Annotating Google maps

Google maps are based on a Mercator projection of the world, it projects the world (a sphere) on a two-dimensional plane. The big advantage of a Mercator projection is that it creates a square, which is easily handled by a computer system as it allows access through Cartesian axes. The poles, however, are skewed (enlarged).

Prerequisites for geographical mapping:
  • a location or region. W.r.t. Google maps there are three ways of getting a location:
    • clicking on a map to add a pointer, message, or line
    • using x-y latitude-longitude system
    • specify a name (e.g. country or address)
  • optional: value related to location or region (e.g. temperature)
  • optional: description related to the location

Custom maps

  • When logged into a Google service, on http:/ go to my places and create/edit a map.
    • One can also link to custom icons, e.g. from
    • One can also create lines or area shapes. Both can be annotated like a marker
  • In Google spreadsheets
    • Data selection
      • If you have columns with an address or country, mark that one + another one containing the description for the infobox
      • If you have two separate columns with latitude and longitude, mark both in combination with a column for the description
    • Map generation
      • with location data selected go to insert > gadget > map to add markers to a map
      • with location data selected, go to insert > chart > map to color code country spaces, or to use bubbles depicting intensities
  • All maps can be shared with other Google users or embedded in e.g. a blog (make sure to make the map public first)

(Google maps works better in Google Chrome)

External walk-throughs

Example: map server locations of top 25 Dutch sites

Topic revision: r1 - 14 Mar 2012, ErikBorra
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