Using the global positioning system to map disturbance patterns of forest harvesting machinery

Abstract

A method was presented to transform sampled machine positional data obtained from a global positioning system (GPS) receiver into a two-dimensional raster map of number of passes as a function of location. The effect of three sources of error in the transformation process were investigated: path sampling rate (receiver sampling frequency); output raster resolution; and GPS receiver errors. Total accuracy of traffic maps across a site (the summed areas receiving one, two, three, etc. passes) was not greatly affected by the error sources. The estimate of number of passes at a specific point, however, was heavily dependent on the presence of errors in the input data. Adding random offsets to each GPS position, for example, resulted in less than a 35% chance that an individual pixel would be classified correctly following transformation when compared with a reference raster. Although the absolute accuracy of the GPS–transformation system was not defined, it was concluded that data derived from applying it could be used to make estimates of total site disturbance and to identify regions of higher or lower disturbance but was less effective when applied in defining number of passes at a given point in a stand.