Monday, May 31, 2010

Create range thematics with Global Mapper

 It is not very obvious from the graphical user interface design and arrangement but it is quite possible to create thematic maps with Global Mapper; but the function is not as convenient as GeoMedia's or MapInfo's. I tried to use Global Mapper to create a similar range thematic map of average temperatures in the US as the sample GeoMedia dataset (shown below).

To create thematic maps in Global Mapper, do the following:

  1. Start up Global Mapper and display a polygon geometry data file e.g. States.shp.
  2. Press ALT+C.

    The Overlay Control Center dialog box appears.

  3. Select the layer in the list box and click Options.

    The Vector Options dialog box appears.

  4. Click the Area Styles tab.

  5. Toggle on Apply Styling Based on Attribute/Name Values.

    The Attribute/Name to Base Style On drop down list is activated.
  6. In the Attribute/Name to Base Style On field, choose a field e.g. AVETEMP.

    Note: In this example, we want to create a range thematic map based on the average temperature values in Fahrenheit from 20 degrees to 100 degrees. Each range is 10 degrees e.g. 60 ~ 69.99.
  7. Click New Value.

    The Select Area Style dialog box appears.

  8. In the Fill Pattern field, choose a value e.g. Solid Fill. Click the Fill Pattern Color.

    The Color dialog box appears.

  9. Choose a color. Click OK.

    The Enter Value for Style dialog box appears.

  10. Enter the value e.g. 60. Click OK.
  11. Repeat the previous steps 7 to 10 to create the ending range value e.g. 69.99.
  12. Repeat the previous steps 7 to 11 to create the next starting and ending range values e.g. 70 to 79.99.
  13. Toggle Interpolate Colors Between Numeric Values on.

    The Vector Options dialog box may look like this.

    Note: It is much easier to define thematic ranges in GeoMedia as it has a function to automatically classify the ranges based on the actual attribute values.
  14. Click OK.

    The range thematic map is created. Compare this with the sample GeoMedia thematic map above.

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