Table 2—Comparison of digital mapping products with Topo™.

DISCUSSION

Based on an admittedly small test, the GPS III Plus, with real-time DGPS, performed relatively well as compared to the survey-grade GPS. While obviously not as accurate, it did produce similar acreage estimates as compared to the compass and tape traverse. Figure 4 shows that the majority of the positions (13 of 20) were within a few meters of the positions logged by a cadastral survey-grade (sub-meter) GPS unit using DGPS. In the test against a known benchmark position, also performed well. Even without DGPS, relative accuracy appeared to be better than the 98.42 to 164.04 ft (30 to 50 m) expected.

The Topo!™ and MAPTECH® products produce excellent maps that compare favorably to simple mapping projects produced in ArcView®. Topo!™ does not have the acreage estimation feature that the MAPTECH® and the DeLorme map products possess. Two different software packages (CDs) must be purchased from Topo!™ to use GPS (GPS USA and regional coverage). The DeLorme Topo® software produced slightly less accurate mapping but had other features such as 3-D mapping that might be desirable in a variety of applications.

Figure 4—Comparison of GPS positions. (Stars are GPS III PLUS positions.)

RECOMMENDATIONS

Recreational GPS and mapping software have coevolved as new technologies. With the addition of real-time DGPS, GPS units provide natural resource managers a myriad of new applications as a low-cost alternative to more sophisticated GPS equipment and GIS. The GPS III Plus has proven to be a valuable tool for dispatching, reconnaissance, and mapping in wildland fire suppression. With the addition of DGPS, the GPS III Plus might also be used for low-precision closed traverses (similar to compass tape surveys with errors of closure of 1 in 100). The GPS III Plus, with DGPS, might also be used to traverse and document trail locations, locate and document element occurrences of rare plants, or mark cultural resources or other special locations. The GPS III Plus with any of the digital mapping products tested could be used in project layout work where a contour profile was needed (e.g., trail construction, timber sale layout for cable logging, temporary log roads, and skid trail location). Other possible applications include law enforcement investigation and evidence documentation, forest interpretive services, 3-D maps, and other customized maps for educational or public presentations. The use of these products allows managers a unique opportunity to introduce GPS and computer-generated digital mapping to a larger segment of the workforce that is currently not using either technology.