Georeferencing a mosaic dataset item

You can georeference a mosaic dataset item to either another raster layer or a feature class. When georeferencing, use well-defined objects in your images, such as road intersections or ground features, to serve as reference features. These objects should be on the ground and not elevated features. This way, you can be assured that you are referencing the same location in both the reference raster and the layers to be georeferenced.

When you georeference a mosaic dataset item, the item is updated in the mosaic dataset, but the source data is not updated. To save the georeferencing of your mosaic dataset item to a file, use the Export Mosaic Dataset Items tool.

Note:

Saving the ArcGIS Pro project does not save the current state of a georeferencing session. Export your control points before you close the project.

The three steps needed to georeference your mosaic dataset item are as follows:

• Select the mosaic dataset item.
• Georeference the mosaic dataset item.
• Update the mosaic dataset.

Select the mosaic dataset item

To georeference an item in a mosaic dataset, select the item and add it to the map as a layer using the following steps:

1. In ArcGIS Pro, add the mosaic dataset you want to georeference.

   The mosaic layer you are georeferencing must be in the same coordinate system as the map frame.

2. Add the reference layers; these layers can be a raster, a feature class, or a basemap.
3. In the Contents pane, select the mosaic dataset.
4. Click the mosaic layer's Data tab.
5. In the Selection group, click the Select tool.
6. In the map display, click the mosaic dataset item you want to georeference.

   You may need to select the item from the table if you can't select the exact item from the map.

   The footprint of the mosaic dataset item will be highlighted on the map display and the attribute table.

7. In the Contents pane, right-click the mosaic layer, point to Selection, and click Add to Map.
8. On the Add selected raster to map dialog box, click OK.
9. Expand the new group layer and make it visible.

Georeference the mosaic dataset item

Use the following steps to georeference the item you selected from the mosaic dataset:

1. In the Contents pane, click the raster layer that was isolated in the previous section.
2. Click the Imagery tab and click Georeference to display the Georeference tab.

   The tools on the Georeference tab are grouped to help you use the correct tool in the proper phase of your georeferencing session.

3. In the Prepare group, click Set SRS .

   Since your mosaic dataset already has a spatial reference, it is automatically used as the coordinate system for the map and the georeferencing session.

4. Optionally turn off the visibility of your mosaic dataset before creating control points.
5. Use the Add Control Points tool or the Auto Georeference tool to create control points.
6. When you have enough control points, use the Transforms drop-down menu to choose the transformation you want to use.

   Zero-order polynomial	Minimum of one control point required
   First-order polynomial	Minimum of three control points required
   Adjust	Minimum of three control points required
   Projective transformation	Minimum of four control points required
   Second-order polynomial	Minimum of six control points required
   Third-order polynomial	Minimum of ten control points required
   Spline transformation	Minimum of ten control points required

7. In the Review group, click the Control Point Table button to evaluate the residual error for each control point.

   Press the L key to switch the transparency of your source raster on and off.

8. Delete any unwanted control points using the Control Point table. Alternatively, edit the inaccurate points by selecting them and moving the vertices.
9. When you're satisfied with the current alignment, stop entering control points.
10. In the Save group, click Save .
11. Click Close Georeferencing .

Update the mosaic dataset

You have georeferenced your mosaic dataset item for your current mosaic dataset, but you must update the footprints to see the updated result using the following steps:

1. Turn off the visibility of the selection group, and turn on the visibility for the mosaic dataset.
2. Click the Analysis tab.
3. Click the Tools button .
4. In the Geoprocessing search window, type Build Footprints.
5. Click the Build Footprints result, which should be the top result.
6. Use the Mosaic Dataset drop-down arrow to choose the name of your mosaic dataset in the current map.
7. Click Run to execute the tool.

   Your mosaic dataset is now updated.

Export the mosaic dataset item to a file

Optionally, you can save the mosaic dataset item to a raster file format in case you want to update your source data or use the updated raster in another mosaic dataset. Keep in mind that the source raster was not updated in any of the steps above. To export your mosaic dataset to a file, complete the following steps:

1. Open the Export Mosaic Dataset Items tool.
2. Use the Mosaic Dataset drop-down list to choose the mosaic dataset that you just updated.
3. Use the Select tool to choose the mosaic dataset item.
4. Choose the Output Folder and Output Base Name parameters.
5. Click Run.
Your mosaic dataset item is exported and can be used in other mosaic datasets. You can also use it to update the base data.