Producing data describing target measurements

A method of producing on a vehicle data describing target measurements of one or more target positions using a processor in a system having at least one sensor on-board the vehicle, the method including:

• obtaining first on-board sensor data representative of a target from said on-board sensor;
• obtaining from an off-board sensor of an off-board vehicle co-operator first off-board sensor data representative of said target;
• associating track data obtained by said on-board sensor with corresponding track data from said off-board sensor to create a first on-board/off-board track pair;
• approximating a target alignment error in relative alignment of a frame-of-reference of the on-board sensor and a frame-of-reference of the off-board sensor between said first on-board sensor data representative of said target and said first off-board sensor data representative of said target for said first on-board/off-board track pair;
• subsequently obtaining second on-board sensor data representative of said target from said on-board sensor and obtaining second off-board sensor data representative of said target from said off-board sensor;
• receiving alignment error data derived from said second on-board and off-board sensor data;
• estimating a bias using said received alignment error data and correcting said approximated target alignment error using said bias;
• and
• performing a data fusion process on the obtained first off-board sensor data and the obtained first on-board sensor data using said corrected approximated target alignment error to produce target measurement data of said target.