End of this page section.

Begin of page section: Contents:


Object-based land cover classification of Graz (Austria) with special consideration of the third dimension

Project period: 2012-2019
Funding: Stadt Graz
Staff members: Wolfgang Sulzer (project management), Marc Muick, Ariane Droin, Christoph König

Project Description

The project deals with the creation of land cover classifications from very high-resolution, digital ULTRACAM aerial image data from 2007, 2011, 2015, 2018 and 2019 for the urban area of ​​Graz (Austria). The central part of the project work is the creation of the rule sets for the object-based classification and the handling of data-related problems such as the shadowed image areas in the image data. The legend and the land cover classes were developed in cooperation with the Department for Green Space and Waters of the City of Graz and the Department for Photogrammetry of the Graz Land Surveying Office. The aim here is to generate planning bases for urban planning and urban development and for the department for green spaces and water bodies of the Graz city administration. The regulations were developed and tested on the basis of test areas that represent the different urban structures. Furthermore, the classifications were carried out using elevation models (LiDAR and photogrammetry). The aim of this work step was to develop a set of rules that was as representative as possible for the entire city of Graz. In a further step, the generated sets of rules were implemented for the entire urban area of ​​Graz on the aerial photo data from 2007 and then evaluated. The possibility of height grading of the vegetation in general and in particular of the forest class investigated in this work enables a new way of looking at the forest areas of the city of Graz. Particularly due to the representation of approximate individual tree segments, this representation can be described as very realistic. In the context of this work, this subject area was also represented with separate single maps in order to increase the interpretability. In the last part of the work, the overall set of rules was applied to the aerial image data from 2011 to 2019. The different recording times (March, April, September and June) and the different geometric and radiometric resolution of the data resulted in new challenges for the classification. Finally, the overall project has to develop a generally valid evaluation methodology for future aerial survey projects of the city survey of Graz in order to keep the evaluation effort (adaptation of the regulations) as low as possible and to automate it.

Selected publications

  • Sulzer, W.,  M. Muick, W. Ganster, 2013: Objektorientierte Landbedeckungsklassifikation von Graz (Österreich) unter besonderer Berücksichtigung der dritten Dimension. In: Manfred SCHRENK, Vasily V. POPOVICH, Peter ZEILE, Pietro ELISEI (Ed.), 2013: Proceedings REAL CORP 2013, 651-660.
  • Muick, M., 2011: Objektorientierte Landbedeckungsklassifikation unter besonderer Berücksichtigung der dritten Dimension Am Beispiel dreier Testgebiete innerhalb der Stadt Graz. Unveröff. Masterarbeit am Institut für Geographie und Raumforschung,Universität Graz, Graz, p.86, 2011.
  • Sulzer, W., 2016: Reale Abbildung der Stadtentwicklung Graz – Landnutzungskartierung 1945 – 2015. Magistrat Graz, 260S.
  • Sulzer, W., 2018: Remote sensing based approach for monitoring urban growth in Graz / Austria. In: Grazer Schriften der Geographie und Raumforschung, Jg. (2018), H. 48: Spatial Tensions – Future Chances (2. Aufl.), 111-120.

End of this page section.

Begin of page section: Additional information:

End of this page section.