Web Map Service Architecture for Topographic Data in Finland
ISBN 978-85-88783-11-9
Authors
1Sipilä, T.
1NATIONAL LAND SURVEY OF FINLAND Email: teemu.sipila@maanmittauslaitos.fi
Abstract
Since 2012 National Land Survey of Finland has been renewing its web map services and digital map product pipelines based on Topographic database. A new service architecture utilizing Open Source software like PostGIS, GeoServer and MapCache has been developed. The core of the system is Visualization Service that provides up-to-date vector based styled map services. Visualization Service has replicated database system based on PostGIS software. Topographic data from production GIS environment is loaded and updated using custom data update process that use GML files extracted from the production environment as a data source. The main internal service layer of the new system is Web Map Service (WMS) providing dynamic map rendering services for other parts of the system. This implementation is based on a GeoServer cluster with each server having its own replicated PostGIS instance. Styled Layer Descriptor (SLD) files define shared portrayal rules for thematic, topographic and background maps. Performance for web map services is achieved by populating map tiles on Web Map Tile Service (WMTS) running MapCache software. Also raster map file products are generated by the system. These raster files in PNG format are delivered to customers via online file download service that provides Atom feed letting also customers to keep their file copies up-to-date. The most important benefit obtained from the new architecture is that same map layers and visualization definitions can be shared for all product pipelines. Also map products are now updated more frequently, performance of web map services has been enhanced and style descriptors are now more consistent. For WMTS services a national recommendation of tile matrix set to be used in Finland is successfully implemented by the new architecture.