The National Mapping Council of Australia Standards of Map Accuracy (2nd edition, 1975) stated in general terms that, 90% of tested contours and elevations interpolated from contours will be accurate to within one half a contour interval of their true height. Not more than 10% of well-defined features are in error by more than 5600 metres.Not more than 10% of well-defined features are in error by more than 2800 metresĪt 1:10 000 000 scale, the summation of errors from all sources results in map detail with a standard deviation of 3400 metres for well-defined features.Not more than 10% of well-defined features are in error by more than 1400 metresĪt 1:5 000 000 scale, the summation of errors from all sources results in map detail with a standard deviation of 1700 metres for well-defined features.General Reference maps will have no statement of map accuracy on the map layout however they must comply with the following statements of planimetric accuracy:Īt 1:2 500 000 scale, the summation of errors from all sources results in map detail with a standard deviation of 850 metres for well-defined features. Not more than 10% of well-defined features are in error by more than 140 metres.Not more than 10% of well-defined features are in error by more than 56 metresĪt 1:250 000 scale, the summation of errors from all sources results in map detail with a standard deviation of 85 metres for well-defined features.NTMS maps will comply with the following statements of planimetric accuracy:Īt 1:100 000 scale, the summation of errors from all sources results in map detail with a standard deviation of 34 metres for well-defined features.Īn alternative and equal way of expressing this error is: Geoscience Australia restricts its statements of Topographic Map Accuracy to well defined points. While Geoscience Australia's positional accuracy measurements for topographic data are given to encompass a feature's entire spatial representation. Geoscience Australia has carried out both error analysis and field tests to verify the positional accuracy of features on the existing mapping. Most commonly the well-defined points used in tests are at feature intersections. The term 'well-defined points' is used to define those locations which can be accurately identified on the map. The measure of accuracy given for topographic maps is the standard deviation. The use of a 'cartographic representation' of a feature maintained in its 'true position'. This error is applicable when the process of generalisation is independent from the source data capture/maintenance process. The errors inherent in the process of generalisation of the above data that forms part of the map production process. The positional accuracy of the digital data used in the map production process (see Section 1 Chapter 3.7 Positional Accuracy).The error in the position of a feature results from: The positional accuracy of features on a map is an estimate of the degree to which the coordinates of that feature agree with the true values or values accepted as being true. Generalisation, although necessary in derived products, must be kept to a minimum. Thus the map maker must exercise maximum care in ensuring that the detail plotted is complete, correctly classified and portrayed with shapeįidelity. To the map user, the quality and completeness of the information is of prime importance and may take precedence over absolute positional accuracy. The term may also describe the quality and completeness of the information shown on a map. The term 'map accuracy' refers to the positional and vertical accuracy of information contained within the map. Detail is systematically plotted to scale on a selected map projection to present the horizontal and vertical position of topographic features in an identifiable and measurable form. The topographic map is a graphic representation of a portion of the earth's surface generalised to allow significant detail to be shown with clarity and without ambiguity. It includes the relevant standards expected for map accuracy, datum control, map generalisation principles, map symbology and masking rules, type selection and placement rules, type (font & size) specification and standard type abbreviations.Ĭonformance to these specifications will assure uniformity through all mapping elements and agencies engaged in the production and maintenance programs for these series. This document provides the rules and guidelines for the generation of the Geoscience Australia 1:100 000 and 1:250 000 National Topographic Map Series products as well as smaller scale General Reference Map (eg 1:2 500 000) products.
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