Working with Prism Maps - MapInfo_Pro - 2023

Prism maps offer another way to create a three-dimensional view of your map. In a Prism Map, the height of the geography is raised according to a specified column value from your table or a derived value from an expression-the greater the value, the higher the height of the geography. Each geography becomes a prism, allowing you to compare data values of objects relative to each other according to the height of each prism.

Prism maps are created using region layers. Other closed objects such as rectangles, ellipses, and rounded rectangles are also included in the Prism Map, as well as the region portion of Collection objects. Point objects are not included in the Prism Map.

The prism effect does not interfere with the display of other components in a Map window, including other map layers, themes, or labels. When the Prism Map is created, the image from the original Map window is "pasted" on the resulting 3D objects.

The commands for Prism maps are the same as those for 3DMaps. You can control the view of the map, create a duplicate view, and set the map's point of view, enabling you to choose the angle that will best emphasize the prism effect of the raised geographies.

Creating a Prism Map

You can create a Prism Map, which displays the base geometry to the height of a corresponding row value. A Prism Map displays the magnitude of certain mapped values with respect to others. You can combine a Prism Map with a color thematic map to display two attributes onto one map to correlate and compare various values.

To create a Prism Map:

1. Click the Map window to make it active and ensure that the Map window contains a region layer.
2. On the HOME tab, in the Windows group, click New Document, and click Prism Map from the list, to open the Create Prism Map dialog box.
3. In the Choose Layer and Column group, choose the layer to map, and choose a column value.

   Only numeric columns from the layer you chose display in the dialog box.

4. From the Column drop-down list, choose Expression to use a character column.

   The Expression dialog box opens.

5. Create an expression.

   Select the character column you want to use, and use the Val() function to convert a character string to a numeric value. This function returns zero for any character string that has no numeric meaning.

6. In the Appearance group, select the Background color.

   This color is used for the window's background.

7. Select the Light color.

   This color is the lighting for your map. It acts as a "cover" to the camera lens as it views the map.

8. In the Camera group, choose the camera's position and orientation.

   The Horizontal Angle measures the rotation of the map around the center point of the grid. This value can range from 0-360 degrees. The Vertical Angle measures the rotation in elevation from the start point directly over the map. This value ranges from 0-90 degrees.

9. Click OK.

The Prism Map displays in your Map window.

Viewing the Entire Prism Map

If you zoom or pan the Prism Map and the map becomes out of view. Use the View Entire Layer command to recenter the Prism map in the window.

To display an entire Prism Map, right-click and choose View Entire Layer.

Viewing a Previous Prism Map

By using Previous View repeatedly, you can toggle back and forth between two views of your map.

To return to the previous view of a Prism Map, right-click and choose Previous View.

If you find yourself doing this often with a particular map, you might want to create two maps of the same table, each with a different view. Then you can view the two simultaneously.

Bivariate Prism Maps

Because prism maps preserve the display of other map elements, including themes, you can easily add a second theme to your Prism Map, such as ranges or individual values, to create a bivariate map. For more about Bivariate maps in general, see About Bivariate Thematic Mapping.

Prism Map and Browser Editing

If you change a row value of an object in a Prism Map or edit an object directly in a Map window, the Prism Map will reflect these changes. For example, if you change a data value that was used directly in a Prism Map, or as part of an expression that was used to calculate a value, the prism height of the corresponding objects will change to reflect the new value. This includes single row changes and column updates.

When you move objects in a Prism Map, the Prism map object that is based on the original object will also move. When you add objects to the Prism Map, they will display flat because data values for new objects are initially set as zero.

Sometimes an object in a Prism Map displays the incorrect texture or image. This usually occurs when the geometry of an object has changed for some reason, for example, as a result of map clipping, moving the object, or adding or removing nodes. Use the Refresh Texture command on the shortcut menu in the Prism Map window to correct the display.

Modifying a Prism Map

To modify the properties of a Prism Map:

1. Right-click to display the shortcut menu, and then choose Properties.

   The Prism Map Properties dialog box opens.

2. Modify the Background and Light color settings.
3. Select InfoTips and set a scale for the Z direction (vertical) of the map.

   The InfoTip information can come from any column in the table or valid expression. The values will display when you hover the cursor over an object using a command that supports ToolTips.

   A scale for the Z direction is calculated during the initial creation of the Prism Map. If you decide to modify it, keep in mind that the values used for the prism height may greatly exceed the x and y dimensions.

   For example, in a Prism Map of population, values could easily be in the millions. The scale must be small enough so that the objects can be viewed. A scale value >1 will exaggerate the topology in the Z direction; a value <1 will scale down the topological features in the Z direction.

4. Click OK.

The prism properties save and are applied to the map.

Refreshing the Grid Texture of a Prism Map

You can regenerate the image that is used for the texture on the grid. This is useful when the tables change or objects are updated.

To refresh the grid texture of a Prism Map:

1. Make the Prism Map the active window.
2. Right-click on the map and choose Refresh Texture.

The image is regenerated.