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.
Landmark matching. The red point is the turn landmark, and the green points are the door landmarks. The yellow points are the PDR position when a turn is detected. The blue points are the PDR position when opening a door is detected. The dashed red line indicates the nearest landmark points.
