A shared-housing ultrasound transducer and machine-vision camera system is disclosed for registering the transducer's x, y, z position in space and pitch, yaw, and roll orientation with respect to an object, such as a patient's body. The position and orientation are correlated with transducer scan data, and scans of the same region of the object are compared in order to reduce ultrasound artifacts and speckles. The system can be extended to interoperative gamma probes or other non-contact sensor probes and medical instruments. Methods are disclosed for computer or remote guiding of a sensor probe or instrument with respect to saved positions and orientations of the sensor probe.