Problem: Why does the spatial reference change when exporting Data Driven Pages?
Data Driven Pages exported from ArcMap are in a different spatial reference (coordinate system) than the map document.
The spatial reference in the Set Up Data Driven Pages dialog box is set to a different Well-Known ID (WKID) than the projection of the ArcMap data frame.
By default, Data Driven Pages are exported to the spatial reference of the ArcMap data frame. However, Data Driven Pages can also be exported to a different spatial reference; for example, if a field exists in the Index Layer that contains the Well-Known ID (WKID) for a different coordinate system and that field is selected as the spatial reference.
Note: The Spatial Reference field can contain the name of the projection definition or the entire Projection Engine (PE) string. However, using the WKID as the identifier is recommended as these names or entire strings can be extremely long.
Solution or Workaround
Instructions provided describe how to export Data Driven Pages to both the default spatial reference and an optional spatial reference.
Default Spatial Reference To export Data Driven Pages to the spatial reference of the ArcMap data frame:
1. Open the Data Driven Page Setup from the Data Driven Pages toolbar.
2. On the Definition tab under Optional Fields, verify that the Spatial Reference is set to 'none'. 3. Click OK to close the Data Driven Page Setup.
Optional Spatial Reference To specify a different spatial reference for the exported Data Driven Pages:
1. Add a field for the spatial reference in the index layer's attribute table.
A. Right-click on the index layer and select Open Attribute Table. B. In the attribute table, click the Table Options button to open the drop-down context menu and select Add Field. C. In the Add Field window, provide a name for the field -- for example, 'TheWKID' -- and select Short Integer for the type. D. Click OK.
2. Start an edit session and add the WKID to the new field.
Find the WKID value in ArcMap 10.1 by doing the following: A. Go to View > Data Frame Properties > Coordinate System tab. B. Open the folder Geographic Coordinate Systems or Projected Coordinate Systems and browse to the directory that contains the projection definition needed for the output. C. Click the projection definition. The WKID number for that projection is displayed in the Current coordinate system window below.
3. Open the Data Driven Page Setup from the Data Driven Pages toolbar. 4. On the Definition tab under Optional Fields, select the new field that contains the WKID from the Spatial References drop-down menu.
The exported Data Driven Pages are created in the specified spatial reference.