When you create a thematic map in MapInfo Pro, the thematic shading is added to your map as a separate layer. It is drawn on top of the layer, from which it gets the raw data. Separating a thematic layer from its base layer provides you with several important options:
- Graduated symbol thematic maps do not require that your base layer contain point objects. Instead, graduated symbol objects are built regardless of the map object type. Therefore, even if your base layer contains region or line objects, you will still be able to create a graduated symbols map.
- You can have multiple thematic layers per base layer. In some cases, you do not have to add another base layer to the map to create another thematic layer. You can display more than one thematic layer at a time, as well as perform bivariate thematic mapping.
- You can turn the display on and off for a given thematic layer via the Layers or Explorer windows. The layer it is based on can continue to display. You can also set individual zoom layers on thematic maps.