Drone gives bird’s-eye view of wetlands
Wetlands cover approximately 14 per cent of the land area of Canada. In late May, Dr. Jon Pasher, and his team from the Landscape Science and Technology Division’s Geomatics Section, unhooked the six carbon-fibre propellers of their unmanned aerial vehicle (UAV) at a test site on the Bay of Quinte, near Belleville, Ontario. Their aim was to capture a bird’s-eye view of this particular wetland.
While Dr. Pasher uses earth observation (satellite imagery) to map and monitor wetlands, the UAV can provide more detail than satellite imagery on vegetation types and water levels in the wetlands. This detailed field data from the UAV can be used to train and validate coarser data from satellite imagery taken over the same location.
“The first major step is to be able to identify and properly map the boundaries and the actual type of wetlands (based on hydrology and vegetation) using imagery,” he said. “This is especially difficult given their dynamic nature seasonally, but also annually.”
In partnership with Natural Resources Canada’s Canadian Centre for Mapping and Earth Observation, along with the United States Fish and Wildlife Service, the Geomatics Section is researching methods to map and monitor Great Lakes coastal wetlands using multi-scale earth observation.
The UAV flies 100 metres high, well above the tree canopy. The camera mounted on a remote-controlled swivel takes images of incredible detail – the pixels are 2-3 centimetres. It can take photos of the same object from multiple angles and hundreds of viewpoints. These images can be used to build 3D models and provide elevation data within wetlands. The GPS built into the tablet and UAV antennae provides exact location.
The drone is piloted through a handheld tablet. The battery pack on the UAV weighs five pounds, allowing 20 minutes of flying time, before needing to be swapped out for a fresh one.
“We can collect a permanent record on the ground on a specific day. If you fly the same wetland area year after year, you are able to map the extent of a wetland, or the growth or deterioration of canopies,” said Dr. Pasher. “High resolution satellite imagery is very costly for a small area and if there is cloud cover, you’re not able to have usable data.
“Using a UAV, you get a rapid assessment of what is going on below the clouds, giving us a bird’s eye view.”
Pilot Tom Giles prepares a mission in the Bay of Quinte wetlands.
This colorful image is derived information from Radarsat 2 satellite over a large region of the Bay of Quinte, and has a lot coarser resolution than the UAV image.
In May, the team took this UAV image of an approximate 100m x 50m section of a wetland with a resolution of 2cm pixels.
Dr. Jon Pasher
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