Bulletin Géodésique (1946-1975)

, Volume 114, Issue 1, pp 335–347 | Cite as

An evaluation of horizontal control networks in Canada

  • C. David McLellan


Current coordinate values are based on the 1927 North American Datum. At the time of re-adjustment based on this datum Canadian triangulation consisted of limited networks along and close to the U.S. boundary. Since then, loops of triangulation have been built up and adjusted one by one as completed. Distortions resulting from this process have become evident with the introduction of electronic distance measuring equipment.

In March 1972 a program was initiated to assess the existing horizontal control framework in Canada to determine how it should be strengthened and extended to form a reasonably uniform control grid and to meet long range needs. Results indicate where there are weaknesses and distortions in the existing networks. Using adjustment program GALS the network was processed and evaluated in sections. The evaluation and classification is based on confidence region.

A complete re-adjustment of the framework is planned. A redefinition of datum based on satellite observations will likely be one step. Strengthening and completion of the framework is essential. The assessment project aids in identifying weak areas and prepares all data in computer compatible form for the first time. The data eventually will be entered on an automated file from which information can be drawn for further adjustments and analysis.

A method of adjustment by sections is being investigated as a possible way of re-adjusting the framework. How satellite observations will be used is not yet determined.


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Copyright information

© Bureau Central de L’Association Internationale de Géodésie 1974

Authors and Affiliations

  • C. David McLellan
    • 1
  1. 1.Geodetic Survey of Canada(Canada)

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