University of Twente Student Theses


Matching raster and trajectory data using web services

Shashish, Maharjan (2011) Matching raster and trajectory data using web services.

[img] PDF
Abstract:Moving objects are studied in different domains of science and technology. The movement of objects is influenced by various factors like environmental changes, influence of other agents, intrinsic properties, and spatial constraints. Researchers tend to explore relationship between moving objects and these influencing factors. They use conventional techniques to match trajectory data with external environmental data that affects objects’ movement. These methods consume time and resources. The development in web technology, new standards and protocols have added new scope in this process. This study focused on investigating tools and methods to match trajectory data with raster data using web services. Two different cases: iceberg movement and animal movement were studied. Iceberg movement can be affected by external environmental factors like sea surface temperature and ocean wind. Similarly change in vegetation can affect movement behavior of grazing animals. These environmental data are distributed in multidimensional grid format on the internet by different organizations using different standards. GISciecne community uses Open Geospatial Consortium (OGC) Web Coverage Service (WCS) for data access and Catalogue Service for Web (CSW) for searching metadata. Similarly, Earth Science (ES) community have developed set of protocols like Open-source Project for a Network Data Access Protocol (OPeNDAP) for data access and Thematic Realtime Environmental Distributed Data Services (THREDDS) catalogue for finding datasets. These standards can be utilized to find appropriate data sources, extract required subset of data. Later the trajectory data can be matched with extracted subset of data to find associated values. The client is required to access WCS and OPeNDAP servers. On the basis of the predefined criteria like version support, spatial and temporal subsetting, inteprolation support, suitable clients, OWSLib and Pydap were selected. The three tier architecture was chosen to develop a prototype web service. Users can interact with a client application to upload trajectory data, select suitable data sources and an appropriate interpolation method. The request sent by users was handled by python based middleware that was built on the top of the apache server. OWSLib and Pydap modules were used to connect and access data from the WCS server and OPeNDAP server respectively. After a subset of data was accessed from server, associated grid values were extracted and matched with trajectory data. For example iceberg trajectory data was matched with sea surface temperature and wind direction. In the case of missing values in the grid data, an interpolation method was applied. The final result was saved as CSV file format that can be later used for further analysis and visualization purpose. Also the performance of prototype was evaluated on the basis of time consumption for the processing. The web service was implemented as a proof of concept that will help researchers to explore possible relationship between change in environment and movement. Keywords data matching, trajectory, raster data, OGC WCS, OPeNDAP, web service
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Subject:38 earth sciences
Programme:Geoinformation Science and Earth Observation MSc (75014)
Link to this item:
Export this item as:BibTeX
HTML Citation
Reference Manager


Repository Staff Only: item control page