The "Map.h" header provides an optional slam map data interface considering most visual SLAM systems are using such structure, where a Map is constructed by MapPoints and MapFrames, relationship between point and frame calls observation, relationship between frames calls connection.

This may not suit every SLAM system but make sense to unify the map access interface.

The interface is consisted with four class APIs:

• MapFrame: A frame is one sensor status captured from any time or any sensors. Every frame has an unique id with timestamp and pose status information.
• MapPoint: A map point is one landmark to describe the world structure, it should be observed by some map frames.
• Connection: It describes the relationship between two map frames, such as pose constrains, keypoint matches.
• Map: It is used to manage the mapframe and mappoints.
• LoopDetector: Used to index mapframes and detect loop candidates.

Since the header only provides interface but no implementation. Users should inherit the class, provides real data and implement the virtual functions.