Lagring av 3D-geodata i databaser : en fallstudie i Malmö Stad

Sammanfattning: The interest in the production of 3D geo data has in recent years greatly increased, and many performers are interested in making use of 3D geo data for including urban design, planning, analysis, city models and web services. The use of 3D geo data can lead to an increased communication with the citizens thought interactive web maps. For example the user can slide around in a planned district or inspect how a project will affect the view from their balcony. Many municipalities can offer this type of data, but the process of retrieving, storing and the format for data exchange differ a lot between the stakeholders. This depends on the fact that there are no developed national or international standards for either the production process, storage or data exchange. This project is done in collaboration with Malmö Stad, which is one of the leading municipalities in Sweden when it comes to production of 3D geo data. They have a well-developed process for collection, production and data exchange of 3D geo data. They deliver primarily to analysis, 3D printing of physical models and web services. The 3D geo data are stored in file format that is resulting in an inefficient management and updating of the data as well as it requires a high standards of conflict and versioning. The purpose of this project is to investigate the possibilities and options for a storage structure based on a database that support 3D geo data. The investigation should include both database technology as well as different database solutions and eventually lead to implementation of a developed workflow for storage, managing and updating of 3D geo data. The case study is based on data from Malmö Stad and the choice of solutions and methods are partly based on their needs and possibilities. The project is made with a PostGIS database and the workflows for storing, managing and updating are developed with FME, an ETL-program for transforming and converting a large amount of geo data. A number of flows are developed: for storage, management and updating. The flow for updating the data is splitted into two scripts. The first script affects whether it is possible to update the 3D-database against the base map to find differences and locate which features that should be added or removed in the 3D database. The second script affects how the features can be updated and added in the database by using the program EspaCity, which is used in the current process in Malmö Stad. In addition to the mentioned flows, a script that test the ability to enable a delivery of CityGML format are developed. This was made because CityGML is an established format for data exchange in Europe. The results of the case study shows that a storage structure of this kind is possible for Malmö Stad and can be relatively easily integrated into the current process. In addition, the opportunity to update and adding features with EspaCity is a great asset. In the current situation, an update to the base map is not effective because the data for these are in different dimensions and the feature differ a lot because of the difference measure methods that are used for collecting the data. The results also shows that this type of solution, both the FME scripts and the general model should be possible to apply to other municipalities with only small adjustments for input and delivery data.