Abstract: A measurement system has a measurement scale pattern (10) and sensor (12) moveable relative to one another. The measurement scale pattern has a pattern of features (14) arranged into groups, each group having a known absolute position. The sensor (12) has a field of view sufficient to detect one or more features simultaneously. Relative movement between the sensor (12) and measurement scale pattern (10) is constrained in two or more degrees of freedom. A processor determines the position of the sensor or an object connected to the sensor relative to the measurement scale pattern in at least one linear and one rotational degree of freedom.