Remote Controlled Aircraft Utilized to Collect Aerial Photography in Otter Tail County By Jane Mueller, Beltrami County GIS Director
Otter Tail County is on the cutting edge of technology when it comes to acquiring aerial photography. According to Brian Armstrong, the county's GIS Professional, the county is only the third entity in the United States to utilize a remote controlled aircraft known as a UAV (unmanned aerial vehicle) for the purpose of collecting aerial photography.
Brian stated that existing photography available to them was outdated and the resolution was too poor to build their complete inventory of county ditches. Potential and traditional solutions involved personnel walking or using an ATV with a GPS unit along the bank of each ditch in the county, which also meant acquiring permission from landowners to cross their property. Instead, the county purchased a remote-controlled UAV, equipped with autopilot, a GPS and a 10-megapixel digital camera. The unit can run on a Cartesian coordinate system or GPS. Flight paths are derived from existing photography and uploaded into the plane's autopilot system. The plane can also be controlled by the operator using a hand-held remote control unit should the need arise.
It took approximately seven months to get the necessary permission from the Federal Aviation Administration and the necessary insurance on the unit before it could make the first flight. In addition, county and city ordinances regarding the use of such aircraft also needed to be examined and followed. The UAV is capable of 40-plus mile flights; however, the plane needed to be in the line of sight at all times for insurance and FAA regulations, which meant keeping it within a distance of ½ - ¾ of a mile from an operator at all times. It was quickly discovered that operators could extend the overall range of the flight by following the plane with a car and keeping it within the restricted line of sight. Spotters were also utilized along the route to assist with this.
The plane can fly up to 3000-4000 feet above the ground but an altitude of 400-500 feet was used for this project. This resulted in a 3-4 inch pixel. Although the plane and technology works great for specific targeted areas of interest, it is not efficient for the capture of larger areas. There is considerable set up time needed to do a 160-acre tract with an actual flight time of approximately 20 minutes associated with area of that size. Weather conditions can also be restrictive as a wind of less than 20 knots (23 mph) and bright sun are needed for good quality photography.
The plane itself is fairly inexpensive ($300-$400) and measures approximately eight feet from wing tip to wing tip; however, the autopilot technology is expensive. Total costs of UAVs can run from $5000 - $50,000 depending on what additional technology is installed. Additional software is available that rectifies and date/time stamps images, allowing them to be downloaded in a GIS for digitizing and more. UAVs can also be equipped with live video back to the ground for additional capabilities. Additional uses for this technology within Otter Tail County have already included a search and rescue operation for the county's Law Enforcement Department.
For more information on the use of this technology, please contact Brian Armstrong at Otter Tail County: email@example.com or 218-998-8310.