SPATIO-SEMANTIC COMPARISON OF LARGE 3D CITY MODELS IN CITYGML USING A GRAPH DATABASE
A city may have multiple CityGML documents recorded at different times or surveyed by different users. To analyse the city’s evolution over a given period of time, as well as to update or edit the city model without negating modifications made by other users, it is of utmost importance to first co...
Main Authors: | , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-10-01
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Series: | ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
Online Access: | https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/IV-4-W5/99/2017/isprs-annals-IV-4-W5-99-2017.pdf |
Summary: | A city may have multiple CityGML documents recorded at different times or surveyed by different users. To analyse the city’s evolution
over a given period of time, as well as to update or edit the city model without negating modifications made by other users, it is of utmost
importance to first compare, detect and locate spatio-semantic changes between CityGML datasets. This is however difficult due to the
fact that CityGML elements belong to a complex hierarchical structure containing multi-level deep associations, which can basically
be considered as a graph. Moreover, CityGML allows multiple syntactic ways to define an object leading to syntactic ambiguities in
the exchange format. Furthermore, CityGML is capable of including not only 3D urban objects’ graphical appearances but also their
semantic properties. Since to date, no known algorithm is capable of detecting spatio-semantic changes in CityGML documents, a
frequent approach is to replace the older models completely with the newer ones, which not only costs computational resources, but also
loses track of collaborative and chronological changes. Thus, this research proposes an approach capable of comparing two arbitrarily
large-sized CityGML documents on both semantic and geometric level. Detected deviations are then attached to their respective sources
and can easily be retrieved on demand. As a result, updating a 3D city model using this approach is much more efficient as only real
changes are committed. To achieve this, the research employs a graph database as the main data structure for storing and processing
CityGML datasets in three major steps: mapping, matching and updating. The mapping process transforms input CityGML documents
into respective graph representations. The matching process compares these graphs and attaches edit operations on the fly. Found changes
can then be executed using the Web Feature Service (WFS), the standard interface for updating geographical features across the web. |
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ISSN: | 2194-9042 2194-9050 |