1. A device for representing augmented-reality information for a user, comprising: a spatial detection unit having a spatial detection device for positioning on the head of a user to be stationary relative to an eye of the user that moves relative to movement of the head of the user, wherein the spatial detection unit continuously (a) detects surface distance points for only a viewable surface of an actual reality which represents only a part of the actual reality that is in a field of view of the user and not obstructed by surfaces in front of it rather than an entire actual reality in three-dimensions, and (b) dynamically generates from the surface distance points detected corresponding spatial information comprising a partial surface model of only the viewable surface rather than the entire actual reality in three-dimensions, wherein the spatial information comprises limited information used for calculating partial masking surfaces for only the viewable surface rather than a complete 3D surface model of the entire actual reality, thereby reducing cost calculations by using the partial masking surfaces rather than the complete 3D surface model of the entire actual reality; an ambient detection unit for positioning on the head the user to be stationary relative to the spatial detection device and the eye of the user that moves relative to movement of the head of the user, wherein the ambient detection unit continuously detects ambient information representing a position and an angular field of the user with respect to the actual reality; a storage unit comprising three-dimensional (3D) object data describing a virtual object; a processing unit that receives the continuously dynamically generated partial surface model for only the viewable surface of the actual reality in the field of view of the user, the ambient information representing position and angular field of the user with respect to the actual reality, and the 3D object data describing the virtual object; continuously constructs a 3D surface model of the actual reality that comprises only content of the actual reality required for calculating masking surfaces based on the partial surface model detected and the ambient information representing relative movement of the head of the user changing the field of view of the user, rather than a complete 3D model of the actual reality; calculates which surfaces of the virtual object are to be masked by the viewable surface of the actual reality based on the continuously dynamically generated spatial information without using the complete 3D surface model of the entire actual reality; generates a new data set for display to the user as an augmented-reality comprising a virtual model that describes the virtual object with the surfaces of the virtual object masked by the viewable surface of the actual reality blanked out; and displays to the user via a reproducing unit the augmented-reality inserted into the field of view of the user while the user directly observes the actual reality or indirectly observes a separately captured viewable image of the actual reality.