Method for determining a spatial correction of a primary ultrasonic emitter by evaluating the ultrasonic signal emitted by the primary ultrasonic emitter and received by at least three ultrasonic receivers (8, 9, 10) calibrated in space, wherein the primary ultrasonic emitter is arranged in a coplanar emitter array with at least two secondary ultrasonic emitters (3, 4) and the nominal emission direction of the primary ultrasonic emitter is known relative to the coplanar emitter array, and wherein the ultrasonic receivers (8, 9, 10) are positioned to receive ultrasonic signals from the primary ultrasonic emitter and the at least two secondary ultrasonic emitters (3, 4) of the emitter array, said method comprising the following steps: - emitting consecutively ultrasonic signals from the primary ultrasonic emitter and the secondary ultrasonic emitters (3, 4); - measuring the runtime of the ultrasonic signal to the ultrasonic receivers (8, 9, 10) and determining an uncorrected position of the ultrasonic emitter for each of the primary ultrasonic emitter and the secondary ultrasonic emitters (3, 4) on basis of the runtime of the ultrasonic signal; - determining the normal ( n) of the plane of the emitter array wherein the plane is defined by the uncorrected positions of the primary ultrasonic emitter and the coplanar secondary ultrasonic emitters (3, 4); - determining the emission angle ( β, φ) between the nominal emission direction of the primary ultrasonic emitter and the direction of a straight line between the primary ultrasonic emitter and one of the ultrasonic receivers for each of the ultrasonic receivers (8, 9, 10); - determining the uncorrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10); - determining a distance correction value ( δR) for the distance between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10) depending on the respective emission angle ( β, φ); - applying the respective distance correction values ( δR) to the uncorrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (3, 4) to receive corrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10); - determining a corrected position of the primary ultrasonic emitter on basis of the corrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10). - emitting consecutively ultrasonic signals from the primary ultrasonic emitter and the secondary ultrasonic emitters (3, 4); - measuring the runtime of the ultrasonic signal to the ultrasonic receivers (8, 9, 10) and determining an uncorrected position of the ultrasonic emitter for each of the primary ultrasonic emitter and the secondary ultrasonic emitters (3, 4) on basis of the runtime of the ultrasonic signal; - determining the normal ( n) of the plane of the emitter array wherein the plane is defined by the uncorrected positions of the primary ultrasonic emitter and the coplanar secondary ultrasonic emitters (3, 4); - determining the emission angle ( β, φ) between the nominal emission direction of the primary ultrasonic emitter and the direction of a straight line between the primary ultrasonic emitter and one of the ultrasonic receivers for each of the ultrasonic receivers (8, 9, 10); - determining the uncorrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10); - determining a distance correction value ( δR) for the distance between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10) depending on the respective emission angle ( β, φ); - applying the respective distance correction values ( δR) to the uncorrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (3, 4) to receive corrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10); - determining a corrected position of the primary ultrasonic emitter on basis of the corrected distances between the primary ultrasonic emitter and each of the ultrasonic receivers (8, 9, 10).