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HISTORY OF GEODETIC DATUM

Elevations (benchmarks) have been established throughout Canada based on conventional levelling whose observations date back to 1904. There are approximately 80,000 benchmarks over 120,000 kilometres of levelling lines. The values were revised in: 1931; 1963; 1965; 1971; 1978 and 1980. In 1988 unexplained discrepancies of the order of 1.5 metres hindered an adjustment being implemented. The geodetic datum in place does not represent today's required accuracy and the responsible Federal Agency acknowledges that there are distortions of up to one metre.

INTERNATIONAL GREAT LAKES DATUM

Is based on Geodetic Datum AND the Elevations (benchmarks) location. The location of the Benchmark plays a pivotal role in the adjustment factor applied to the Geodetic.We have found as much as 2 Kilometres between the published value and the actual location of a monument.

CANADIAN SPATIAL REFERENCE SYSTEM

With the cutbacks in government funding, minimal vertical leveling validation has been undertaken since 2001. The geoid model that we are using has been recognized as being fully compatible with modern positioning techniques. We can establish both Vertical and Horizontal Control with centimeter accuracy to meet your timetable demands. For Government Agencies we can help identify where there are areas of concern and establish values for public use.


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