Abstract: The invention concerns a device for displaying computer-assisted realistic virtual three-dimensional images, and pictured by computerisation into a real environment, characterised in that it comprises in combination: means for detecting and monitoring in real time the user's position in the geographical site for implanting the virtual objects, relative to an arbitrary reference point; means for detecting and monitoring in real time the position of the users' field of vision (top, bottom, right, left) relative to a reference point located with respect to the user, video means for capturing and monitoring in real time the images perceived by the user, means for computing virtual images in real time taking into account the user's position and the field of vision previously detected; means for mixing the resulting computed virtual video image previously captured, such that the virtual image is pictured on the video image realistically and non-transparently.