The problem

Tracking is the processing of measurements or observations obtained from a target in order to maintain an estimate of its current state

The state of a target usually consists of:

• Kinematics - position, velocity, acceleration , turn rate, etc. expressed w.r.t a coordinate frame
• Feature components - target classificiation, spectral characteristics, radar cross-section etc.

Measurements or observations are noise-corrupted quantities which are related to the state of a target, such as

• Direct estimate of position (GPS)
• Range and azimuth(bearing) from the sensor (radar, cameras)
• Range rate (radar)

The observations are not raw data sequences but usually the output of a complex signal processing subsystem.