Summary
The process for georeferencing raster data to a reference layer is documented in the book 'Using ArcMap'. However, it is also possible to georeference raster data to known points without a reference layer.
Procedure
The coordinates to which the raster image will be georeferenced and the coordinate system (projection) of those coordinates must be known before beginning this process.
- Open ArcMap with a new, empty map, and add the raster data to be georeferenced to the ArcMap session.
- Open View > Data Frame Properties > Coordinate System tab > Predefined, and browse to the Coordinate System of the output coordinates you will use in this process.
Note:
For example, if the output coordinates are in NAD 1983 UTM Zone 15N, you will set the projection of the Data Frame to that coordinate system.
- Add the Georeferencing toolbar to ArcMap.
- Zoom in to the first point on the raster image that will be used as a control point, then click the Add Control Points tool.
- Place the cursor over the first control point in the raster and right-click.
- Move the curser slightly and right-click.
- Select Input X and Y.
- Enter the known output coordinates for this control point and click OK.
- Enter enough points for the desired transformation order.
Note:
For further information on the number of control points needed, refer to ArcGIS Desktop Help: About georeferencing > Transforming the raster.
- Click View Link Table to evaluate the transformation.
- Click the Georeferencing menu and select the Update Georeferencing option to save the transformation information with the raster.