Hybrid orientation system

A system comprising:

• a camera adapted to capture frames and to provide image data of each captured frame;
• an orientation detector comprising at least one sensor, wherein said at least one sensor outputs orientation data indicative of an orientation of the camera relative to an inertial frame of reference, said at least one sensor comprising one of a magnetometer, an accelerometer and a gyroscope;
• a GPS receiver adapted to generate location data indicative of a location of the system;
• and
• a processor adapted to:
• upon receiving, from said camera, respective image data of a captured frame, identify reference objects in the respective image data;
• calculate a velocity vector of the system using the location data;
• calculate a first orientation of the camera relative to the velocity vector based on a displacement of at least one of the identified reference objects between at least two of the captured frames;
• calculate a second orientation of the camera relative to the velocity vector based on first orientation data output by said at least one sensor;
• calculate a correction for the orientation data based on an angular difference between the first orientation and the second orientation;
• and
• upon receiving second orientation data output by said at least one sensor, correct the second orientation data using the calculated correction, so as to compensate for a bias in the orientation data.