1. A system for generating an image comprising information of an interior and an exterior of a patient, the system comprising: an X ray device for providing an X ray image of a patient's interior, a camera responsive to a wavelength for providing a camera image of a patient's exterior, the camera being supported by the X ray device for establishing a determined spatial relationship between the camera and the X ray device, a spatial reference for spatially correlating the X ray image and the camera image, the spatial reference being detectable in the X ray image and in the camera image, and a data processor for rendering the camera image and the X ray image into a composite image on the basis of the spatial reference, wherein the spatial reference includes a movable marker for increasing an accuracy of the spatially correlating, the movable marker being installed on the patient's exterior near a surgical field that corresponds to a location at which a medical intervention is to be carried out, wherein the movable marker comprises at least three mutually remotely located marker points, wherein the three mutually remotely located marker points are detectable and displayed in both the X ray image and in the camera image, further wherein the spatially correlating is enabled through connecting the three mutually remotely located marker points in the X ray image with corresponding marker points in the camera image, further wherein the movable marker allows for removal from the surgical field after establishing a spatial correlation.