Abstract: Systems and methods for ranking geographic features in a geographic information system are provided. In particular, geographic features can be assigned ranking scores based on characteristics of viewsheds associated with the geographic features. In particular, characteristics of a viewshed associated with a geographic feature can be analyzed to assess the visibility of the geographic feature. A ranking score can be assigned to the geographic feature based on the characteristics of the viewshed. The ranking score can be used prioritize information in a geographic information system.

Abstract: Systems and methods for removing hidden faces in a 3D model, such as a building model are provided. A method for removing hidden faces in a 3D building model may include identifying a 3D building model having hidden surfaces inside the building model. The method may further include adding closing surfaces to the hidden surfaces to form closed hidden surfaces. The method may further include combining the closed hidden surfaces into a single polygon. The method may then include removing the closed hidden surfaces. A system for removing hidden faces in a 3D building model may include a surface identifier, a surface adder, a surface combiner and a surface remover. The removal of unnecessary internal surfaces and artifacts may increase the efficiency of the 3D building model.

Abstract: A steering and stabilization system for an aircraft or other vehicle including a device, for the determination of attitude of the vehicle, in which three, or alternatively, two magnetometers are mounted in the vehicle with respect to the direction of its fore-and-aft axis to determine each co-ordinate of a set of three orthogonal co-ordinates of attitude of the vehicle and in which the orthogonal co-ordinates determined by the magnetometers are transformed into respective geodetic co-ordinates.