Graph Supported Automated Verification of Road Databases Using Aerial Imagery

The verification of existing data is an important task in order to ensure a high level of data quality in Geographic Information Systems (GIS). Today this work is carried out mostly manually by an operator, who compares vector data from databases with remotely sensed imagery. In this paper we present a system for automated road data verification using digital image processing for the extraction of roads from aerial imagery and topological analysis in order to optimize the whole process in terms of reliability and efficiency. The main goal is to call the operator’s attention only to parts of the network where the automated process did not find evidence for a road. The road extraction is supported by the use of knowledge on the global level (whether the road is situated in rural, urban or forest areas), and the information on the road geometry and its attributes. The road extraction is executed twice: Firstly with a strict parameter control ensuring the minimization of false positives and a subsequent evaluation which denotes roads from the database being accepted or rejected. In a second step a graph-based search algorithm detects connections which are missing for an optimized road network. If rejected roads are part of these connections they are checked again using a more tolerant parameter control. Results of tests show the applicability of the proposed method for quality control of topographic road databases.