Method of determining a position and/or orientation of a hand-held device with respect to a subject, a corresponding apparatus and a computer program product

Abstract

According to an aspect, there is provided a method of determining a position and/or orientation of a hand-held device with respect to a subject. The hand-held device is for use on a body of the subject. The method comprises receiving () images from an imaging unit arranged in or on the hand-held device; receiving () a displacement signal from a displacement sensor that is arranged in or on the hand-held device to measure displacement of the hand-held device along the body when the hand-held device is in contact with the body; processing () the received images to determine whether a body part of the subject can be identified in the received images; determining () whether the hand-held device is in contact with the body; determining () a mode of operation to use to determine a position and/or orientation of the hand-held device based on whether a body part can be identified and whether the hand-held device is in contact with the body; wherein the mode of operation to use is determined as (i) a first mode when a body part can be identified, (ii) a second mode when a body part cannot be identified and the hand-held device is not in contact with the body, and (iii) a third mode when the hand-held device is in contact with the body; and determining () the position and/or orientation of the hand-held device with respect to the body of the subject using the received images and/or received displacement signal according to the determined mode of operation.