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The Add Control Points tool is the tool that allows you to georeference the image. This is the process of matching points on the image layer to corresponding points on the shape layers.

Add Control Points Using Latitude and Longitude

You can enter x (longitude) and y (latitude) coordinates as Control Points rather than use the method mentioned above. To do this,

1. Left click on a known point on the image. This will place a cross mark on that location.
2. Right click on the point you just created. A menu will appear.
3. Choose Input X and Y. The Enter Coordinates dialog box will appear.
4. Enter the coordinates in the appropriate boxes.

Add Control Points Using Visual Cues

Control points can be added using visual cues. These usually take the form of visible landmarks, like the corner of a sharply defined agricultural plot of land, or the bend of a river.

Note: it is a good idea to zoom in on your image when adding control points for better accuracy.*

1. In the Georeferencing pull down menu, make sure that Auto Adjust is turned off (no check mark).
2. Add a Georeferenced Basemap to your new Map Project.  We recommend adding the ESRI Imagery World 2D Map or ESRI Street Map World 2D from the ESRI servers.
3. In the Table of Contents, drag the Basemap below the image you are georeferencing. That will allow you to see the image superimposed on the Basemap.
4. Select the  Add Control Points button
   Add Control Points Button
   
   
   
5. Left click on a known point on the image. This will place a cross mark on that location.
6. Left click on the matching control point in your Basemap. This will 'move' the image and better align the control points.
7. Repeat this step with each control point.

Add Control Points Using Latitude and Longitude

You can enter x (longitude) and y (latitude) coordinates as Control Points rather than use the method mentioned above. To do this,

1. Left click on a known point on the image. This will place a cross mark on that location.
2. Right click on the point you just created. A menu will appear.
3. Choose Input X and Y. The Enter Coordinates dialog box will appear.
4. Enter the coordinates in the appropriate boxes.

For every set of control points you create, an entry is created in a table that records the original coordinates, the control point coordinates, and the residual error. Access the table by choosing the View Link Table icon from the Georeferencing toolbar

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