Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Semantic landmark and adjacent segments. An adjacent segment consists of four parts: Id, distance, direction and semantic description. Id is the identifier of a segment. Distance represents the distance between the two landmarks that make up the segment. Direction represents the direction of the segment. Semantics indicates the semantic information that can be obtained.
