2008 Volume 70 Issue 5 Pages 83-91
Micro-elevation maps were generated by mounting a single-carrier RTK-GPS receiver on a combine harvester, and were compared with others surveyed with a laser level. Under a favorable satellite arrangement (PDOP<2.0), minimum standard errors were 5.1mm in a concrete open space and 7.7mm in a paddy field after harvest. Periodical fluctuation was observed as PDOP increased, resulting in the maximum standard error of 16.9mm and 13.6mm, respectively (PDOP≈3.0). The moving average of the elevations taken more broadly across the paths of the vehicle lowered the standard errors by up to 47% in the open space and 34% in the paddy fields. However, loss of information of micro-topography of the fields should be taken into account in the paddy fields. The ratio of standard error to altitudinal variation was considered as a criterion, and the optimal area of the moving average was 6.0m×6.0m to minimize it. In the open space, renewing a reference elevation every 3 to 4 minutes compensated for the fluctuation and lowered the standard error by 17% while a high PDOP was observed.
