Renewal of the base model for geographic information of the Netherlands

In 2005 a base model for geographic information in the Netherlands was published named NEN 3610. The model consist of a modeling framework (based on the ISO19100 series) and a collection of extensible base classes. In the following years many organizations have built their models in conformance to this base model (IMRO, TOP10NL, IMTOP, IMWA, IMKICH, IMKL). The implementation of the base model strongly enhances the operational aspect of a successful National Geographic Register and related services. Moreover the base model approach has prepared the Netherlands for implementation of a similar approach followed in the INSPIRE initiative. Based on the experiences and national and international developments we are renewing the base model, this will be finished in 2009. In our paper we share our experiences with the base model of the last few years and give an overview of our proposed changes. The changes come from the following three main sources: NEN 3610 users were asked for change proposals, all current NEN 3610 models were analyzed for harmonization opportunities and finally the INSPIRE specifications that will probably influence many datasets under NEN 3610 were checked. Al these proposals were discussed in a NEN 3610 Framework group resulting in a new version of base model. The most notable changes with respect to the old version are: \u95 The introduction of design patterns as a way to harmonize data models. \u95 How to handle the fact that all organizations have a different way of looking at the world and hence splitting the same world into different classes. \u95 Integration of semantic decisions and implementation decisions in one model. As there are many similarities between the Dutch base model developments and the INSPIRE process we believe that conclusions from this project can be of benefit for the INSPIRE project and vice-versa.GIS TechnologyOTB Research Institut

Geo-informatie kent geen tijd?

Studiemiddag over temporele aspecten van geografische gegevens, georganiseerd door de Subcommissie Geo-Informatie Infrastructuur van de NCG en Geo-Informatie Nederland (GIN) op donderdag 17 september 2009 te Utrecht.OTB OnderzoekOTB Research Institute for the Built Environmen

Geo-DBMS als standaard bouwsteen voor Rijkswaterstaat

Oracle Spatial fungeert binnen Rijkswaterstaat als standaard bouwsteen voor ruimtelijke toepassingen. Doel van dit onderzoek is vast te stellen of andere DBMS'en op een zodanig niveau zijn dat deze ook als standaard bouwsteen zouden kunnen fungeren. De ontwikkeling van open source software biedt mogelijk een alternatief en kan wellicht tot interessante kostenbesparingen leiden. Het onderzoek betreft de vergelijking van Oracle Spatial met PostgreSQL /PostGIS, SQL Server en MySQL en heeft in drie fasen plaatsgevonden: fase 1 bestond uit een globale vergelijking van alle relevante DBMS'en (op basis van beschikbare openbare documentatie, waarbij MySQL is afgevallen vanwege te beperkte ruimtelijke functionaliteit); fase 2 bestond uit analyse van referenties en ervaringen van andere gebruikers (ook op niet technische aspecten, helaas konden in Nederland geen geschikte SQL Server referenties gevonden worden); fase 3 bestond uit het daadwerkelijk testen van de overgebleven DBMS'en (PostGIS en SQL Server, resultaten met Oracle vergeleken). De testen zijn uitgevoerd met een representatieve dataset: het Nationaal Wegen Bestand (NWB). De bijlagen bij dit rapport bevatten details met de systeemconfiguratie, de data, de selecties, de testresultaten en de reacties van de betrokken leveranciers/bouwers. Hoewel de verschillende databases ook op ruimtelijk vlak elk hun eigen sterke punten hebben kan worden gesteld dat naast Oracle, PostGIS het meest volwassen is en als standaard bouwsteen kan worden gezien.OTB ResearchOTB Research Institute for the Built Environmen

Archiving AIS messages in a Geo-DBMS

This paper reports on the result of two studies for using a geographical database management system for archiving Automated Identification System (AIS) message data. In this paper, we analyse the storage (using MongoDB and PostgreSQL) and we give a more in-depth description of a possible data model for archiving messages based on the bit vector type and functional indexes in PostgreSQL.OLD Department of GIS Technolog

A storage and transfer efficient data structure for variable scale vector data

This paper deals with efficient data management of variable scale vector data. Instead of pre-building a collection of data sets on different scales, we create an index structure on the base data set (largest scale data) that enables us to extract a map at exactly the right scale the moment we need it. We present both the classic version of the tGAP (topological Generalized Area Partitioning) data structure for storing our variable scale map, as well as an ameliorated version, both based on topological concepts. We prove that the classic structure needs in a worst case scenario O(e2) edges (with e the number of edges at largest scale). In practice we observed up to a factor 15 more edges in the variable scale data structure. The tGAP structure has been optimized to reduce geometric redundancy, but the explosion of additional edges is due to the changing topological references. Our main achievement finds its roots in the reduction of the number of edge rows to be stored for the ‘lean’ version (by removing the topological referential redundancy of the classic tGAP), which is beneficial both for storage and transfer. We show that storage space for the data set plus the index, is less than twice the size of the original data set. The ‘lean’ tGAP, as the classic tGAP, offers true variable scale access to the data and has also improved performance, mainly due to less data communication between server and client.GIS technologyOTB Research Institut