The present invention relates the device and the method for providing a guidance signal. The device preferably relates to a mobile device, such as a mobile tablet computer. The device comprises an input unit, a display and a processing unit. Via the input unit, a three-dimensional outline image of a surface of a human subject is provided, e.g. acquired by a camera. The device further comprises a memory. The memory stores a human reference model, which statistically represents a virtual human subject. In practice it is often the case that the surface outline represented by the human reference model would not instantly fit to the surface outline of the human subject. Therefore, the processing unit is configured to adapt the human reference model resulting in an adapted model, such that the surface outline represented by the adapted model fits to the surface outline of the (real) human subject. Furthermore, the image is acquired as a so-called track-image of an ultrasonic handheld transducer in front of the human subject. The processing unit is configured to recognize the ultrasonic handheld transducer in the track-image and to determine the transducer pose based thereon. In practice, the ultrasonic handheld transducer is to be arranged on the surface of the human subject at a target pose in order to scan a desired scan region of the human subject. The scan region may relate to an inner organ of the human subject. Based on the actual transducer pose and the desired target pose, the processing unit is configured to determine a guidance signal, which indicates how to move and/or rotate the ultrasonic handheld transducer to reach the desired target pose.
