By Charlaine Vaseur
The area of agricultural fields within the European Union (EU) member states are crosschecked against claims by European farmers to ensure that they receive the right amount of subsidies. Farmers within the Netherlands can submit manual digitized and GNSS data of their parcel to the implementing body of the Land Parcel and Identification System (LPIS) (the Department of Regulations) but there are several factors that can cause uncertainty in determining the actual area size of their parcel. Within this research project we determined what effect the uncertainty caused by the shape of the object and the surroundings had on the area size of a parcel when manually digitizing or measuring with a GNSS device. This was done by means of a model based research in which temporal semivariogram models were constructed, and Monte Carlo simulations with these models were conducted on different parcel shapes to assess the error propagation in different scenarios. By means of a probability study the models’ representation of true errors was assessed. Measuring with a handheld GNSS device proved to result in the highest propagated error overall for all three parcel types, while curvilinear parcels were an issue when performing GNSS measurements, and long parcels affected the error more when manually digitizing.
Keywords: LPIS; uncertainty; temporal semivariogram; error propagation; manual digitizing; GNSS.