When georeferencing, you should look for well-defined objects within your images, such as land features. This way you can be certain that you are referencing the same location in the raster. You can georeference a raster dataset, a raster layer that contains raster functions, an image service, or a mosaic layer.
- In ArcMap, add the raster layer(s) residing in map coordinates, then add the raster dataset you want to georeference.
Adding the data with the map coordinate system first is a good workflow, so that you do not need to set the data frame coordinate system.
- To display the Georeferencing toolbar, click the Customize menu, and click Toolbars > Georeferencing.
- In the table of contents, right-click a target layer (the referenced dataset) and click Zoom to Layer.
It may be helpful to set your Data Frame Properties Extent used by full extent command to your study area, so that the Zoom to Full Extent tool will automatically zoom to the full extent of your study area.
- From the Georeferencing toolbar, click the Layer drop-down arrow and click the raster layer you want to georeference.
- Click the Viewer button on the Georeferencing toolbar.
This will open up a new Viewer window that displays the raster that you are trying to georeference.
- In the Viewer window, click the Reposition button to automatically make the two windows the same size. Or optionally, you can manually resize the windows.
- From the Georeferencing toolbar, click the Add Control Points button to add control points.
- To add a link, click a known location in the Viewer window, then click a known location on the reference rasters in map coordinates (the referenced data).
You can also add your links in the Magnification window.
- Add enough links for the type of transformation you will apply.
You need a minimum of 1 link for a zero-order shift, 3 links for a first-order polynomial or adjust transformation, 4 links for a projective transformation, 6 links for a second-order polynomial, and 10 links for a third-order polynomial or spline transformation.
- Click the View Link Table button to evaluate the transformation.
You can examine the residual error for each link and the RMS error. If you're satisfied with the registration, you can stop entering links.
- You can delete an unwanted link from the Link Table dialog box.
- Click the Georeferencing drop-down menu and click either Update Georeferencing or Rectify.
Updating the georeferencing will save the transformation information with the raster and its auxiliary files. Rectifying will create a new file with the georeferencing information.