This programme provides the facility of locating a set of the nearest Trigonometrical Beacons and/or Town Survey Marks (TSMs) to a User defined geographical position.These files, if required, will be transformed using the same Control files and Options as set for the Co-ordinate file. Finally, the programme provides the facility of transforming any other related files such as Tacheometric files, Contour Files, DTM files and Centre Line files.If required, any associated CAD file will be transformed, using the same Control files and Options as set for the Co-ordinate file. Once the “Source File” has been selected, the programme will search for the existence of any associated CAD files such as General Plans, Working Plans, Sectional Title Sheets and CAD Plot files, that may also need to be transformed.This number of selected control Points can vary between 2 and 20. The User selects the number of the nearest common control Points to be used for each Point to be transformed. The Search Limit to be used when the programme is requested to search for the nearest group of Stations to the current point.The type of Weighting required (None, Inverse Distance or Inverse Distance Squared).The User selects settings from a number of offered options, namely : Due to the nature of the re-adjustment of the Hartebeesthoek94 co-ordinates using a transformation based on a table of adjustments, or parameters, for a given area cannot provide the same level of accuracy as that of a Weighted Helmert transformation that uses the 4 or 5 closest common Control Points lying around to the Point being transformed.This programme should not, therefore, be confused with other programmes that offer only approximate (0.50m – 1.50m) transformations for the purpose of small scale mapping, or non-survey related activities. Accuracies in high density urban areas tend to be higher, due to the larger number of common Points in these areas. Tests have shown that typical Standard Deviations resulting from transformations vary between 0.01m and 0.07m.Where we have a large number of common control Points (38,000) the transformations are extremely localized and provide the highest accuracy of transformation possible between the two Ellipsoids. This programme is designed to satisfy the requirements of Land Surveyors, Mine Surveyors and Engineering Surveyors requiring high accuracy transformations (The transformation carried out is by using either a Weighted Helmert transformation, or a Standard (non-weighted) Helmert transformation, with a User determined number of common control Points.These data may be contained in a SURPAC Co-ordinate file, an ASCII Co-ordinate file, an ASCII file or be written data that are to be entered manually. To carry out a transformation, it is only necessary to have co-ordinate, or Geographical, data related to one of the two Ellipsoids, and lying within the geographical boundaries of the specific country.
In other countries, we have attempted to have as many Control Points as we can lay our hands on.
Universal Transverse Mercator, U.T.M., using Various Ellipsoids.Irish National Grid using the Airy 1830 (Modified) Ellipsoid,.National GPS Network, ETRS89, using the WGS 84 (GRS80) Ellipsoid, National Grid System, OSGB36, using the Airy 1830 Ellipsoid, Namibian “Bessel” System using the Bessel 1841 Ellipsoid (GL Metres and Int.South African “WG” System using the WGS 84 Ellipsoid,.Various Southern African “Lo” Systems using the Clarke 1880 (Modified) Ellipsoid,.This set of Transformation programmes supports the following Systems and/or Ellipsoids :.
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