Abstract: A three-dimensional ultrasonic scanning apparatus produces projection pictures on the surface of an object under inspection or examination and on planes perpendicular thereto. The amplitudes of the echo pulses produced by the ultrasonic scanning appartus, which uses an angle probe, are stored in a memory having at least one storage position relating to each projection of a reflecting point within the examined area. Only the highest echo amplitude originating from all the reflecting points lying on a projection line at right angles to the projection plane in question is recorded--not the highest amplitude from each reflecting point on the projection line. Thus, only those echo pulse amplitudes necessary to produce a projection picture of the object are stored in the memory thereby substantially reducing the required memory capacity.