Monday, September 26, 2011

Create a thematic map with gvSIG

Creating thematic maps based on one or more attribute fields of a geographical feature is a fairly typical GIS task. The free and open source software gvSIG has the tools to quickly generate a thematic map of a geographical layer. The example below shows the procedure to color the thematic map according to unique attribute field values.

  1.  Open up gvSIG OADE and display a polygon layer e.g. States.shp.

  2. In the legend, press a mouse right click on the States.shp layer.

    A pop up menu appears.
  3. Choose Properties.

    The Layer properties dialog box appears.
  4. Select the Symbology tab.

  5. Expand the Categories tree node. Choose Unique values.
  6. In the Classification field, choose the field to style with e.g. STATE_NAME.
  7. In the Color ramp field, choose a suitable color table.
  8. Click Add All.

    The colors are assigned to each unique field value.
  9. Click OK.

    The thematic map is generated.

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