Georeferencing a raster to a vector

When georeferencing, you should look for well-defined objects within your images, such as road intersections or land features. This way you can be certain that you are referencing the same location in both the raster and aligned layers. You can georeference a raster dataset, a raster layer that contains raster functions, an image service, or a mosaic layer. Some of the Georeferencing options may be helpful to make your georeferencing task easier.

Note:

The Georeferencing toolbar layer list will display raster layers and CAD layers as valid data types. The layers must either be in the same coordinate system as the data frame or have no spatial reference defined.

1. In ArcMap, add the layers residing in map coordinates and add the raster dataset you want to georeference.

   Adding the data with the map coordinate system first is a good practice so you do not need to set the data frame coordinate system.

2. To display the Georeferencing toolbar, click the Customize menu and click Toolbars > Georeferencing.
3. 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 Extent Used By Full Extent Command, within the Data Frame Properties, to your study area so the Zoom to Full Extent tool will automatically zoom to the full extent of your study area.

4. From the Georeferencing toolbar, click the Layer drop-down arrow and choose the raster layer you want to georeference.
5. Click the Georeferencing drop-down menu and click Fit To Display.

   This displays the raster dataset in the same area as the target layers. You can also use the Shift and Rotate tools to move the raster dataset as needed. To see all the datasets, adjust their order in the table of contents.

6. Click the Add Control Points tool to add control points.
7. To add a link, click a known location on the raster dataset, and click a known location on the vector layers in map (the reference data).

   You can also add your links in the Magnification window or the Viewer window. If you are using polygons as your referenced layer, you can open the Effects toolbar to adjust the transparency as you add your links.

   Tip:

   Press Esc to remove a link while you're in the middle of creating it.

   Note:

   The Rotate and Shift tools are not available after you place the first link.

8. Add enough links for the type of transformation you will apply.

   You need a minimum of 1 link for zero-order polynomial, 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.

9. Click the View Link Table button to evaluate the transformation.

   You can examine the residual error for each link and the root mean square (RMS) error. If you're satisfied with the registration, you can stop entering links.

10. Delete any unwanted links from the Link table.
11. 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.

Note:

You can permanently transform your raster dataset after georeferencing by using the Rectify command (click the Georeferencing drop-down menu and click Rectify), the Warp tool, or the Warp From File tool.

Note:

Updating a raster layer, an image service, or a mosaic layer only updates the layer within your map document; it does not save the georeferencing information back to the source.