An Unmanned Aerial Vehicle for Rangeland Photography

Because of its perceived impracticality and expense, aerial photography from unmanned aerial vehicles (UAVs) remains virtually unused as a rangeland management tool. This underuse suggested 2 objectives. The first was to develop a UAV from off-the-shelf components that could acquire low-altitude large-scale photography for rangeland documentation. The second was to assess the UAV flight characteristics. A remotely controlled UAV suitable for 35-mm photography was built in 56 hours at a cost of 1 480. In a 2-year test period, the UAV successfully completed 100+ sorties at elevations ranging from 10 m to 1 000 m above ground. The average distance required for takeoff is 18.2 m whereas landing requires an average of 22.5 m. Average UAV airspeed at takeoff is about 11.4 m s-1. Typical cruise speed during photograph acquisition is 13.8 m s-1, resulting in 6.9 mm of blur from forward-image motion. The UAV is an inexpensive tool for monitoring rangeland condition from an aerial perspective. It is currently being used to map squarrose knapweed (Centaurea virgata Lam. ssp. squarrosa Gugl.) density at several rangeland sites in Utah.