Orthorectification is the process of stretching an image to match the spatial accuracy of a map by considering location, elevation, and sensor information. To orthocorrect a raster dataset, the raster must have rational polynomial coefficients (RPCs) associated with it. For a more accurate result, use the digital elevation model (DEM) as well. Rasters can be orthorectified by modifying the raster layer properties in ArcMap or by using the Image Analysis window. Rasters can also be permanently orthorectified with the Create Ortho Corrected Raster Dataset tool.
The instructions provided describe how to find out if a raster has RPCs, which are required for orthorectification.
There are a couple of ways to determine if a raster has associated RPCs.
- Navigate to the location where the raster is stored in Windows Explorer. In most cases, if the raster has RPCs, there will be an extra file in this location that stores the RPC information. RPC files are stored as one of the two following file type formats:
- Check the Display properties of the raster dataset:
1. Add the raster to ArcMap.
2. Right-click the raster dataset in the Table of Contents.
3. Select Properties > Display.
If the raster dataset has RPCs, the 'Orthorectification using elevation' option is active.
If there are no associated RPCs, this option is grayed out.