Mission Impossible: Positions determined by basic mapping-grade and recreation-grade GNSS receivers cannot emulate the actual spatial pattern of trees

TaeYoon Lee, Pete Bettinger, Krista Merry, Volkan Bektas, Chris Cieszewski


Global navigation satellite systems (GNSS) can provide valuable spatial information for effectively mapping and navigating through forest conditions. The accuracy of GNSS receivers has been well-tested under many environmental conditions. Depending on the technology and conditions, different amounts of variation will occur in the determination of a horizontal position. However, studies involving the spatial pattern and distribution of tree locations observed by independent GNSS receivers generally have not considered the horizontal position error inherent in the spatial data. We conducted this study to investigate whether tree locations determined by GNSS receivers can adequately represent the real point pattern of trees in a forest. We tested three different GNSS receivers: one mapping-grade receiver and two recreation-grade receivers. We determined tree locations at cardinal points around the stems. We compared these observed tree locations to actual tree locations which were determined through precise field measurements. This study confirmed that the horizontal positional error of mapping grade receivers was significantly lower than those of recreation grade receivers, regardless of measurement method. However, the observed point pattern of trees from the GNSS observations by GNSS receivers failed to adequately represent the actual regular point pattern of the trees.


Global navigation satellite system; complete spatial randomness; regular pattern; clustered pattern; root mean squared error; GPS receivers

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