A software system processes navigational and sensory information in real time to generate a three- dimensional- appearing image of the external environment for viewing by crewmembers of a windowless aerospacecraft. The design of the particular aerospacecraft (the X-38) is such that the addition of a real transparent cockpit window to the airframe would have resulted in unacceptably large increases in weight and cost.

When exerting manual control, an aircrew needs to see terrain, obstructions, and other features around the aircraft in order to land safely. The X-38 is capable of automated landing, but even when this capability is utilized, the crew still needs to view the external environment: From the very beginning of the United States space program, crews have expressed profound dislike for windowless vehicles. The well-being of an aircrew is considerably promoted by a three-dimensional view of terrain and obstructions. The present software system was developed to satisfy the need for such a view. In conjunction with a computer and display equipment that weigh less than would a real transparent window, this software system thus provides a "virtual cockpit window."

The key problem in the development of this software system was to create a realistic three-dimensional perspective view that is updated in real time. The problem was solved by building upon a pre-existing commercial program — LandForm C3 — that combines the speed of flight-simulator software with the power of geographic-information-system software to generate real-time, three-dimensional-appearing displays of terrain and other features of flight environments. In the development of the present software, the pre-existing program was modified to enable it to utilize real-time information on the position and attitude of the aerospacecraft to generate a view of the external world as it would appear to a person looking out through a window in the aerospacecraft. The development included innovations in realistic horizon-limit modeling, three-dimensional stereographic display, and interfaces for utilization of data from inertial-navigation devices, Global Positioning System receivers, and laser rangefinders. Map and satellite imagery from the National Imagery and Mapping Agency can also be incorporated into displays.

After further development, the present software system and the associated display equipment would be capable of providing a data-enriched view: In addition to terrain and obstacles as they would be seen through a cockpit window, the view could include flight paths, landing zones, aircraft in the vicinity, and unobstructed views of portions of the terrain that might otherwise be hidden from view. Hence, the system could also contribute to safety of flight and landing at night or under conditions of poor visibility.

In recent tests, so precise was the software modeling that during the initial phases of the flight the software running on a monitor beside the video camera produced nearly identical views.

This work was done by Michael F. Abernathy of Rapid Imaging Software, Inc., for Johnson Space Center. For further information, please contact Michael F. Abernathy, Rapid Imaging Software, Inc., 1318 Ridgecrest Place S.E., Albuquerque, NM 87108. MSC-23096.