is not specified on the map ? What about Scale Factor, Origin Latitude and False Easting and Northing ?

Can I georef in UTM and reproject to Mercator ?



  • global_mapper
    global_mapper Administrator
    edited February 2009
    Typically the Mercator projection is used with 0 for all parameters. If you are just entering lat/lon values and having Global Mapper automatically convert to Mercator, that is what I would use. If you are entering Mercator values directly off the map, you would need to check with the producer of the map to be sure, but I would try all 0 parameters first to see if it works.

    Let me know if I can be of further assistance.


    Global Mapper Support
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