Admissible relative errors of the parcel area of a land parcel map base created as a synthesis of individual survey maps

Abstract

Today the land parcel map of Uruguay is available as an updated, integrated legacy digital cadastre which planimetric accuracy is not enough to assure geometric interoperability. The creation of a brand new land parcel map is being considered with a procedure yet to be defined but in any case subject to reasonable goals in terms of geometric accuracy. In this paper we have tested a direct procedure in which each parcel is joined to its immediate neighbors until a block is formed. In Uruguay such block will grow until a road, river or similar object is found. The block is manually inserted within the road network, which has absolute coordinates. The rural survey maps (approx. 250 000) are already scanned but they need to be vectorized and edited through scaling, rotation and manual matching to its neighbors. GNSS tracks for roads and highways are available for the whole country, so we could fit the block within them in order to properly register it. The resulting geometric accuracy was evaluated in terms of the relative error in area, which has a normal distribution with a mean 0.10% and a standard deviation 3.51%, leaving 82.0% of the parcels with relative area error less than 5%. The planimetric error, crucial to assure interoperability, was 53.79 m at the 95% confidence level.