Since 1995, RC&A has provided helicopter-based aerial photography for photogrammetric purposes. Our services have been contracted by State Departments of Transportation in Virginia, North Carolina, Tennessee, New Jersey, Pennsylvania, Connecticut, Maryland, Delaware, Michigan, Illinois, and Iowa for highway design and related engineering. In addition, these services have been used in other fields where very high accuracy is required and ground surveys are difficult or problematic. The helicopter has also proven useful where congested airways make regular surveys difficult to accomplish with fixed-wing aircraft.
The cornerstone of our system is the Bell Jet Ranger helicopter. The first such system in its class, this helicopter has been modified so that the aerial camera system is totally enclosed within the aircraft cabin. Unlike competing systems in which the camera is mounted externally, this configuration does not limit the aircraft operation and the camera is accessible and precisely controlled by the photographer. Also, temperature extremes, airflow, and other environmental hazards do not affect the camera system.
The Jet Ranger is equipped with a Racal Landstar differential GPS correction system for precise navigation. Scale (altitude) is maintained with the use of a radar altimeter, as regular pressure altimeters do not allow for sufficient accuracy at altitudes less than 500 feet. The aircraft travels at over 100 miles per hour with a three-hour duration between fuel stops. This allows for quick project turn-around times within a large operating area.
Standard camera equipment is a Leica RC-30 with forward motion compensation and a gyrostabilized platform. The reputation of the RC-30 camera is without equal – this system has proven itself through thousands of images all over the Eastern United States.
SEE OUR GIM COVER
This month's cover shows a Bell JetRanger helicopter, owned and operated by Richard Crouse & Associates of Frederick, Maryland.
This ship has been uniquely modified to carry a Leica RC30 camera system and is capable of producing aerial photography at scales as large as 1:400.
This system has been used extensively not only for high accuracy measurement of road and airport runway surfaces, but also in areas where airspace concerns make fixed wing operation difficult.