In any emergency situation, lack of information makes it difficult for those in charge to make informed decisions. Bushfire fighting is no different - and the information provided by aerial observations is crucial.
Aerial observations, especially video and high-quality infrared imagery - which is fully integrated with GPS and linked to GIS software - can provide answers to a number of questions asked by firefighters. The infrared imagery is especially important. By their nature, bushfires are hot, and covered in smoke. But smoke is transparent at infrared wavelengths, and an infrared image is a map of temperature as much as anything else. Thus an infrared sensor can map the actual position of the hotspot, not just the location of the smoke plume.
The infrared sensor is mounted on a helicopter: - Photo supplied by South Pacific Science Press
But no matter how it is done, there is a time lag between the acquisition of imagery and its display to fire controllers. Most of the technology effort in mapping circles at the moment is focused on reducing or eliminating this problem. We need to be able to provide real-time data so firefighters can see what is happening now, not what happened yesterday.
An infrared sensor can map the position of the hotspot, not just the location of the smoke ... It is important to recognise that the provision of spatial data to firefighters is already technologically very sophisticated. The remote sensing and data-capturing technology used by our bushfire organisations has evolved over recent years into some of the best in the world. This is consistent with the impact that bushfires have on Australian society.
Infrared cameras and scanners have been around for a number of years. So has GPS. Frequently, helicopters have been used to map out fire-fronts by tracking their position with GPS while flying over the front. In both cases, the electronic information is used to create hard copy, which is then passed on to bushfire management centres with the lines marked on transparencies so it can be physically overlaid on a map.
More recently, effort has been put into providing the location information to firefighters in electronic form, so that it can be downloaded directly into electronic cartographic systems. This can be achieved by integrating the infrared camera and the GPS and providing the output in a standardised format which can be read by the GIS.
The GIS can then be used to add considerable value to the information. For instance, the incident management team needs to know exactly where each fire or outbreak is in relation to the landscape around it. Is it near housing, fences, rivers, roads, cliffs or other features? The slope of the landform is also important to firefighters. A fire's speed doubles for every degree of up slope - the greater the angle, the faster the fire will move.
The map of the fire front, the digital video and the infrared video all provide good data for the firefighters. When all these are integrated, controllers are able to see where the fire front is on the map, how it looks on the video, the hot spots and threats from the infrared video - all on the one laptop screen. They can click on any part of the fire track and the video will automatically fast forward or rewind to the correct part of the tape to show the appropriate pictures. When viewing the tape, the tracking line on the map follows the tape.
Currently, this information is provided to the Rural Fire Service (RFS) in 'near real time'. The helicopter will fly a sortie, record all the data, land and then review the video and track with the ground team. At best, the data is five minutes out of date, and at worst, one hour - the tapes used are an hour long.
Now the challenge is to provide the same data in real time. Three Sydney companies - Gyrovision, Sydney Helicopters and Lateral Linking - have been working with the NSW RFS to try to come up with a better system. The companies have pooled their resources and have created a system that will allow information to be downloaded to the ground in real time. This increases the speed at which decisions and reactions surrounding critical incidents can be made.
The video and GPS data streams are downloaded by way of radio link to a receiving station on the ground. The link needs to operate in line-of-sight, so the receiving station needs to be set up near the fire front. From the receiving station, the signal would usually be relayed in some way back to the control centre.
The management team needs to know exactly where each fire is ...
The radio link uses technology provided by Lateral Linking, which specialises in the provision of television links for broadcast television. For TV use, it is quite common to relay the signal via another aircraft high in the sky, and thus to link with a permanent ground station. In NSW, it would be possible to use this methodology to provide coverage within 100 km or so of Sydney.
Alternatively, an incident management team could be sent to the location, and the fire could then be managed from some appropriate location within range of the helicopter.
A third alternative might be to use some form of long-distance relay, such as a satellite link, to link a portable ground station to the permanent control rooms.
During the last northern summer, fire crews in the US used a similar system. In that system, helicopter-borne sensors were radio-linked back to a mobile GIS laboratory on the ground.
Essentially, this was just a computing unit mounted in a container on the back of a truck. Whichever relay method is used, the signal is sent to the lab, where GIS operators interpret the data and provide bushfire personnel with the maps.
The infrared sensor control unit in the helicopter. The sensor can be panned, tilted and zoomed from here, and output can be taped to provide an independent record of the operation. The transmitter is located on one of the landing struts of the helicopter: - Photo supplied by South Pacific Science Press
The camera, which is provided by Gyrovision, is a scientific-grade thermographic camera on a gyro-stabilised platform. The settings on the camera can be customised to pick up particular ranges of temperature, and are sensitive to within 0.15 degrees. The radiometric system provides precise digital temperature information (minimum, maximum and average). The information can be of spot or area locations and is not affected by ambient surface temperatures. This is accomplished by inputting several kinds of additional data - emissivity, atmospheric temperature, ambient temperature, objective distance, relative humidity, computed transmittance and estimated transmittance - and manipulating the data to arrive at readings which use the surface temperature as the base temperature.
A synchronised digital video image is recorded along with the temperature readings. This provides quality digital imagery in addition to the thermal readings. The imagery is recorded with the same field of view as the thermal readings, imprinted with GPS co-ordinates, and time encoded for frame grabbing. This gives the incident command team yet another tool.
The new equipment was demonstrated to fire officials at a meeting at the Sydney helicopter centre in November 2003. Two messages emerged from the meeting. One was certainly that the technology works. But the other was that the critical issues in deploying the technology are not technical: they have to do with economics and organisation.
This set-up was used during a recent demonstration to fire chiefs at Rose Hill. Data is received, recorded and displayed. In practice, this equipment could be deployed in the field, or a long-range link could be provided: - Photo supplied by South Pacific Science Press
For instance, it is possible to use the technology to centralise control of fire-fighting at the RFS headquarters. It is also possible to put the technology in the hands of local operators. The RFS is currently trying to decide which is preferable.
Despite such concerns, the bottom line is that real-time coverage of fire fronts is now a reality, and it is a significant new tool in command and control for fighting fires. We need all the help we can get.
