An image correspondence feature contains the position of one same feature across a set of views. The views are images of a dataset. The feature is one common object point, seen images captured from different positions. Optionally, it can also store a depth, and a weight for the feature point on each view.
Image correspondences are a set of image correspondence features. The features may cover different subsets of views, and may have different reference views.
The image correspondence feature can optionally have one reference view. It means that for the reference view, the feature position was freely chosen, whereas for the other views, it was chosen so as to correspond to the same object position. The Image correspondences can contain features with different reference views.
A feature points file stores the set of feature points (position, depth, weight), for only one view.
The tool calibration/cors_info displays information about an image correspondences file.
To merge multiple image correspondences files together into one, use calibration/merge_cors. This does not lose any information.
The tool calibration/cg_optical_flow_cors generates image correspondences by tracking the optical flow of features on all images of a dataset. The features to track on the reference view are chosen using the tool calibration/cg_optical_flow_features.
The tools calibration/cg_cors_viewer_f and calibration/cg_cors_viewer_v are used to visualize image correspondences in a GUI.
calibration/cg_cors_viewer_f shows the position of a given feature on the different views.
calibration/cg_cors_viewer_v shows the positions of the features on a given view.
Image correspondences can be stored either in a JSON format, or in a binary format. For large number of image correspondences (such as optical flow on a dense dataset), the binary format takes up much less space, and loads faster.
On every tool that takes a .json argument for a image correspondences file (input or output), giving a .bin filename instead uses the binary format.
The tool calibration/copy_cors copies image correspondences from one file to another, enabling conversion from/bin binary.