Remote sensing plays a key role in the mapping of the Australian continent. Frequently it has been the only practical means to achieve the speed and detail necessary to explore such a rugged and underpopulated country.
Australia's remote sensing industry, in both private and government sectors, is application oriented. It has readily embraced new and improved technologies, making notable contributions in many areas.
This is a natural consequence both of the shape of our economy, and the environment on which it all depends.
Australia is huge. The sixth largest country in the world, its land covers 7.6 million square kilometres. The Exclusive Economic Zone encloses another 8.1 million square kilometres. Australia has control of a total area of 15.7 million square kilometres, which is a large portion of the Earth's surface.
On the other hand, it has barely 20 million people; the continent lacks sufficient water for more. Not only does it have low average rainfall --165mm per annum on average - but what rain there is tends to fall in the tropics. There is little over vast areas of the arid core. More than a third of the continent is effectively desert.
The upside of this is that for much of the year, many parts of Australia are relatively cloud free, providing excellent conditions for satellite remote sensing.
Another plus follows from the fact that Australia has the most ancient exposed regolith on Earth. It is massively eroded and flat in world terms. This relative flatness benefits remote sensors as images show very little topographic height distortion effects.
Moreover, because of the ancient erosion, much mineral wealth has been exposed, particular in the arid centre where there are few forests to interfere with ground reflectance.
Australia is extremely well endowed with most minerals and fossil fuels (with oil being the notable exception), and has barely scratched the surface of its mineral resources. The nation holds the world's largest known economic resources of bauxite, iron ore, lead, zinc, silver, uranium, industrial diamonds and mineral sands.
Success in uncovering new deposits can be attributed to recent advances in prospecting technology, including remote sensing.
Remote sensing works in Australia because it's dry; paradoxically, it also works where it's wet. The Great Barrier Reef extends for 2000 kilometres down the north-east coast of Australia. It accounts for nearly one fifth of the world's reef areas. Its management requires extensive use of remote sensing.
Even outside the reef, there is a vast area of ocean, along with the fishery, mineral, and petroleum resources found in or under it. The management and protection of the waters that yield these resources is, however, a complex task.
Remote sensing also plays a significant role in forestry and agriculture. The future of these industries lies in sustainable water management strategies, and on combating dryland salinity and drought.
The management of forests in general, the increasing development of plantation forests, and the control of both legal and illegal clearing of forests for farmland has made remote sensing an important tool. It is valuable in both the production and conservation of forests, and for estimating biomass and its change on a continental scale.
Another paradox of remote sensing in Australia is that despite the country's small population, it has two dense urban regions. Nearly half its people live in either Sydney or Melbourne. Because of this, there is extensive remote sensing of urban areas.
All this means that the natural characteristics of Australia make it an ideal subject for the use of remote sensing as a mapping, monitoring and management tool.
The industry that supplies and uses the data can be divided into government, research and private sectors.
The government sector comprises state and federal jurisdictions. The Australian Centre for Remote Sensing is Australia's major satellite remote sensing organisation. It is the largest federal government unit, and the largest centre of remote sensing expertise in the country.
It was established as the Australian Landsat Station in 1979. It still maintains an archive of land cover from that time.
It holds data from Landsat 7 ETM+; Landsat 5 TM; Landsat MSS; ASTER; ERS-1; and JERS 1 SAR. ALOS will be available in late 2006 for the Oceania/ Pacific region.
At the state level, remote sensing applications include agriculture, geology, disaster monitoring, oceanography, land management, surveying and cartography, and meteorology. State jurisdictions also carry out environmental monitoring, as well as urban mapping, monitoring and planning.
The centrepiece of the research sector in Australia is the CSIRO. Its work is aimed at delivering solutions for agribusiness, energy and transport, environment and natural resources, health, information technology, telecommunications, manufacturing and mineral resources.
The CSIRO also works at the forefront of emerging sectors, such as information and communication technologies, gene technology and nano-technology.
A number of CSIRO divisions undertake research in the field. These include Marine Research, Land and Water, Mathematical and Information Science, Sustainable Ecosytems, Forestry and Forestry Products, and Exploration and Mining.
The technology is also a focus of a wide range of research for the Defence Science and Technology Organisation.
It has developed an airborne X-band synthetic aperture radar and recently entered into an agreement to build a new airborne/ground, mapping/imaging radar system unique to Australia. Under the agreement, the existing DSTO airborne X band synthetic aperture radar will be enhanced with the addition of a high fidelity L-Band mapping capability.
The upgraded system will have both enhanced defence and civilian applications. These include the ability to map soil salinity, terrain/elevation types, bushfires, floods and oil spills, during day or night and in all weather.
There is also an active research sector in universities. One of the most spectacular recent projects was the Pacrim 2000 mission, involving CSIRO, NASA and the University of NSW. Access to Pacrim data can be obtained from Professor Tony Milne.
The federal government has set four national research priorities. The first of these is an Environmentally Sustainable Australia. Its goals include: sustainable water use; overcoming soil loss, salinity and acidity; responding to climate change and variability; and sustainable use of Australia's biodiversity.
Central to all of these is the use of remote sensing for monitoring and modelling. For example, the National Carbon Accounting System - part of the Australian Greenhouse Office - provides information on land-based sources and sinks of greenhouse gases. This data is needed to fulfil international reporting obligations under the Kyoto Protocol, and to provide annual estimates to Australia's National Greenhouse Gas Inventory.
The private sector encompasses many types of organisations with a variety of capabilities. One group consists of distributors and agents for both ACRES data, plus various satellite data acquired and processed in other countries. On this basis, Australian users can gain access to data from Spot, Ikonos, Quickbird and others.
Following the world pattern, airborne remote sensing in Australia is currently going through a period of great change. The influx of new digital airborne sensors represents an exciting transition from analogue to digital data capture. In the past twelve months, many new sensors have emerged. It is now possible that there could be up to three Vexcel Ultracams, an Intergraph Digital Mapping Camera and a Leica ADS- 40 three-line scanner, all operating in Australia at the same time.
Other interesting sensors also operate regularly in Australia, notably a hyperspectral line scanner and two airborne laser scanners. The Hymap sensor acquires data in 126 bands between 0.45 um to 2.5 um. It is therefore ideally suited to many applications, including vegetation studies and mineral exploration.
Airborne laser scanning has also been a feature of the Australian airborne scene for many years. At least two laser scanners are currently carrying out regular work in Australia - a Leica ALS- 50 and an Optech ALTM system.
The environmental sector provides the bulk of the work for many companies. They create large databases and provide consultancy services, for example, in precision agriculture and forestry.
While these large systems have their place in the industry, many people, especially university research groups, are beginning to see the benefits of small format imaging systems. As yet, there are comparatively few small format operators in the Australian market, but as end users begin to realise the potential of small format data, we are likely to see the emergence of many more.
Recent advances in digital camera technology mean that data from small format systems is in fact incredibly good, both spectrally and geometrically.
The result is an industry that is tightly coupled to Australia's economic needs. Its future is guaranteed because it now forms part of any recipe for a sustainable future for Australia. It will also continue to be a major contributor to national wealth.
Bruce Forster is a visiting professor in the School of Surveying and Land Information Systems at the University of New South Wales; Paul Dare is the director of Spatial Scientific Technologies and Chair of the Remote Sensing and Photogrammetry Commission of the Spatial Sciences Institute; Simon Jones is an associate professor in the School of Mathematical and Geospatial Sciences at RMIT University. This is an edited version of an article that first appeared in the Asian Journal of Geoinformatics, Vol. 6, No. 2 (2006).
