How Do UAVs Work?
An additional input to our GIS solution is the use of Unmanned Aerial Vehicles (UAVs) to collect both high resolution imagery and create digital elevation models (DEMs). This imagery, with a pixel size as fine as 5 cm, provides the most clear, up-to-date visual survey of a site possible. The imagery can be used to better delineate site boundaries, view change to the site over time, or simply provide a highly intuitive backdrop to site drawings for easier visualization.
To complete a UAV study, a technician will first lay markers on the ground (bright plastic sheets) and collect additional data points using GPS equipment on the ground, giving an additional layer of information and accuracy. The resulting survey will have an accuracy of +-10cm.
The technician will then program an area and flight pattern into the UAV that will be used to capture the aerial survey. The UAV is launched and begins flying back and forth across the site, capturing hundreds of pictures, which can be used to form a mosaic of the site.
When the flight is complete, the technician lands the UAV using remote control, and connects it to a computer to download the data. This data is analyzed, formatted, and used to create maps of the site. With a high level of detail (pixel size as fine as 5cm, as mentioned before) the information that can be gained from these maps is immense.
Additionally, by incorporating high overlap between successive images, photogrammetric techniques can be used to obtain DEMs with 1m point spacing, providing a much higher level of detail than a traditional environmental survey. These elevation models can be used to estimate volumes in a landfill, highlight slopes exceeding a Certificate of Approval, or even calculate drainage patterns for larger sites. Incredibly, for most sites, a DEM can be completed in this manner in under an hour, with elevations captured for every metre or less across the site.