Aerodist in Geodetic Surveying in Canada

Abstract

In 1962, the Topographical Survey Division of the Surveys and Mapping Branch, Department of Energy, Mines and Resources, acquired an aerodist survey system for use in the rapid extension of horizontal control for mapping in Canada. The following year, with the cooperation of the Geodetic Survey Division, the system was tested on a geodetic net in the Ottawa area for possible application in extending first-order horizontal control. Aerodist length measurements were made using the line-crossing technique. The results were most encouraging and in 1965, federal topographers and geodesists used aerodist trilateration to span Hudson Strait and northern Hudson Bay. In 1966, they established an extensive aerodist network in western Canada, connecting two previously established geodetic nets and observed test data on the continuous trilateration method for future analysis. The paper describes the aerodist measurement procedure and the reduction of observed data, and discusses sources of error and the accuracy of aerodist measurements, based on analysis of work completed to date. The paper also outlines future developments, including incorporation of a small electronic computer as part of the aerodist airborne unit, employment of electronic circuitry for obtaining meteorological data in the aircraft and a computer program to adjust continuous trilateration data. General factors affecting future applications and proposed future work are also included.