Automatic ground control point (GCP) collection techniques use image correlation to identify the pixel and line locations in the raw image that correspond to features in a georeferenced image or to georeferenced positions on chips. This can be useful for repeat mapping, such as resource or municipal mapping, or creating continuous composites.
For projects using the Satellite Orbital math model or the Rational Functions math model with RPC provided, you can match points based on an approximate image model derived from the orbit information. For projects that use other math models, the matching process can be accomplished if your project meets one or more of the following criteria:
- The exterior orientation of each image was computed based on ground control points (GCPs) and tie points.
- You have three tie points between every pair of overlapping images.
- A Global Positioning System (GPS) was used to obtain the x, y, and z coordinates for each image center, and you estimated the omega, phi, and kappa rotations, or they were supplied by an Inertial Navigation System (INS).