Technical Release O6-R-23
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FOREST RESOURCES ASSOCIATION INC. TECHNICAL 600 JEFFERSON PLAZA, SUITE 350 RELEASE ROCKVILLE, MARYLAND 20852 PHONE: 301/838-9385 FAX: 301/838-9481 O6-R-23 GPS AND GIS COMBINE TO MAKE LAND MANAGEMENT USER-FRIENDLY Mapping: global positioning systems November 2006 www.forestresources.org/MEMBERS/serpub/06-R-23.html INTRODUCTION: Land managers have used aerial inspection and photographs for years to evaluate and classify forest lands under their care. Recently, Global Positioning System (GPS) technology has made navigating in the woods more accurate and precise. Ready available, affordable digital cameras now make taking hundreds of photos easy and cheap. GIS mapping technology and personal computers make mapping dynamic and detailed. Foresters in the Northeast have combined these useful technologies in a “user-friendly” way to get the most out of their time reviewing forests from the air, while using these systems to update forest typing and harvest records efficiently. GENERAL FEATURES: Annual flights by foresters over the lands in their care are a relatively inexpensive way to review thousands of acres quickly. Typically, a single-engine aircraft that can fly low and slow will be used. About 1,200 feet altitude seems to work best. For a two- to three-hour flight, the cost is usually Fig. 1: This computer screen view shows an area a few hundred dollars. Making notes on a map is with mapping and photo coverage. Arrow icons one way to record observations made from the mark the spot over the ground where a photo was taken, and in what direction it views. plane, but because of the large areas covered in one flight, it can been difficult to note everything seen during the short time foresters are in the air. Also, it can be difficult to communicate effectively what was seen to other managers or landowners’ representatives. Taking photographs from the plane—oblique aerial views—can help record the flight but, until the recent development of digital cameras, could be expensive and cumbersome. Also, the pictures taken often had little relevance later, unless prominent and easily identifiable ground features Fig. 2: This view shows the digital aerial photo taken like lakes or mountains were included in the from the GPS waypoint shown by the arrow icon. view. Consumer-quality digital cameras are now available that can take relatively high-resolution pictures (4 to 6 megapixels), and record up to several hundred of them on a single card or computer chip. GPS units are now commonly available that can accurately pinpoint any location on the ground to within the length of a pickup truck—and even greater resolution is available with the high-end units. Using these units while in the plane can then accurately fix the location of photographs taken while flying, if a waypoint is recorded at the same time the photo is taken. 06-R-23 - 2 - OPERATION: A recent review of a 23,000-acre ownership was required where harvesting activity had been on-going for several years, since the last formal aerial photographs and associated forest cover- typing had been completed. Because the new owner wanted to confirm harvest records, an aerial flight was planned to review and map this activity. A Cessna 172 aircraft was rented and two foresters accompanied the pilot. The forester in the front seat lined up the pilot with the boundaries of the parcel and then planned flight lines roughly a mile apart covering the entire property. The second forester had charge of a notebook and GPS unit. Once the plane reached the beginning of the flight line, the first forester would take an aerial photograph at an oblique angle from the window of the plane, looking down at roughly a 45-degree angle. At overlapping intervals, this forester would snap a photo and call out to the second forester in the back seat of the plane. The second forester would then mark a waypoint on the GPS and record the cardinal direction the photo had been taken toward—southwest, north, or whatever the direction was. They repeated this procedure until the property had been covered. Additional photographs were taken of areas of interest, with each snap of the shutter also given its own waypoint, recorded in the GPS unit. APPLICATION: Back at the foresters’ office, the GPS waypoints were downloaded to the computer and inserted into a Geographic Information System (GIS) map of the property. ESRI and MapInfo are examples of appropriate GIS software. Commonly available software such as MapTech’s Geopin function in Terrain Navigator Pro can be used for lands that have not been previously mapped. Using the waypoints that were now located on the computer map, a hyperlink was created linking the waypoint with its assigned aerial photograph, along with an arrow pointing in the direction the picture was taken. Using the computer mouse, the user then could click on the icon and that unique aerial photograph would pop up in the view. Using the photo-viewer software, the user could then zoom in or out on that particular view. This allowed the foresters quickly and accurately to view the photos taken over any particular area of the parcel and to discuss what was seen with others who had not accompanied them. While this method will not replace calibrated aerial photography and accurately typed maps, it does allow a quick and relatively inexpensive way to update harvest maps or evaluate lands for possible acquisition or management. CONCLUSION: Combining new consumer technology with a forester’s experience and knowledge can help communicate reviews of very large landscapes in a timely and cost-effective manner. Ted Shina, Senior Operations Forester Joel Philbrook, Operations Forester Lance Case, GIS/IT specialist Huber Resources Corporation P.O. Box 554 Old Town, Maine 04468 Reviewed by: [email protected] Joel Swanton [email protected] Northeast Region Manager [email protected] .