Drone opportunities and challenges in forestry
By Denis Cormier
December 9, 2015 - The days of drones being thought of as tools just for the military are long gone. The technology has found its way into a variety of commercial applications and the forestry sector is right there with other industries ready to take full advantage of this new remote sensing platform.
By Denis Cormier
Drones available for the commercial market are a much smaller version than the military counterparts, usually weighing less than 35 kilograms and often much smaller. But how can such a small vehicle be useful for an industry that deploys its operations in large areas?
The use of remote sensing in forestry is not new. Imagery from aircrafts and satellites has been used for decades to generate forest inventory and build annual and long-term forest management plans. However, this type of application is fairly static with long revisit times between image captures. Efficient tools and methods for more frequent revisits on a smaller scale could be very useful for improving decision making of more dynamic and evolving events, which is often the case in active harvesting areas.
In the forestry sector, there are two types of drone technologies that are starting to be applied.
The higher-end technology is mainly used for mapping purposes. It offers much higher accuracy than low-end drones and can accurately control the image capture to produce a high-definition orthomosaic (geometrically-corrected aerial photo) of a flown area and very detailed 3D images based on dense point clouds.
Flight and image acquisition with high-end drones are controlled by an auto-pilot module that determines the flight plan and triggers the sensor based on user-defined flight altitude and image overlaps. The images can then be stitched together to create an orthomosaic and pixels can be matched from overlapping pictures to produce a 3D surface model of the area covered. Compared to Lidar products, the surface model offers texture but does not penetrate the canopy to also offer a terrain model. Orthomosaics are useful to track operation progress and measure surface area coverage. 3D point clouds and surface models, combined with Lidar terrain models, can be used to assess tree metrics. Another application for drone technologies is for inventory management in sawmills. Drones can be flown over a mill for the purpose of measuring the volume of the log decks and chip piles in the yard using 3D point clouds.
They can also be used in forestry for the purposes of firefighting and fire prevention. Infrared technology can be used for hot spot detection in mop-up operations after a wildfire or a slash burning operation.
One barrier to using higher-end drones is often the price point. High-end drones typically start at around $35,000 and can cost as much as $100,000. While a well-trained service provider can justify this for regular use, it is not something that could be considered just another tool in a forester’s toolbox. However, the low-end drones, typically ranging between $2,000 and $5,000, are booming and increasingly powerful. They offer the potential of filling a monitoring niche for the industry.
Currently, you cannot use a low-end drone for a lot of precision or mapping purposes, but live-video streaming offers the possibility of monitoring an operation. One company is currently using its drone for safety audits. The company employs hand fallers and wants to make sure they’re following proper safety procedures, so staff members use the drone to monitor the hand faller’s activities from a safe distance.
We are also testing the use of drone flyovers for assessing regeneration in mountain pine beetle killed stands. The flyovers will save the crews from having to walk through at least the obvious low- or well-regenerated sites.
Low-end drones are typically low-cost and easily available, but when it comes to higher-end drones, a forestry company may be better off hiring a third party to provide the services they require.
Just remember that if you’re flying a drone for commercial purposes you need to follow Transport Canada’s regulations on UAVs, which can be found at: www.tc.gc.ca/eng/civilaviation/standards/standards-4179.html.
Denis Cormier is the research manager for silvicultural operations and remote sensing at FPInnovations.