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Cartographic abstraction and obfuscation techniques for 3D city models for privacy protection


Project duration: 11/2014 – 12/2017

Project funding: German Research Foundation (DFG)

As a result of the rapid ongoing developments in the field of sensor, analysis, and internet technologies, there is a continuous increase in the acquisition, presentation, and dissemination of geographical data. Especially for urban areas, there have been large-area photorealistic 3D city and street view models available on the internet, for quite some time. The technological trend is inevitably towards a greater amount of detail and higher (image) resolutions. There have also been initiatives to systematically capture indoor environments. Nevertheless, despite all technological possibilities, it is easily forgotten that the systematic data acquisition of our surroundings and the derived products can also be perceived as an intrusion into personal privacy. This holds true especially if the deployed sensor platforms allow for viewing perspectives that overcome natural visibility barriers, enabling views into private living spaces. Furthermore, national security agencies and government representatives consistently express concern regarding the presentation of security-relevant locations (government buildings, nuclear power plants, schools, churches, medical facilities, etc.) on the internet, which often results in the blurring or blacking out of relevant areas beyond recognition. These kinds of masking techniques, however, often make their visualization useless and lower the overall applicability of 3D city models.

In this research project, cartographic abstraction and obfuscation techniques are developed and applied in order to study and implement the protection of privacy and security-relevant areas with regard to the modelling, presentation and management of 3D city models. The objective is among others to translate the privacy measures known from the field of database management systems for handling personal data to the domain of 3D city models, without restricting their usage by the above mentioned filtering. Cartographic operations like simplification, aggregation, symbolization, typification etc. shall serve as elemental tools, which are (further) developed towards geometric and image based transformations of 3D building models if proven necessary. Besides the privacy requirements for affected individuals and facilities, the context, location, and authorization level of users, the semantics of buildings and regions, as well as temporal aspects shall be considered for the selection and configuration of abstraction and obfuscation levels. To dissolve the unavoidable occurring spatial privacy conflicts, geometric and image based conflict solving strategies as well as blending und rendering techniques are researched. The findings of the research project shall lead to the definition of abstract data types for spatial data bases and concepts for the integration of the developed abstraction and obfuscation techniques into the CityGML standard for 3D city models and into the OGC web services.

This project is supported by the German Research Foundation (DFG) [grant number KA 4027/1-1].

Contact:Prof. Dr.-Ing. Martin Kada,
Dr.-Ing. Yevgeniya Filippovska,
M.Sc. Izabela Karut


Filippovska, Y., Wichmann, A., Kada, M., 2016.
Space Partitioning for Privacy Enabled 3D City Models.
In: The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences (accepted).

Kada, M., Wichmann, A., Filippovska, Y., Hermes, T., 2016.
Animation Strategies for Smooth Transformations Between Discrete LODs of 3D Building Models.
In: ISPRS Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLI-B2: 413-420, DOI:10.5194/isprsarchives-XLI-B2-413-2016.

Kada, M., Wichmann, A., Hermes, T., 2015.
Smooth Transformations Between Generalized 3D Building Models for Visualization Purposes.
In: Cartography and Geographic Information Science, 42(4): 306-314, DOI:10.1080/15230406.2015.1039588.


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