Combine Harvest Area Determination by Vector Processing of GPS Position Data

The measurement of actual harvested area per unit time is an important component in the creation of accuratecrop yield maps. For row crops, such as corn, these measurements can be made manually on most conventional yieldmonitors. However, in drilled or broadcast crops a more accurate and automated method is required. In this study, avector method was developed to determine actual combine harvest area at each time step of the harvest process from aglobal positioning system (GPS) trajectory. The algorithm was coded into a geographic information system (GIS), andmodifications were made to increase computational efficiency. The method was compared with a previously reportedraster method of harvest area determination on data collected during the 1997 drilled soybean harvest, using highaccuracy real time kinematic GPS data. The vector method improved harvest area estimates by an average of 11% overthe assumption of a constant, full swath width and provided a number of distinct advantages over the raster method.