Control point files are text files that contain destination coordinates that define part of an adjustment. Spatial adjustment supports tab-delimited control point files that contain either two or three columns. A two-column control point file consists of a pair of destination coordinate values. A three-column control point file consists of an ID column (string or numeric) that precedes a pair of destination coordinate values. Control points may represent known locations of features from GPS or ground survey and are displayed in the Control Points window. You can create a control point file in ArcMap or in any ASCII text editor, such as Microsoft Notepad.
Unlike link files, opening a control point file does not automatically create displacement links. You must manually create the links from the control points. This requires that you open the Control Points window with the View Control Points command and double-click each row to create a destination link in the map. Once the link is created at the destination location, you must finish adding the link to the source location. This connects the source feature to the target feature. Repeat this process until all the control point rows are removed from the Control Points window.
- Click the Spatial Adjustment menu, point to Links, then click Open Control Points File.
- In the Open dialog box, click the Look in drop-down arrow and navigate to the folder in which the control point file resides.
- Double-click the control point file to load it.
The Control Points window appears.
- Double-click a row in the Control Points window. This creates a link at the destination location.
- Drag the endpoint of the link to the source location and click once to finish adding it.
The row is now removed from the Control Points window.
- Repeat the process until all the rows in the Control Points window are removed and converted to displacement links.