Eero Hietanen
National Land Survey of Finland
SDI services expert who is working with information management solutions, data models and linked data in National Land Survey of Finland
Current topographic database of National Land Survey of Finland includes over 5 million building features. Data is produced mainly from aerial images using stereo mapping. However, the main administrators and the producers for the building data are the municipalities. New National Topographic Database (NTDB) project aims to reduce duplicated data production and aims to find solutions to aggregate the topographic data from separate data producer into a one national data platform.
The first implemented data theme of NTDB, Buildings and other constructions, includes basic register information and 2D or 3D geometries of buildings and construction objects. The data is collected straight from the municipalities and other data sources. Feature Manipulation Engine (FME) ETL tool is used to create the schema transformations. The input data schema is based on the contracts made with data providers and the quality of the data is ensured with implemented automatic data quality evaluation. Schema transformation service enables a simple entry to the NTDB for the data providers.
NTDB is based on EnterpriseDB PostgreSQL solution. A custom made Java application for the data management is implemented to enable the updates of the dataset. The full life cycles of the data objects are controlled and permanent URIs are given to the data objects. The life cycle of the object is based on the life cycle rules, which are defined for each spatial object type separately. Imported spatial objects are compared to existing ones by using the rules to find out the new inserts, updates and deleted objects. A few data producers also maintain 3D building city models in CityGML format. In the NTDB, 3D geometries are handled as complementary geometries which are attached to the corresponding 2D objects.
NTDB platform offers a harmonised national-wide buildings dataset. The changes of the data are provided from the event interface to enable incremental updates of derived datasets. In addition, all the history data is stored in and provided from NTDB. This kind of platform facilitates the implementation of high quality applications and services for design, analysis and mapping purposes. In the future, new themes e.g. roads and addresses are planned to be added to NTDB.
In the presentation, import process of buildings from municipalities to NTDB is demonstrated. The functional solutions of NTDB are introduced and the challenges of the designed processes are discussed.
