3,442 research outputs found

    Global-Scale Resource Survey and Performance Monitoring of Public OGC Web Map Services

    Full text link
    One of the most widely-implemented service standards provided by the Open Geospatial Consortium (OGC) to the user community is the Web Map Service (WMS). WMS is widely employed globally, but there is limited knowledge of the global distribution, adoption status or the service quality of these online WMS resources. To fill this void, we investigated global WMSs resources and performed distributed performance monitoring of these services. This paper explicates a distributed monitoring framework that was used to monitor 46,296 WMSs continuously for over one year and a crawling method to discover these WMSs. We analyzed server locations, provider types, themes, the spatiotemporal coverage of map layers and the service versions for 41,703 valid WMSs. Furthermore, we appraised the stability and performance of basic operations for 1210 selected WMSs (i.e., GetCapabilities and GetMap). We discuss the major reasons for request errors and performance issues, as well as the relationship between service response times and the spatiotemporal distribution of client monitoring sites. This paper will help service providers, end users and developers of standards to grasp the status of global WMS resources, as well as to understand the adoption status of OGC standards. The conclusions drawn in this paper can benefit geospatial resource discovery, service performance evaluation and guide service performance improvements.Comment: 24 pages; 15 figure

    Developing an open data portal for the ESA climate change initiative

    Get PDF
    We introduce the rationale for, and architecture of, the European Space Agency Climate Change Initiative (CCI) Open Data Portal (http://cci.esa.int/data/). The Open Data Portal hosts a set of richly diverse datasets – 13 “Essential Climate Variables” – from the CCI programme in a consistent and harmonised form and to provides a single point of access for the (>100 TB) data for broad dissemination to an international user community. These data have been produced by a range of different institutions and vary across both scientific and spatio-temporal characteristics. This heterogeneity of the data together with the range of services to be supported presented significant technical challenges. An iterative development methodology was key to tackling these challenges: the system developed exploits a workflow which takes data that conforms to the CCI data specification, ingests it into a managed archive and uses both manual and automatically generated metadata to support data discovery, browse, and delivery services. It utilises both Earth System Grid Federation (ESGF) data nodes and the Open Geospatial Consortium Catalogue Service for the Web (OGC-CSW) interface, serving data into both the ESGF and the Global Earth Observation System of Systems (GEOSS). A key part of the system is a new vocabulary server, populated with CCI specific terms and relationships which integrates OGC-CSW and ESGF search services together, developed as part of a dialogue between domain scientists and linked data specialists. These services have enabled the development of a unified user interface for graphical search and visualisation – the CCI Open Data Portal Web Presence

    An SDI for the GIS-education at the UGent Geography Department

    Get PDF
    The UGent Geography Department (GD) (ca. 200 students; 10 professors) has been teaching GIS since the mid 90’s. Ever since, GIS has evolved from Geographic Information Systems, to GIScience, to GIServices; implying that a GIS specialist nowadays has to deal with more than just desktop GIS. Knowledge about the interaction between different components of an SDI (spatial data, technologies, laws and policies, people and standards) is crucial for a graduated Master student. For its GIS education, the GD has until recently been using different sources of datasets, which were stored in a non-centralized system. In conformity with the INSPIRE Directive and the Flemish SDI Decree, the GD aims to set-up its own SDI using free and open source software components, to improve the management, user-friendliness, copyright protection and centralization of datasets and the knowledge of state of the art SDI structure and technology. The central part of the system is a PostGIS-database in which both staff and students can create and share information stored in a multitude of tables and schemas. A web-based application facilitates upper-level management of the database for administrators and staff members. Exercises in various courses not only focus on accessing and handling data from the SDI through common GIS-applications as QuantumGIS or GRASS, but also aim at familiarizing students with the set-up of widely used SDI-elements as WMS, WFS and WCS services. The (dis)advantages of the new SDI will be tested in a case study in which the workflow of a typical ‘GIS Applications’ exercise is elaborated. By solving a problem of optimal location, students interact in various ways with geographic data. A comparison is made between the situation before and after the implementation of the SDI

    The space physics environment data analysis system (SPEDAS)

    Get PDF
    With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (www.spedas.org), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have “crib-sheets,” user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer’s Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its “modes of use” with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.Published versio

    Recommendations for a polar Earth science portal in the context of Arctic Spatial Data Infrastructure

    Get PDF
    In recent years, the Arctic has been one of the most dynamic environments on Earth. As a result, scientific inquiry into the region has produced a large amount of data, with future projections of the volume of data for the Arctic as well as the Antarctic expected to increase by an order of magnitude. On the receiving end of these data, a challenge remains as how to best manage, archive and distribute the scientific observations so that they may be easily studied, analyzed and modeled. Aim The aim of this study is to analyze infrastructure studies and standards development efforts for the Arctic environment in order to recommend a way forward for polar science data dissemination. Methodology In this study, a discussion will be presented on the development of scientific data standards for the Arctic. The methods for implementing infrastructure in the Arctic will be considered in relation to current trends and best practices in data management and cyberinfrastructure. Relevant publications, feedback from researchers who use the data, and workshop documents resulting from discussions about science data management will be used as the information upon which to base these recommendations. The needs, goals and trends of the science community as a whole will be considered in order to propose a way forward. Results Developing a Spatial Data Infrastructure (SDI) specific to the Arctic will allow for seamless sharing of heterogeneous data. Also, this study found that the unique aspects of mapping at the polar regions point the way to implementing a method of science data dissemination via a scientific data portal specific to both the north and south polar regions.In recent years, the Arctic has been one of the most dynamic environments on Earth. Changes in the Arctic climate have been occurring at nearly twice the rate of the rest the world during the last 100 years (IPCC, 2007). This has resulted in increased scientific inquiry into the Arctic, and beyond to the Antarctic, as both polar regions pose similar questions for scientists. Satellites have been launched, airborne missions are under way, and field expeditions have been undertaken to collect scientific data that may be used to study these areas of recent change. On the receiving end of these data, a challenge remains as how to best manage, archive and distribute the scientific observations so that they may be easily studied, analyzed and modeled. Due to the importance of the location of the measurements of Earth science data, working from a shared representation of geographic features in these areas facilitates the use of the data across different platforms. Such shared standards can be defined as Spatial Data Infrastructure (SDI). SDI provides a base upon which the data can be structured to allow for widespread use and understanding of the information. In the Arctic, shared geographic data standards, or Arctic SDI, has yet to be defined. Because of the increase of scientific inquiry in this area, defining an Arctic SDI would be beneficial. Additionally, developing a centralized interface from which to distribute the scientific observations from these areas would facilitate the research efforts underway. Such a distribution center would likely take the form of a scientific data portal or Earth browser, which would utilize the standards identified by the SDI. This interface could service science data from the Arctic as well as science data from the Antarctic because of the unique methods for mapping at the poles. Shared development initiatives towards a data portal between the Arctic and Antarctic data management communities would result in more unified and succinct polar science. Thus, defining an Arctic SDI and sharing portal development initiatives with the Antarctic community would be of great benefit to those seeking a better understanding of the changing Arctic

    Geoportals: an internet marketing perspective

    Get PDF
    A geoportal is a web site that presents an entry point to geo-products (including geo-data) on the web. Despite their importance in (spatial) data infrastructures, literature suggest stagnating or even declining trends in visitor numbers. In this paper relevant ideas and techniques for improving performance are derived from internet marketing literature. We tested the extent to which these ideas are already applied in practice through a survey among 48 geoportals worldwide. Results show in many cases positive correlation with trends in visitor numbers. The ideas can be useful for geoportal managers developing their marketing strateg

    Managing big data experiments on smartphones

    Get PDF
    The explosive number of smartphones with ever growing sensing and computing capabilities have brought a paradigm shift to many traditional domains of the computing field. Re-programming smartphones and instrumenting them for application testing and data gathering at scale is currently a tedious and time-consuming process that poses significant logistical challenges. Next generation smartphone applications are expected to be much larger-scale and complex, demanding that these undergo evaluation and testing under different real-world datasets, devices and conditions. In this paper, we present an architecture for managing such large-scale data management experiments on real smartphones. We particularly present the building blocks of our architecture that encompassed smartphone sensor data collected by the crowd and organized in our big data repository. The given datasets can then be replayed on our testbed comprising of real and simulated smartphones accessible to developers through a web-based interface. We present the applicability of our architecture through a case study that involves the evaluation of individual components that are part of a complex indoor positioning system for smartphones, coined Anyplace, which we have developed over the years. The given study shows how our architecture allows us to derive novel insights into the performance of our algorithms and applications, by simplifying the management of large-scale data on smartphones

    Learning and Teaching with Geomedia

    Get PDF
    International audienceThis book presents a range of educational approaches and ideas around learning with and about geomedia, taking into account the potential as well as the risks and challenges associated with the use geomedia in education. This includes understanding the inherently biasednature of maps and other spatial representations; the power of geomedia produced by institutions, as well as the power of geomedia produced by lay persons; the use of geoinformation in the control and surveillance of individuals and groups, and the opportunities of georeferenced data to foster innovative knowledge. Addressing these aspects in essence means preparing students for an emerging Geoinformation society
    corecore