FIG Peer Review Journal


Spatial 3D Analysis of Built-up Areas (5487)

Oren Gal and Yerach Doytsher (Israel)
Prof. Yerach Doytsher
Professor; Chair - FIG COM3; President - ALSI
Technion - Israel Institute of Israel
Mapping and Geo-Information Engineering
Technion City
Corresponding author Prof. Yerach Doytsher (email: doytsher[at], tel.: +972 4 8293183 / +972 54 4690110)

[ abstract ] [ paper ] [ handouts ]

Published on the web 2012-02-02
Received 2011-11-03 / Accepted 2012-02-02
This paper is one of selection of papers published for the FIG Working Week 2012 in Rome, Italy and has undergone the FIG Peer Review Process.

FIG Working Week 2012
ISBN 97887-90907-98-3 ISSN 2307-4086


In the last few years, the 3D GIS domain has developed rapidly, and has become increasingly accessible to different disciplines. 3D Spatial analysis of Built-up areas seems to be one of the most challenging topics in the communities currently dealing with spatial data. One of the most basic problems in spatial analysis is related to visibility computation in such an environment. Visibility calculation methods aim to identify the parts visible from a single point, or multiple points, of objects in the environment. The paper presents a unique solution to the 3D visibility problem in built-up areas. A 3D visibility algorithm based on an analytic solution for basic building structures is introduced. A building structure is presented as a continuous parameterization approximating of the building’s corners. The algorithm quickly generates the visible surfaces' boundary of a single building. Using simple geometric operations of projections and intersections between visible pyramid volumes, hidden surfaces between buildings are rapidly computed. The algorithm, demonstrated with a schematic structure of an urban built-up environment and compared to the Line of Sight (LOS) method, demonstrates the computation time efficiency. Whereas the common visibility methods (LOS approach) require scanning of all the object’s points, the presented solution, by applying the continuous parameterization approximating of the building’s corners, is successfully avoiding the need to handle each point separately. As a result, the performance of the presented solution is much better than the common methods and for the analyzed samples the improvement time ratio was about 500 times. The basic building structure can be modified to complex urban structures by merging together a number of basic structures. The main contribution of the presented method in this paper is that it does not require special hardware, and is suitable for on-line computations based on the algorithms' performances. The visibility solution is exact, defining a simple problem that can be a basic form of other complicated environments.
Keywords: Geoinformation/GI; 3D visibility; spatial analysis; efficient algorithms; spatial information management