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Updated:
26 March 2008
About Raster
NATMAP digital maps are exact digital copies of Geoscience Australia's NATMAP topographic maps. They cover the whole of Australia at 1:250 000 scale, and are current to December 2004. NATMAP digital maps have a wide variety of professional and recreational uses, including
NATMAP Digital Maps contains all the software needed to use the maps on the Microsoft Windows 98, ME, 2000 or XP operating system and Internet Explorer 5.5 or better (minimum system requirements). Major Features
NATMAP Digital Maps v Raster PremiumIn 2005 two versions of NATMAP Digital Maps were released. The differences are outlined below. As a general rule, where computers meet or exceed the recommended specifications, NATMAP Raster Premium will generally be the first choice.
Contents of NATMAP digital maps(CD-ROM)
Contents of NATMAP Raster Premium (DVD-ROM)
What are the differences between NATMAP Digital Map and NATMAP Raster Premium?
What features have been updated in the 2005 versions?
Are upgrades available for users of previous versions?If you want the updated maps and functionality found in NATMAP Digital Maps, 2005 Release, you will need to buy the new version. No upgrades are available for this product.
What previous releases have there been of this product?
System RequirementsGeoscience Australia provides easy to follow self-help resources for users - this User Guide contains useful trouble shooting tips and a list of frequently asked questions. For troubleshooting advice users are encouraged to seek solutions from the Troubleshooting page. However, if users continue to encounter problems or cannot resolve a problem, Geoscience Australia offers a limited telephone support service for a period of one year from date of purchase for registered products.
If your system does not meet, or is incompatible with, the Minimum or Recommended system requirements described above, you may be unable to operate the Product or experience functional problems when using the Product. In such cases, Geoscience Australia is not required to provide support, advice or assistance of any kind, and Geoscience Australia will not be liable for costs or losses of any kind that you may incur in using the Product. Geoscience Australia is not responsible for maintaining the Product or for updating, modifying or configuring the Product to suit your system requirements. Product ComponentsNATMAP Raster 2005 Release consists of the following components.
Map LayersLandsat 7 Satellite Image of AustraliaLayer Name in the Raster Viewer: "Satellite-Mosaic" The Landsat 7 Picture Mosaic of Australia was produced by the Australian Greenhouse Office (AGO), as part of their National Carbon Accounting System (NCAS), from data acquired by Geoscience Australia in 2001 and 2002. For more information on the Landsat satellite, refer to the Satellite Remote Sensing pages. 1:250 000 scale Topographic Map SeriesLayer Name in the Raster Viewer: "250K-Maps" and "250K-Mosaic" The NATMAP 1:250 000 scale maps included in NATMAP Raster have been produced by Geoscience Australia's National Mapping Division and its predecessor, the Australian Surveying and Land Information Group (AUSLIG), in conjunction with the private sector. This is the largest scale at which published topographic maps cover the entire continent. The maps have been revised using a variety of data sources, including SPOT and Landsat satellite imagery, other government agency information, and data supplied by private companies and individuals. Production of the new NATMAP series began in the early 1990s, and concluded in 2003. This map series continues to be updated. The 250K Maps layer includes individual maps based on the MGA94 projection (GDA94) - on the Premium edition these maps are joined together into a UTM zone mosaic. The 250K Mosaic has all maps joined into a single mosaic based on the Geographic projection (GDA94). For more information on the types of features shown on these maps, please refer to the 1:250 000 scale NATMAP legend explanation. Additional information on map specifications, new maps and the current status of NATMAP revision can be found on the Topographic Mapping pages. 1:1 000 000 scale Topographic Map SeriesLayer Name in the Raster Viewer: "1M-Maps" The International Map of the World (IMW) Australia series was Australia's contribution to a common effort by many international mapping agencies to map the world at 1:1 000 000 scale. It was initially conceived for planning economic development, but has been used as the basis for many other maps including aeronautical charts and thematic mapping. The series was completed in 1978 and was revised regularly until the mid-1980s. Small Scale Reference MapsLayer Name in the Raster Viewer: "5M-Maps" The smaller scale general reference maps provide a general overview of Australia, but still contain similar information to the larger scale maps. These maps have been regularly revised since the mid-1990s, and revision information is sourced from the same sources as the 1:250 000 scale maps. The Locator map used here is derived from GEODATA TOPO-10M, which is freely available from the Geoscience Australia website (requires internet connection). The 1:5 000 000 scale General Reference Map of Australia is used for the 5M Map layer and the Magnifier map. Accuracy and ReliabilityMapsThe 1:250 000 scale map images used in NATMAP Raster are constructed from digital topographic data with a basic horizontal accuracy of approximately +/-140 metres. Therefore, the accuracy of positions reported by the software should approach that of the original paper map. Topographic information included in the map images has been checked from multiple sources including satellite imagery. Most maps have not been field checked, so some information may not be accurate or up to date, especially rapidly changing features such as telecommunication towers and homestead names. Every effort has been made to make the map images a useful reference, but feedback from map users is always valuable. If you discover errors or omissions on the map, please contact Geoscience Australia (mapfeedback@ga.gov.au) or send your annotated Raster printout (showing the map error) to us. The reliability of individual map sheets can be found on the Map Reliability page. Gazetteer data (Place Name Search)The Gazetteer of Australia 2005 Release is a compilation of more than 310,000 geographic names of Australia as of December 2003, provided by members of the Committee for Geographic Names in Australasia. Postcode dataThe postcode information contained in the Place Name Search tool has been reproduced with Australia Post's permission from the Australia Post Postcode Database and has a December 2003 reliability date. GEOMET (ANZLIC Metadata) entriesCreation ProcessThe images used in this version of NATMAP Raster are derived from the most current edition of the respective maps available from Geoscience Australia as at December 2004. "Raw" raster images were created from the digital EPS files used to produce the new NATMAP paper map series. Where digital EPS files were not available, the paper map was scanned to generate the raw raster image. Each raw raster image was transformed to be positionally accurate and encoded with coordinates and projection information before being compressed in the final ECW image. Why are some features not shown on 1:250 000 scale NATMAPs?Some features on maps, especially small scale maps, are subject to what is known as cartographic generalisation. It refers to a group of techniques used by map makers which allow the level of information to be retained, while the amount of data shown on the map is reduced. These techniques include:
More on DisplacementClosely adjacent features may be located on the earth's surface in such a way that they cannot be separated at the scale of the map. To make sure that the map is readable, one feature is kept in its true position, and the rest are displaced. On NATMAP maps, the following list of features may be displaced when one or more are adjacent. The higher a feature is on the list, the more likely that it has been held in the correct position over those lower on the list.
If two features need to be offset relative to one another and neither is listed above, the position of the feature with greater landmark value will be maintained. For example, if a railway and road are coincident at the scale being produced, the road would be displaced. Where two or three features are close and adjacent, one may be displaced by up to 225 metres at 1:250 000 scale. In the worst case when all these features are close together, one may be displaced by up to 675 metres at 1:250 000 scale. However, any features that have been displaced must maintain their relative position. See the image and map area corresponding below. Generalisation is not a completely automatic process and some human judgement is required. Decisions are usually based upon the significance of the feature at the scale of the map being produced, upon the number of similar features nearby, and the purpose of the map itself. One major impact of generalisation is when using maps with global positioning systems (GPS). When a GPS track is overlaid on a map, the track may not match the road as it is shown on the map, because of the displacement described above. This is not an error in the position of the road as such, but one of the consequences of trying to make the map clear and readable. Feature MaskingIf you have a close look at any recent paper NATMAP map you would see that most rivers can be seen "underneath" or "on top of" the roads. The digital process used to manufacture the map images in NATMAP Raster can only show one layer in each pixel (picture element) of the image, hence some features will be masked. The order in which the layering occurs is fixed, and in some maps this may produce some illogical results or effects that will not appear on the paper map. Significant illogical effects (such as canals covering roads) have been edited but may be incomplete. Map Rotation (applies to the "250K-Maps" layer in NATMAP Raster)The map images in this layer appear tilted because they are geo-referenced to the Map Grid of Australia (MGA). Each map's boundaries are based on latitude and longitude, but these boundaries do not always correspond to MGA gridlines. In order to match the map image to MGA, the image has to be rotated and stretched. Note that the blue MGA gridlines on the map are orientated vertically and horizontally in the Viewer, whilst lines of latitude and longitude will be shown at an angle. Join LinesThe Landsat Satellite image is made up of 369 individual images, or scenes. Most of these scenes are cloud free and, in order to achieve this images were taken at different times of the year. Whilst every effort is made to colour match the images, in some cases image matching is not perfect because of differences in ground conditions or time of year that the images were taken. Bleed Edges/OverlapsNew NATMAPs are produced with what is known as a bleed edge. This is the overlap area along the top and right-hand side of the map which allows a map user to overlay neighbouring maps easily. These edges remain in the maps in the "250K Maps" layer, but have been removed in the "250K Mosaic" layer. This was decided upon to reduce processing time and the likelihood of features and text being cut off, and to improve joining. In some cases, this may mean that slightly older information has been retained in these areas; however, this has only occurred in a handful of places around the country. If you notice this problem in a particular area, please let us know about it so we can correct it in future editions. Note on Improving Image ClarityThe map images in NATMAP Raster have been compressed. Images that are compressed have information that has been removed from the image using a particular technique or algorithm to reduce the file size. Depending upon the compression technique, some information may be lost from the image altogether when it is compressed. This is called lossy compression. ECW, JPEG and MrSID are common lossy compression techniques. The images in Raster use ECW compression. This will mean that some features will lose some of their clarity; in particular, very thin lines such as tracks and watercourses may become blurry. Colours may also not be uniform within areas (e.g. forest areas shown as green on the paper map may, on the image, contain traces of other colours). These effects are called artefacts. The resolution or cell size of an image also affects its clarity. Map images with a resolution of 150 dots per inch (dpi) will not be as clear as maps with 200 or 300dpi as there are fewer pixels in each image. As a result, text or other features in map images with lower resolutions will appear pixellated or blocky. Other factors affecting image clarity include your monitor specifications, the software being used to view the map images (if not using the Raster Viewer), and the zoom scale. If viewing in other software packages there is often an option to "zoom to raster resolution"; this zoom level will give the clearest view of the image. Zooming in too far will cause pixellation and artefacts will appear to be very significant; clarity is also reduced if zooming out too far. For best results, you should set your zoom to around the same level as if you were looking at the paper map version at the same viewing distance. Whilst every effort has been made to minimise the number and extent of artefacts within each map image, users should be aware that artefacts exist as a result of fitting all of the NATMAP 1:250 000 scale maps onto minimal digital media at an affordable price. The map images in this product are not intended to be exact replicas of the paper map in terms of quality, but do contain the same information as shown on the paper version. For more information on compression techniques, refer to Image Compression in the ACRES pages on the Geoscience Australia website (requires Internet connection). Map Image SpecificationsFile Naming ConventionAll images in the 250K Maps layer are named according to the alpha-numeric NATMAP 250K map reference system. Where a map does not have a NATMAP 250K map number, such as North West Tasmania, a number has been created. Mosaic or individual map images are named according to scale; that is 250K.ecw, 1M.ecw, 5M.ecw, 20M.ecw. The Landsat 7 satellite image mosaic of Australia is named ls7_mosaic.ecw Positional AccuracyEach identifiable coordinate pixel should be within 4 pixels of the calculated position. The production of maps involves cartographic generalisation of features which adds additional inaccuracies into the images. A full listing of dataset accuracies is provided below.
Pixel SizeThe size of a pixel in metres for any of the Mosaic layers varies with the degree of latitude.
LegendsLegends are included for each of the following scales and images
CD & DVD LAYOUTNATMAP Raster is organised on the media as follows:
Maps labelled * are part of the installation files, and become useable upon installation to your hard drive where they are visible in your chosen installation directory. Maps (except for those labelled * in the table above) are stored in the RastersStandard or RastersPremium folder depending on which version is being used. Within this folder is another folder which is named with the appropriate layer name. See the table below.
NATMAP Raster
NATMAP Raster Premium Conditions of UsePlease refer licence conditions for details of the conditions of use for NATMAP Raster.How to Order NATMAP RasterNATMAP Raster 2005 (GEOCAT No. 61399) and Raster Premium 2005 (GEOCAT No. 61400) are sold through Geoscience Australia's Map Retailers who are located throughout every State and Territory of Australia.You can also purchase over the phone from Geoscience Australia Sales and Distribution, or order online using the following order forms: DisclaimerTopographic information included in the map images have been checked from multiple sources including satellite imagery. Maps have not been field checked and some information may not be accurate. Every effort has been made to make the map images a useful reference.The custodians of the data for the Gazetteer of Australia do not guarantee that the data is free from errors and omissions. |
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