Do you often have to georeference raster datasets? Do you find a lot of time is consumed with setting up control points?
Georeferencing was introduced with ArcGIS Pro 1.4 and has the capability to speed up your georeferencing workflows. Auto georeference allows you to automatically georeference your raster dataset to a referenced raster dataset (this can even be a basemap from your Portal or ArcGIS Online). The automated control points are based on the spectral signatures of different locations across the images, so this method is best suited for aerial and satellite imagery which are similar in nature.
Here is an overview of the steps involved:
- Add a referenced raster to your map. This will be your control raster. In my example, I am just using the imagery basemap from ArcGIS Online.
- Add the raster dataset you want to georeference
- Now you will want to activate the Georeference tab, to do this click Imagery and then Georeference
- In the Prepare group, click Set SRS. If you dataset already has a spatial reference, it will be automatically used as the coordinate system. If your raster does not have a spatial reference, the Map Properties dialog box will appear and you can choose the coordinate system.
- With the help of the Locate, zoom to a location where your source raster is located. Now click Fit to Display, to roughly draw your raster over the current location on the map.
- Use the remaining tools under the Prepare group, such as Move, Scale and Rotate to adjust the raster as needed. To achieve a good success rate in auto georeferencing, the two images should be a similar as possible, geographic location, time, season, image orientation, scale and band combination.
- Whilst roughly aligning the raster, you may also like to change the cursor to swipe and adjust the transparency of the raster. This can be done by clicking the Appearance tab.
- Now you should be all set to watch the magic. In the Adjust group, click Auto Georeference button. The system will attempt to match your raster to the reference layer.
- In the Review group, click the Control Point Table button to evaluate the residual error for each control point and delete any unwanted control points.
- In you are satisfied with the current alignment, in the Save group, choose how you want to save your georeference information.
Auto georeferencing does speed up your georeferencing workflows, however why not go one step further and incorporate the steps as a Task? Once the task has been created it then could be shared among fellow colleagues and could even further automate the entire process. Here is a short demonstration where I use a task to georeference a raster in less than a minute.