Trouble with importing wilderness.net map data

DaveGoodrichDaveGoodrich Global Mapper UserPosts: 36Trusted User
edited November 2010 in Technical Support
I have been trying to open a shapefile downloaded from wilderness.net, which (surprise) shows wilderness area boundaries.

The file opens fine, but for some reason, does not appear to be properly located. The projection file included with the data contains the following:

PROJCS["WGS_1984_Web_Mercator",GEOGCS["GCS_WGS_1984_Major_Auxiliary_Sphere",DATUM["D_WGS_1984_Major_Auxiliary_Sphere",SPHEROID["WGS_1984_Major_Auxiliary_Sphere",6378137.0,0.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],UNIT["Meter",1.0]]

Global Mapper interprets this as "Mercator" and the parameters seem correct, but neverthess the data is shifted about 13 miles to the north of its true location in my area of interest (the Eastern Sierra of California). The shapefile is too big to email, but can be downloaded at and using the "Print/View/Download" dropdown box.

BTW, I am using GM10 at the moment, but hope to upgrade to 12 soon.

Thanks,
Dave

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2010
    Dave,

    The problem is the datum, it is probably coming in with the WGS84 datum, but it should really be the 'Google Maps' datum. If you go to the Projection tab of the Options dialog for the layer after loading it and change the datum to 'Google Maps' that should fix the problem.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
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