The present disclosure relates to a method and apparatus for localizing an object in space, such as a gallstone in a human, using stereo imaging and ultrasound imaging. The localization system is described in connection with a dry table shock wave lithotripter, and uses a conventional ultrasound imaging system but wherein the ultrasound transducer has been modified to enable its location in space to be readily determined automatically. This is accomplished by providing a hood fixed to this transducer, the hood having a plurality of reference points which may be in the form of light sources such as LEDs. This hood is imaged by head and foot video cameras. By calibrating the cameras with respect to a reference point, calibrating the focal point of the shock wave system with respect to the reference point, and knowing the relationship of the hood to the ultrasound transducer, the position of the stone with respect to the reference point can be determined by ultrasound imaging of the stone, along with suitable storage of the ultrasound and camera images, digitizing and processing of these images. Given this information, the patient with the stone can be suitably moved so as to position the stone at the focal point of the shock wave generating system.