Automated Update of Road Databases Using Aerial Imagery and Road Construction Data

The update of geodata 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 Today, this work is carried out mostly manually by an operator, who compares possibly outdated vector data from databases with remotely sensed imagery and/or other current information. In this paper we present a system for automated update of road databases 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. In our context updating comprises road data verification and change acquisition. The main goal related to the verification 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 aim of the change acquisition is to provide the operator with information about possible new roads to be added to the database. For the verification 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 graphbased 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. 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 information on the road geometry and its attributes. The change acquisition is supported by the analysis of road construction data. Planned road objects are used to define the search space in the image. The applied strategy is similar to the preceding verification of existing road data. Results of tests show the applicability of the proposed method for the update of topographic road databases.