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available to them was outdated and the resolution was too poor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: barmstro@co.otter-tail.mn.us or
218-998-8310.
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.