Baldo Stančić

Testing the data quality of existing 3D model of the city of Zagreb

Many countries in the world have created virtual 3D models of their major cities. Existing 3D model of the City of Zagreb, capital of Croatia, was created in the period 2007- 2008 based on aerophotogrammetry. It is a vector model consists of Digital Building Model (DBM) and a Digital Terrain Model (DTM). DTM is represented as a triangulated irregular network (TIN). The data were obtained from the photogrammetric mapping of roofs and DTM, defining and measuring the planes of roofs, facades and the ground that together make a 3D city model. The level of details corresponds to LOD 2 according to CityGML standard. 3D city models have become nowadays an increasingly important source of spatial information in different domains. An accurate and well organised 3D model of a city is the principal tool not only for modern urban planning, but also for disaster management, asset management, environmental monitoring, tourism, etc. With the growing interest in 3D modelling, the need for high quality data has arisen. This paper gives the analysis of the data quality of existing 3D model of the City of Zagreb in accordance with the ISO 19157:2013 Geographic information - Data quality standard. Data quality is being analysed using the defined data quality elements: completeness, logical consistency, positional accuracy, temporal quality, thematic accuracy and usability. Since the original 3D model was created in an old Croatian Coordinate Reference System (CRS), data were also transformed in to the new CRS and stored in CityGML format.

Archival cadastral data modelled in an electronic environment

Cadastre is founded on some basic principles. One of them is the principle of sustainability which implies keeping all documentation about changes made in the data. As a result of that, a great amount of archival cadastral documentation is generated. Documentation was mainly created and stored in an analogue environment, where main media is paper. Archival cadastral documentation is very rich and is often a unique data source for different studies and researches. Any search of the data or query is rather difficult or even impossible task to perform, mainly because of the analogue environment in which the data is stored. The goal of this paper is to model the archival cadastral data in an electronic environment, in order to make it searchable and with a higher level of accessibility. A problem regarding the transition of archival cadastral data from analogue to electronic environment was researched. Guidelines for their modelling in an electronic environment were given and a system prototype was realized. Some examples of queries were made and possible applications of archival cadastral data were proposed.