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GIS Datasets
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Updated: 13 Jan 2004 Frequently Asked Questions (FAQ): Digital Data ProductsThe following questions and answers relate to digital data products produced by the National Mapping Division of Geoscience Australia (GA). Questions and answers will be progressively added to this page to assist users with most of their general queries.
Q. Why is the datum of data in GDA94 not recognised by MapInfo? A. This is relevant to users who have downloaded the mid/mif (MapInfo) files of the online products with a datum of Geocentric Datum of Australia 1994 (GDA94). For some files, the datum is not defined in the 'mif' file header which causes MapInfo to read the datum as 'Non-Earth' as opposed to GDA94. Even though the datum is not defined, the data is in GDA94 and will project properly in MapInfo. We are aware of the confusion this can cause and are looking into correcting it for future data. However, if you would like to correct the files so the datum is recognised by your MapInfo software, then you can use a text editor to change the following part of the header in the mif file so that it reads as set out below: DELIMITER "," Please make sure that the coordinates after 'Bounds' are the same as those in the original mif file. Also, please note that these are the projection details for the World Geodetic System 1994 (WGS84). This is similar to GDA94 but more widely compatible with older versions of MapInfo. Download a PDF version of ICSM's paper ["What is the difference between WGS84 and GDA94?"' PDF 30KB (Get PDF Reader)] which contains more information on these differences. Q. I have downloaded some free data from your site - what software can I use to view it? A. All datasets are available in the following GIS formats: The above formats are compatible with a wide range of professional GIS and Image Processing softwares (eg. MapInfo Professional, ESRI ArcGIS, RSI's ENVI). If you do not have access to this sort of software, there is a range of free GIS viewing software that will enable you to view the data (see list below). Please be aware that these programs have limited functionality, and it is recommended that you have some familiarity with GIS before attempting to use them. They are also quite large downloads (approximately 10-20Mb in size). Additionally, a number of widely used GPS Mapping programs (such as OziExplorer) can import our GIS data. Geoscience Australia (GA) does not endorse or offer any support for the following viewing software - you will need to contact the respective software developers.
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