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Drones are revolutionising environmental science. Four scientists explain how they are using drones, what challenges they face and how the technology is changing our understanding of the world around us.

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Sixteen years ago, when Dr Karen Joyce was a PhD student, she dreamed of having a helicopter to help her map coral on the Great Barrier Reef.

"We were doing a lot of work on the reef taking our equipment out in small towed boxes and walking around the coral," says Dr Joyce, a geographer at James Cook University.

"It's quite challenging to look at the reef like that and you can only look at really small areas.

"I thought it would be fabulous to have something you could hover above the reef from about 20 metres and take the measurements from that height and that perspective."

Drone technology was first developed for the military. And it is here, while working for the army in 2004, that Dr Joyce first saw the potential of using drones for science.

"They couldn't understand why I would want to use [a camera that looked down at the ground instead of forward at a target]. But it sort of got me thinking ... this would be quite a cool technology to try to bring across into research and the academic world," she says.

However, she says drone technology did not become widely available until around 2010 when prices started to come down, cameras got smaller and started appearing on smartphones, and battery technologies improved.

"I could see the progression of the technology and I really started to think this now might be something that was within reach for us," she says.

Today, drone technology is revolutionising environmental science.

Scientists, like Dr Joyce, are using drones for a diverse range of purposes such as mapping remote environments, monitoring agricultural crops, tracking wildlife, identifying biosecurity threats and distinguishing features in the landscape such as craters or erosion.

The technology is now so cheap that small drones have become ubiquitous tools for taking aerial photographs — a trend that is likely to explode later this year when licensing regulations are relaxed for craft under 2 kilograms.

But scientists do more than take pretty pictures with drones. And with the added complexity comes technical and ethical challenges.

Mapping coral reefs and mangroves

Share Image of coral and algae in the Great Barrier Reef taken using a standard DSLR camera shows patches of live coral (pink) and algae (green)

Dr Joyce is currently using drones to monitor and map the health of coral reefs and water circulation in the Great Barrier Reef, and mangrove forests and water quality in Darwin Harbour.

She uses data collected from the drones to calibrate satellite data, information captured by ecologists on the ground and colleagues using underwater robots.

"[Drones] can get over the top of what you're looking at, they can generally get further as well," she says.

"So you don't need to walk through the mangroves or worry about crocodiles or tread on coral."

"Whereas a satellite might be able to tell you the forest is there, the drone will be able to look at individual trees and leaves as well."

"So they give you a different scale to a satellite, but they still give you same perspective as they are overhead and still looking down."

Share Researcher Dr Karen Joyce says drones are quickly superseded by newer models.

Her equipment ranges from a couple of small off-the-shelf multi-rotor drones that cost between $500 to $1,000, which can carry a small digital camera or sensors, to a large 35-kilogram custom-built drone.

The Great Gazoo is a $70,000 craft that can carry up to 15 kilograms of equipment that can include digital camera and a range of specialised sensors such as a hyperspectral camera, which can analyse changes in vegetation from the light reflected off the surface of the plant, and thermal camera, which measures temperature.

"Thermal cameras have only just become small enough to be able to put on drones. This is super exciting for the work that we do," Dr Joyce says.

"If we can understand a bit more about what's happening about water temperature and how it's moving around the reef then we might be able to assist with modelling and management of those processes."

Monitoring ice sheets

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For the past two years, polar oceanographer Dr Guy Williams has been using drones in Antarctica and the Arctic to measure changes in sea ice.

"Sea ice is a sensitive indicator of change in both the atmosphere and ocean. By studying sea ice behaviour, we can better understand the underlying forces responsible in the climate," says Dr Williams of the University of Tasmania.

Dr Williams uses drones fitted with digital SLR cameras to calibrate information from satellites, including Cryosat-11 and the next generation of polar satellites IceSat-II, and data from underwater robots.

"Getting sea ice thickness from space is challenging, due to the complex material nature of sea ice that often includes a separate layer of snow on top," Dr Williams says.

Share Dr Guy Williams launches a fixed-wing drone in the Arctic

Dr Williams' team fly multi-rotor and fixed-wing drones.

"The multi-rotors can operate at extended ranges (2 kilometres) and altitudes (500 metres) away from the ship, returning live video and the ability to conduct autonomous mapping missions," he says.

"The fixed-wings provide much greater flight endurance and range, but come with additional challenges with respect to launch and recovery from an icebreaker."

He says Antarctica provides unique challenges for operating drones.

"Antarctica is a special, protected area and so there are extra concerns with respect to the safe operation of drones and the potential impact a crash might have on the environment, fauna and flora," Dr Williams says.

Proximity to the south magnetic pole can affect multi-rotors, which rely heavily on the compass and magnometer for navigation.

This is not a problem for fixed-wing craft that navigate solely on GPS.

Wind and ice are other factors.

"Once below -10 to -15 [degrees] Celsius, all bets are off with respect to the material strength and effectiveness of plastics, rubber, metal and lubricants."

Wildlife conservation

Conservation ecologist Associate Professor Lian Pin Koh built his first prototype drone in 2012 to fly over the nests of orangutans in Indonesia.

"We believe drones have potential not only for combating wildlife crime but also for monitoring the health of wildlife populations," says Dr Koh in a TEDtalk about his work as a director of not-for profit organisation ConservationDrones.org.

Today he is the director of the Unmanned Research Aircraft Facility at the University of Adelaide, where he and his team use drones to track wildlife, including yellow-footed wallabies, bettongs, and birds, as well as map how forests regenerate following bushfires.

The yellow-footed wallaby project in the Flinders Ranges uses thermoimaging cameras attached to a quadcopter to track heat signals given off by the animals.

"We are trying to cover a larger area than possible with conventional ground-based techniques, such as driving in a ute or hiking through the bush on foot," Dr Koh says.

The drone allows the team to cover one to 2 kilometres within 10 minutes.

"Researchers have also been flying manned aircraft to try and look for these animals. That is still very useful but very expensive."

However, he says while drones can help researchers track animals, little is known about the impact on the animals themselves.

A recent study in the US showed drones increased the heart rate of bears. In Australia, drone operators often report attacks by wedge-tail eagles.

"There are more and more biologists using drones and nobody really knows if they are causing harm to the animals," Dr Koh says.

One of Dr Koh's students, Jarrod Hodgson, who has used drones to study bird populations, is now trying to answer this question.

"There are very few such studies around and we think they are very important and we are trying to repeat [the bear study] on birds in Australia to try to see if we can develop better guidelines for using drones to study animals."

Monitoring crops and forests

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Geographer Arko Lucieer first used drones — a $1,000 remote controlled helicopter with a camera attached — to study the impact of rabbits on Macquarie Island in 2009.

"We were using very expensive high-resolution commercial satellite imagery for that task," says Dr Lucieer, an Associate Professor at the University of Tasmania.

"What we found is that we really wanted to get higher resolution imagery and we wanted to better understand what was in these satellite pixels."

He went on to use the same technology to study moss to look for signs of climate change in Antarctica.

"The mosses there are so fragmented in the landscape ... that is very difficult to observe with satellite imagery, so again we felt that there was this scale niche where satellite imagery wasn't detailed enough."

Today, armed with even more sophisticated technology, Dr Lucieer and his team study the health of forests and crops, such as vineyards and opium poppies in Tasmania.

Share Multi-rotor drone carrying the multispectral camera that took the image below.

The team use modified fixed-wing and multi-rotor drones — including a 13-kilogram craft called The Devourer — fitted with custom-made sensors that detect light points, airborne lasers and global positioning systems to identify plants and the 3D structure of forests and crops.

"We're one of the first teams in the world to have developed a multi-rotor drone with a laser scanner and were using that in pine and eucalypt plantations to get very dense point clouds off forestry plots," says Dr Lucieer.

"At moment they send out field teams into these plots to measure every single tree.

"It's very laborious, very time consuming, can be dangerous and often difficult to get to these plots so we're now working on a project to see if we can complement or partly replace some of that human effort."

More than pretty pictures

Share Image of eucalyptus trees and shrubs taken by a multispectral camera. Subtle difference in colour indicate tree height and/or health. For example, the bright red colour is indicative of healthy vegetation.

Once data is collected it is put through software that matches geolocations on each frame to create mosaics made of up of multiple images or 3D maps.

However, some scientists are concerned about the quality of data being collected.

"A lot of people are jumping on the drone bandwagon because they're the sexy new tools that people think can provide us with a lot of valuable data," says Dr Lucieer.

"Drones are an ideal platform to capture images at very high resolution but to actually generate valuable data products for ecologists or natural resource managers is still challenging."

In part this comes down to how different types of scientists work together, says Dr Lucieer.

Scientific sensors Five main types of sensors Standard digital camera — which can be used to simply identify that an animal or plant is present in an area or used to create mosaics and 3D maps.

Thermal cameras — which use wavelengths to detect heat signals off objects such as animals, stressed plants and water.

Hyperspectral — which measures reflected light in hundreds of wavelengths. This can be used to identify different features of plant and water quality.

Multispectral — which uses between 4-10 wavelengths of light sits between a standard digital camera and a hyperspectral camera.

LiDAR (light detection and ranging) — emits a pulse of light and assesses the amount of time it takes to return to the sensor. By using GPS to locate the sensor and the speed of light scientists can calculate the distance to the object and its height. This information is used to create 3D maps.

But the technology itself also poses significant challenges.

"The commercial success of drones is thanks to aerial photography and video — that's really where the commercial push is coming from. So the companies that produce drones don't produce them for scientists they produce them for the commercial market," he says.

"As a geographer I find myself being forced into this engineering field where I had to learn about sensor technology and I had to invest time in field trials where I had to go out and simply trial if it was going to fly.

"The sensor producers often sell very expensive sensors without turnkey software that can turn the raw data into useful products," he says.

Dr Joyce agrees.

"It's pretty easy if you want to buy a small system and you want to take aerial photos ... but what I want to do is use the cameras for making quantitative maps," she says.

"Getting to the point where we can extract [mapping] information in a fast and quantitative manner is still quite a way away."

"You have to think about matching the craft with the different cameras or sensors, work out how it's going to navigate and how you're going to get the data from it."

She likens the process of building a research drone to buying a car in pieces.

"It's like if you went into the dealership and they said, 'We'll give you the body from Toyota, I can give you the wheels, that's going to come from Ford, the steering wheel is going to come from somewhere else, if you want lights on that, we'll give you lights, but there's no cable so you're going to have build something yourself," she says.

"It is challenging. It's really exciting, but it's hard work too."