Methodology of evaluation and correction of geometric data topology in QGIS software

Abstract

Geographical Information Systems (GIS) has revolutionised the process of collecting and processing data, therefore, more and more data recorded in an analogue form are transformed into the digital format. However, the process of generating vector models poses a risk of appearing defects of different types. A methodology of correcting common geometric and topological errors that appear in the manual vectorization of a raster model was presented in the paper. The research material was the vector layer including the digitized version of several dozens of drawings of spatial development plans. The paper also presents a procedure for creating a vector model of spatial data with attention paid to potential sources of errors which could be incurred at the stage of its creation as well as indicates methods for their prevention. The tools and plug-ins for evaluation and revision of geometric and topological correctness of a vector model implemented in QGIS software were mainly used in the survey. Elaborated algorithms are aimed at acceleration of data processing to allow their usage during that process. Indeed, proper conducting of spatial analyses needs to administer a data set which is free of errors. Only then, is it possible to obtain proper results and draw appropriate conclusions.

Keywords

• geometric data
• topology
• vectorization
• QGIS