Creating a Thematic Map
In the previous sections, we learned how to assign and edit the attributes of vector features. In this section, we will use this attribute information as the basis for applying colors to the corresponding polygons. Often referred to as thematic mapping, this process is fundamental to the analysis of spatial patterns in the data.
Before undertaking a hands-on exercise in thematic mapping, it is worthwhile considering some of the other ways in which distinct colors can be applied to vector features.
- When digitizing a point, line, or polygon, or after opening the Edit dialog box for a selected feature, the visual characteristics for that feature can be assigned by selecting a Feature Type
- Similarly, the Modify Feature Info dialog box offers the option to override the default feature style and manually assign the colors or style for a selected feature
- In the Layer Options dialog box, accessed from the Control Center, the visual representation for all features in the corresponding layer can be collectively modified
The default style for each Feature Type can be modified in the Styles section of the Configuration dialog box
Similar to the final option in the preceding bulleted list, the process of assigning colors to reflect the contents of a specified attribute field is initiated in the Options dialog for the selected layer.
Follow along with this video as the instructor creates a thematic map using the parcels data from the previous lesson. To prepare, unload any currently loaded layers (Ctrl+U) and load a new version of the Black Mountain Parcels shapefile from here:
*Intro to Global MapperDataParcelsBlack Mountain Parcels.shp.
To quickly edit the display of the on-screen legend, right-click on the legend and choose Map Legend Options…
Summary
- Global Mapper offers numerous options for adjusting the display of selected points, lines, and polygons, or of an entire layer
- The process of creating a thematic map involves the selection of the required attribute within a layer, the determination of the corresponding attribute values, and the manual or automatic assignment of the subsequent style characteristics
- Thematic mapping exposes the inherent spatial patterns within a vector layer, providing the basis for visual analysis
- Click here for more information