![]() ![]() If the levels on islands closely adjacent to the Australian mainland are observed to standard third order accuracy, and are referred to mean sea level at a satisfactory tide gauge, they are deemed to be part of the Australian Height Datum. Levelling subsequently adjusted to the AHD is called 'Supplementary levelling'. Two-way levelling of third order accuracy or better, used in the original adjustment of which formed the AHD, is called 'Basic levelling'. Mean sea level at both Hobart and Burnie was assigned the value of zero on the AHD (Tasmania). a real or assumed thing, used as a basis for calculations or measurements, as a level (also datum plane) from which elevations and depths are measured in surveying Webster’s New World College Dictionary, 4th Edition. This network, which consists of seventy-two sections between fifty-seven junction points is based on mean sea level for 1972 at the tide gauges at Hobart and Burnie. something known or assumed information from which conclusions can be inferred see also data 2. The levelling network in Tasmania was adjusted on 17 October 1983 to re-establish heights on the Australian Height Datum (Tasmania). With a user-defined datum, you can associate a datum plane or a datum axis with a feature in GD&T Advisor, and then define the targets in Creo as needed. 12, The Adjustment of the Australian Levelling Survey, 1970-71 (2nd edition, 1975). ![]() The datum surface is that which passes through mean sea level at the 30 tide gauges and through points at zero AHD height vertically below the other basic junction points.įurther information on the determination of the AHD is given in Division of National Mapping Technical Report No. The resulting datum surface, with minor modifications in two metropolitan areas, has been termed the Australian Height Datum and was adopted by the National Mapping Council at its twenty-ninth meeting in May 1971 as the datum to which all vertical control for mapping is to be referred. What Are Datums A datum is a plane, a straight line, or a point that is used as a reference when processing a material or measuring the dimensions of a target. Mean sea level for 1966-1968 was assigned a value of 0.000m on the Australian Height Datum (AHD) at 30 tide gauges around the coast of the Australian continent. A datum is defined as follows in the ISO standard: ISO 54592011 One or more situation features of one or more features associated with one or more real integral features selected to define the location or orientation, or both, of a tolerance zone or an ideal feature representing for instance a virtual condition. ![]() Learn the words you need to communicate with confidence. On, Geoscience Australia, on behalf of the National Mapping Council of Australia, carried out a simultaneous adjustment of 97 230 kilometres of two-way levelling. Meaning of datum in English datum noun C science specialized uk / de.tm / us / de.tm / plural data uk / de.t / us / de.t / a single piece of information Want to learn more Improve your vocabulary with English Vocabulary in Use from Cambridge. ![]()
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