Using NaturalEarth as overlay

Capt PeteCapt Pete Global Mapper UserPosts: 6
edited December 2007 in Raster Data
I would like to use Natural Earth (or Natural Earth II) [http://www.shadedrelief.com/] as an overlay for some maps I'm creating. Unfortunately, the Natural Earth landcover extends into the ocean quite a distance. Is there a way I can restrict the raster overlay to just the land portion of my map?

I have vector shoreline for the map and saw the option in Control Center to make an area from selected but the vector area created doesn't follow the shoreline - it ends up as a rectangle. Any pointers greatly appreciated.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited December 2007
    How closely do you need to have your data file the shoreline? You could just manually draw an area that mimics the shoreline, then select that area, then go to the Options dialog for the raster layer from the control center and then go to the Feathering tab and select to feather to the selected area feature within some number of pixels. Then you'll get a smooth transition along the polygon border.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • Hans van der MaarelHans van der Maarel Global Mapper User Posts: 14
    edited December 2007
    A bit of a roundabout way:
    - Create a TIFF of your vector shoreline. Make sure it's exactly the same size and coverage as the Natural Earth image.
    - Open it up in Photoshop, use a single color to fill the sea
    - Select that color using the magic wand
    - Go Selection -> Save Selection
    - Open the Natural Earth image
    - Go Selection -> Load Selection
    - Delete everything inside the selection

    Hope this helps. Don't forget: this only works if the files are exactly the same size. Also, make sure you write TFW files for the georeference, as Photoshop will overwrite GeoTiff headers. Other image editors may have similar options.
  • Capt PeteCapt Pete Global Mapper User Posts: 6
    edited December 2007
    Thanks Hans - this looks like it will work.
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