Implementation of the Buildings theme using data managed by ČÚZK in conformity with the INSPIRE data specification
The objective is to cover application schemas of the theme Buildings as completely as possible by data managed by Czech Office for Surveying, Mapping and Cadastre (ČÚZK) and to transform these data according to the INSPIRE data specification. Transformation process is set up, tested and executed on two levels and is documented to provide a guideline and best practice for reuse in the transformation of data for the theme Buildings, specifically for the application schemaBuildingsExtended2D.
The source is represented by two databases managed by the Czech Office for Surveying, Mapping and Cadastre (ČÚZK). Databases are Information System of the Cadastre of Real Estates (ISKN), containing buildings in the cadastral context, and Information System of Territorial Identification (ISÚI), containing buildings as construction objects. Both databases are based on Oracle database system, using Oracle Spatial for storing spatial data. Data from ISÚI are publicly available by law, as well as spatial data from ISKN. Databases do not have any metadata.
Target INSPIRE application schemas used
Application schemas BuildingExtended2D and BuildingsExtendedBase (XSD schemas were written by ourselves, according to the application schemas and available fromhttp://services.cuzk.cz/xsd/inspire/bu-ext/3.0/BuildingsExtendedBase.xsdand http://services.cuzk.cz/xsd/inspire/bu-ext2d/3.0/BuildingsExtended2D.xsd) were used, extending application schemas BuildingsBase and BuildingsCore2D.
The mapping from ČÚZK databases into the INSPIRE BuidlingsExtended2D application schema was based on the analysis of data in source databases.
In 2010 so called Publication database has been set up for publishing both INSPIRE and national network services. This database is on-line linked to the mentioned source databases ISKN and ISÚI and inside this database is the necessary conversion (using PL/SQL) into the INSPIRE data structure (including the Buildings theme) proceeded.
In the Publication database were created tables containing relevant data from source databases. Data were further displayed in database views in the structure conform to INSPIRE application schemas.
Special attention had to be paid to identifiers. Data came from two source databases, using different identification keys of objects.
Data Structures in source data were mapped on INSPIRE application schema structure. In some cases, one INSPIRE attribute could have be mapped to one of two or more attributes in source data. This was caused by the fact, that some buildings from two source databases overlapped.
Data in the same structure as in the database views respecting INSPIRE application schema structure were transformed into GML format. Transformation process itself was done using Marushka (3rd party software).
Transformation was tested on an integrated data sample. After testing, transformation process was executed on the whole data source. Part of the testing is also a validation. While the transformation is done, data are kept up-to date by syncing with the database.
The last step of sharing spatial data sets is creating metadata records for series of datasets and for both services. Series of datasets is a collection of all data sets for one INSPIRE theme. Metadata describes the data itself without taking its location into account.