The issue of radar visibility reducing of objects is currently very topical. Interest in this subject is due to the variety of different radars, reconnaissance drones and homing rockets and other high-precision weapons. The most popular way of radar visibility reducing of complex shape target is applying of radio absorbing cloak and optimization of the object design. However, both methods have their own drawbacks, one of which is the high cost of radio absorbing materials and difficulty in changes in design of finished object. Thus it is apparent, that one needs for some kind of method, which would allow assessing the contribution of each radar visibility reducing method. In this paper the angular dependence of the radar cross section data for the two on-ground facilities are compared. Radar data processing method with new introducing quantities is proposed. This method allows getting quickly and accurately assessing to the data about visibility of the facility, located on any of the underlying surfaces, as well as evaluating the effectiveness of visibility reducing events.