Diploma Thesis by Beate Stollberg

Major Subject: Geoinformatics
Title: Geoprocessing in Spatial Data Infrastructures -
  Design and Implementation of a Service for Aggregating Spatial Data
Supervisor: Prof. Dr. phil. Alexander Zipf
Partner: Joint Research Centre (JRC) -
  Institute for Environment and Sustainability (IES), Ispra, Italy
Term of edit: 15-02.2006 until 15-08-2006

 

 


Introduction

Today, Spatial Data Infrastructures (SDIs) are primarily used to share and access distributed spatial data. However, the usefulness of SDIs can be improved by developing web services that are also capable of processing the shared data in order to tailor the results to the needs of the user. In this context, the Open Geospatial Consortium (OGC) has established standards for processing spatial data by introducing a discussion paper on the topic of a Web Processing Service (WPS).

Objective 

The goal of this thesis was the design and implementation of an interoperable Web Processing Service for Aggregating Spatial Data. The basis was a concrete use case concerning the combination of forest fire records with administrative boundaries within the EU funded project “Open Architecture and Spatial Data Infrastructures for Risk Management” (ORCHESTRA).

Summary

The developed Aggregation Service combines fire ignition locations which are made available as point data and administrative units which are made available as polygon data. It calculates the number of fires in the administrative units and aggregates the related attribute values of the fire data. Two steps are necessary: Spatial Join (based on the relational algebra operation join and topological relationships) and Aggregation (based on relational algebra aggregate functions). These are provided by the two service processes “Join” and “Aggregate”.

The conceptual design was mapped to the OGC WPS specification (see figure below for the mapping of the Join Process) and for the prototypical implementation the open source 52°N WPS framework, the JAVA programming language and JUMP libraries were used.

The service provides three processes, is extensible, and can be connected with other services in a service chain.