Consumer-grade global positioning systems performance in an urban forest setting

Abstract

Consumer-grade global positioning system (GPS) receivers are available for several hundred dollars or less and can be used for urban forestry measurement applications provided that acceptable accuracies are achieved. Potential applications include locating and mapping trees, arbor facilities, and urban infrastructure. We examined the measurement accuracy and reliability of six identical contemporary consumer-grade GPS receivers that collected data simultaneously at two distinct test courses. One test course was located in an open field and the other test course simulated an urban forest landscape with partial tree canopy cover and several buildings blocking a view of the horizon. We also varied data collection techniques by using 1, 10, and 30 point averages to examine the influence of different point averages on measurement accuracy and precision. Measurement accuracies for all GPS receivers averaged 1.8 m from true position at the open field course and 3.8 m from true position at the urban forest course with variations depending on when the courses were visited. We also found that although six identical receivers were used to collect measurements simultaneously and in close proximity to one another, there were statistically significant differences in the measurement accuracies of the receivers. However, no statistically significant influence of different point averaging (1, 10, and 30) on measurement accuracy was detected. © 2009 by the Society of American Foresters.