Updated:
11 January 2008
Frequently Asked Questions (FAQs)
This page provides answers to commonly asked general questions about our products and services. If you have other queries that are not mentioned here
please contact the Sales Centre. Detailed product related FAQ's exist for a number of our popular products.
About Maps and Data
Q. What scale of topographic maps and data does GA have available?
A. Geoscience Australia (GA) has complete "small scale" reference map coverage at scales of 1:2.5, 5 and
10 and 20 million.
GA maintains a complete national topographic map and data coverage at 1:1 million and 1:250,000 scale.
GA has an incomplete map and data coverage at 1:100,000 and 1:50,000 scales.
| Map/Data Scale |
Scale Description |
Example Uses |
Map/Data Producer |
| Small Scale (1:1 to 10 million) |
State, National and International |
General Reference, Tourist Maps |
Geoscience Australia |
| 1:250,000 (1cm = 2.5 km) |
Regional Scale |
4 Wheel Driving (4WD), Route Planning, GPS Navigation, Mineral Exploration, Environmental Planning |
Geoscience Australia |
| 1:100,000 (1cm = 1 km) |
Regional Scale |
Emergency Response, Planning, GPS Navigation |
Geoscience Australia
State Mapping Agencies - limited coverage.
|
| 1:50,000 (1cm = 0.5 km) |
Local Scale |
Bushwalking, Fauna Surveys |
Geoscience Australia - limited coverage mainly over Northern Australia.
State Mapping Agencies - limited coverage.
|
| 1:25,000 (1cm = 0.25 km) |
Local Scale |
Bushwalking, In-Car navigation, Environmental Impact Assessment |
State Mapping Agencies - variable coverage generally over the more populated areas.
|
Q. I am after other types of maps and data - where can I find these?
A. GA often receives requests for other types of maps and data - a list of the most commonly requested types and where they can be obtained is detailed below:
Q. How do I find maps or data over my area of interest?
A. For both Maps and Data (produced by GA):
Use GA's online interface to our products database (GeoCat) - this allows you to locate any products
produced by GA, either by way of a text based search or
map based search. Alternatively, you can use our place name search.
For Maps Only:
Use GA's paper Map Index - two separate indexes are
available for GA's maps, one for our 1:50,000 maps, and the other for 1:100,000 & 1: 250,000 maps. These free indexes
can be obtained from NATMAP Retailers or from the GA
Sales Centre.
For Maps produced by all government mapping agencies:
Intergovernmental Committee on Surveying and Mapping (ICSM) Australian Topographic Map Index - this
is an online index to all Australian topographic maps (both Commonwealth and State).
Q. How can I find out when GA's topographic maps are going to be updated?
A. See information on our Upcoming Maps.
Q. How does the map numbering system work?
A. Standard topographic maps are numbered according to a system developed for the International Map of the World.
Q. What can I do if I find an error in your Maps or Data?
A. Please let us know about it! Such information is a valuable tool in improving our maps
and data. Please email our map revision team at mapfeedback@ga.gov.au.
Q. What is the International Map of the World?
A. The International Map of the World (IMW) was a small scale topographic map series at 1:1,000,000 scale published by a number
of countries to common internationally agreed specifications, and was originally conceived in 1891 at the Fifth International
Geographical Conference as a tool for planning economic development. In 1926 the Australian component was begun and by 1939 one quarter of Australia had been mapped
at this scale. The United Nations took over the project in 1953; however, international interest waned and by the 1980s
only 800-1000 of the proposed 2500 maps were completed. The project was abandoned by the mid-1980s.
The Australian component was completed in 1978 and revised up until the mid-1980s. Geoscience Australia now contributes to the Global Map project which in effect has superseded the International Map of the World.
Further information on the International Map of the World can be found on the
National Library of Australia website and
the Geography Home Page.
About Mapping
Q. What is the difference between the GIS data and the corresponding digital maps?
A. GIS data is used to produce both digital and paper maps - the underlying data is identical. GIS data is supplied in vector format - as opposed to raster format. Vector data uses geometric objects (points, lines or polygons) to depict spatial information. For example, linear features like roads and railways are depicted as lines. The raster data model represents geographical space by dividing it in a series of cells. The further you zoom in the more obvious the "cells" (also known as pixels) become.
Raster data is available as printed paper maps, or on digital media (CD Rom or DVD Rom).
Sample Raster Data
![Click to view larger sample raster data [JPG 101Kb]](/servlet/BigObjFileManager?bigobjid=GA2578) |
Sample Vector Data
![Click to view larger sample vector data [JPG 99Kb]](/servlet/BigObjFileManager?bigobjid=GA2580)
|
Q. What are Projections and Datums?
A. Projections are ways of allowing us to display a round 3-Dimensional Earth onto a flat 2-Dimensional Map. A Datum is a framework that enables us to define a co-ordinate systems. Please follow the link for further information on projections and datums.
Q. What is GDA94?
A. GDA94 stands for Geocentric Datum of Australia 1994. GDA94 is the new Australian coordinate system, replacing the Australian Geodetic Datum (AGD).
GDA is part of a global coordinate reference frame and is directly compatible with Global Positioning Systems (GPS). The Intergovernmental Committee
on Surveying and Mapping (ICSM) maintains a page with detailed information on GDA94.
About Place Name Search/Gazetteer Questions
Q. I have found a possible error in the Place Name Search ? (the name is misspelt or the co-ordinates appear wrong)
A. Send us an email (gazetteer@ga.gov.au), describing the problem you have found. We will investigate the problem, and if an error is confirmed we will advise the relevant data custodian.
About Aerial Photography
Q. How do I select Aerial Photography over my area of interest?
A. Aerial Photography is recorded on flight line diagrams which show aircraft paths, search our online flightline diagrams.
Q. How do I purchase Aerial Photography?
A. Select aerial photography from flight line diagrams then contact United Photo and Graphic Service Pty Ltd (UPGS)
About Remote Sensing
Q. What sensors does Geoscience Australia collect imagery from?
A. A full list can be found in the Satellite Facts section of Geoscience Australia's website.
Q. What does 'pixel size' refer to?
A. A pixel refers to smallest building blocks of electronic elements which can be
displayed on a screen, and is usually referred as a unit of measurement for image size and resolution.
The width and height of an image defines the pixel size and the ability to resolve features on the
image, e.g. a pixel size of 25 metres means each pixel on the image is 25 metres on the ground.
Q. What does 'spectral band' refer to?
A. Band is a wavelength interval in the electromagnetic spectrum in which data is
captured by a satellite sensor. For example, the Landsat 7 sensor provides information on the Earth's
surface in the visible, near, middle and thermal infrared regions of the electromagnetic spectrum.
Q. What does 'ortho-corrected' mean?
A. Rectification is the process by which an image is
converted from image coordinates to real-world coordinates using ground control points (GCPs). The ortho-correction process corrects
errors that are introduced due to the shape of the terrain. This can be done through the use of a
Digital Elevation Model (DEM), sometimes referred to as Digital Terrain Model (DTM).
Links to Specific Product FAQs
Some of our products & services have additional detailed FAQ pages to assist users. These pages
provide detailed assistance with issues directly related to a particular product. Links to these
pages are provided below:
Q. Where can I buy the NATMAP Raster product?
A. NATMAP Raster products on CD and DVD can be obtained from both the Geoscience Australia Sales Centre or your nearest map retailer.
Links to State & Territory Mapping Agencies
