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:/maps.google.com go to my places and create/edit a map.
  • One can also link to custom icons, e.g. from http://thenounproject.com
  • 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

• Make map with markers and text balloons from spreadsheet: http://gmaps-samples.googlecode.com/svn/trunk/spreadsheetsmapwizard/makecustommap.htm
• Elaborate and clear walk-through of how to use google spreadsheets to generate custom Google maps as well as Google earth maps. https://multimedia.journalism.berkeley.edu/tutorials/using-spreadsheet-data/
  • Create Google earth maps, starting from a spreadsheet. Includes how to create a guided and narrated tour. http://earth.google.com/outreach/tutorial_spreadsheet.html
• Copy-paste tabular data in https://www.batchgeo.com/ in order to make Google maps with markers and balloons
• Turn spreadsheets into heat maps: http://www.openheatmap.com/ Make sure to have column names which openheatmap understands.
• Many Eyes' world maps also provide interactivity

Example: map server locations of top 25 Dutch sites

• Retrieve top 25 URLs from http://www.alexa.com/topsites/countries/NL make sure to retain the order
• Get geographic location of the main IP-address of above URLs in https://lab.digitalmethods.net/~erik/tools/beta/geoIP/
• Copy-paste results in a (Google) spreadsheet, like https://docs.google.com/spreadsheet/ccc?key=0Am8EIPTuGoQWdFZTNFdJRFVPdTlTTmsyWXZJYkxKa2c#gid=0
  • Add rank and quintile information
• Visualize the data. Go to https://batchgeo.com/ and copy-paste the data into the main input field
  • Click 'validate and set options'
    • Verify options > 'group by' should be set to 'quintile'
    • click advanced > check 'Enable clustering for high density markers'
  • click 'Make Google Map'
  • your map now shows pie charts, with the colors depicting how many hosts from a particular quintile are available in a country