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MapInfo Monday: Creating a Cartographic Legend

  • 1.  MapInfo Monday: Creating a Cartographic Legend

    Employee
    Posted 05-12-2025 03:38

    MapInfo Pro supports two types of legends: Thematic and Cartographic.

    The thematic legend is created for a thematic layer. For a thematic layer, you assign a style to your map objects based on attribute information for these objects. In this way, the style of the map objects is tightly linked to the attribute information and will also reflect any changes in the attribute information. You can read more about thematic maps in this article: MapInfo Monday: Getting Started with Thematic Map.

    MapInfo Pro also allows you to have hardcoded styles assigned to the objects in your tables. This can mean the styles aren't linked to the attribute information in your table. I would always recommend basing your style on your attributes in some way or form. This will make it easier to work with your data. To create a legend for hardcoded styles in your table, use the cartographic legend.

    In this article, I will give you an introduction to the cartographic legend.

    Happy #MapInfoMonday!

    Creating a Cartographic Legend

    In the map below, you can see polylines representing a connected walking route we are working on in my local neighborhood.

    The style of the polylines represents the type of road or path. To make that clearer, I want to create a legend for the map.

    From the Add To Map dropdown on the Map tab, I select the Legend control.
    This will allow me to add legends for one or more vector layers in my map. I will be taken through a few dialogs to configure the legends.
    First, in the Create Legend - Choose Layer dialog, I'm asked to select the layers I want to create legends for.
    MapInfo Pro will only list the layers for which you can create a legend. It will not list raster layers and layers that already have a cartographic legend.
    I keep the layer that already has been added to the right list.
    In the Create Legend - Legend Default Properties dialog, you can change the default properties of new legends. These settings can also be set as a preference so that you start in the most typical way.
    I keep the values as they are and click on the Next > button to continue.
    In the final dialog, the Create Legend - Frame Properties dialog, you configure the behavior of the individual legend frames you are adding for your map.
    I'm working with a local native table, so I'll skip the map catalog options in this article.
    You can specify a title and a subtitle for the legend frame. It can be advisable to add a title if you have many layers.
    Next, you need to control how to group the elements in your legend. You can base this on the unique map styles or on unique values in a column.
    If you use the unique map styles, you will get a complete list of all the various styles you have used. This can also help identify potential issues with styles. Maybe a few styles are similar but not quite identical. 
    If you use the unique values from a column, the records will get grouped by these values, and the first style for each value will appear in the legend. This will not highlight issues with similar but not identical styles.
    For Label styles with you can select the default behaviour, which will list the layer name or object type for each style. Or you can select a column with descriptions aligned with the styles. You can see that I have picked the column PathType, which contains a short description of the surface for the foot paths.
    If you are happy with your configuration, you can save this to the metadata section of the table using the Save frame settings to Metadata button. This will remember your legend settings for this table in the tab file and allow you next time to click on the Finish button in the first dialog.
    If possible, I would always recommend using a thematic map. But there are times when hardcoded styles are preferred.
    I also want to highlight two tools in the WindowHelper tool for MapInfo Pro that allow you to switch from hardcoded styles to a theme and from a theme to hardcoded styles.
    The feature Static Theme in the WindowHelper tool allows you to create a thematic layer based on the current hardcoded styles and a column that you select. This lets you switch to a thematic layer using the current styles from your spatial objects. 
    Save Styles to Table, on the other hand, allows you to assign hardcoded styles to your objects based on values and styles from a thematic layer.


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    Peter Horsbøll Møller
    Principal Presales Consultant | Distinguished Engineer
    Precisely | Trust in Data
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