Karel Jedlička

Geodata interoperability and harmonization in transport: a case study of open transport net

BackgroundIn Europe, a lot of data portals are emerging on the local, national or interregional levels. These portals have a common objective to share data and information to its citizens and businesses, and to make information more accessible. However, studies showed that people are still facing difficulties in finding and reusing public sector information. To facilitate data reuse, the information should be available in a machine-readable format and agreed metadata standard, so that interoperability and discoverability could be enhanced.MethodsThis article focuses on the interoperability and harmonization of spatial and non-spatial data in the transport field. Both the open data and geospatial world have stable standards (such as DCAT and INSPIRE), and the GeoDCAT-AP is the first attempt in combining the two worlds. Through a case study approach, this article aims to provide insights in the implementation of this new standard and other interoperability cases in transport, such as the Data Tank data management system and a harmonized model for road network data.ResultsThe results are presented through a case study approach that was executed in the Open Transport Net project, and in consultation of the standard bodies Open Geospatial Consortium, the World Wide Web Consortium, and the in-house research centre of the European Commission, the Joint Research Centre.ConclusionsThe results highlight that still a lot of work needs to be done to combine both worlds, and that certain advantages and drawbacks need to be taken into account when combining spatial and non-spatial data.

Linked Forests: Semantic similarity of geographical concepts “forest”

Abstract Linked Data represents the new trend in geoinformatics and geomatics. It produces a structure of objects (in a form of concepts or terms) interconnected by object relations expressing a type of semantic relationships of various concepts. The research published in this article studies, if objects connected by above mentioned relations are more similar than objects representing the same phenomenon, but standing alone. The phenomenon “forest” and relevant geographical concepts were chosen as the domain of the research. The concepts similarity (Tanimoto coefficient as a specification of Tversky index) was computed on the basis of explicit information provided by thesauri containing particular concepts. Overall in the seven thesauri (AGROVOC, EuroVoc, GEMET, LusTRE/EARTh, NAL, OECD and STW) there was tested if the “forest” concept interconnected by the relation skos:exactMatch are more similar than other, not interlinked concepts. The results of the research are important for the sharing and combining of geographical data, information and knowledge. The proposed methodology can be reused to a comparison of other geographical concepts.

Semiautomatic construction of isobase surfaces

This article describes a method for semiautomated construction of isobase surfaces in the environment of a Geomorphological Information System (GmIS). The motivation to automate the process is that the manual construction of isobase surfaces involves several decision procedures, and also a lot of manual vectorization which can be time-consuming if the area of interest is large.A (semi-)automated process of isobase surface construction could accelerate the process of morphostructural analysis. Therefore, the contribution focuses on design, development and testing of such a method. The developed tools were compared to an expert driven construction of isobase surfaces. The automatically constructed data layers were compared to the layers that were constructed manually in the southwest part of the study area (Turcianska kotlina basin (Western Carpathians) and surrounding area in Slovakia). Three different statistical methods were used (correlation, linear regression and DTM volume difference checking). All three methods proved very high similarity of automatically created isobase surfaces to expert driven isobase surfaces creation. The results show that the method of semiautomated creation can be used in morphostructure analysis and save the time needed for manual isobase surface creation.The methods technological background is based on the ESRI platform. The original desktop solution has been developed for use on a client/server architecture that is able to present the capabilities of GmIS to a wider geomorphological audience. Display Omitted The analysis of isobase surfaces extends possibilities of morphostructural research.A semi-automated method was developed to replace manual construction of isobase surfaces.The analysis runs in a server environment, everyone can try it in web browser using own data.A comparison with the manually constructed isobase surfaces successfully verified the algorithms results.

Design and Evaluation of WebGL-Based Heat Map Visualization for Big Point Data

Depicting a large number of points on a map may lead to overplotting and to a visual clutter. One of the widely accepted visualization methods that provides a good overview of a spatial distribution of a large number of points is a heat map. Interactions for efficient data exploration, such as zooming, filtering or parameters’ adjustments, are highly demanding on the heat map construction. This is true especially in the case of big data. In this paper, we focus on a novel approach of estimating the kernel density and heat map visualization by utilizing a graphical processing unit. We designed a web-based JavaScript library dedicated to heat map rendering and user interactions through WebGL. The designed library enables to render a heat map as an overlay over a background map provided by a third party API (e.g. Open Layers) in the scope of milliseconds, even for data size exceeding one million points. In order to validate our approach, we designed a demo application visualizing a car accident dataset in the Great Britain. The described solution proves fast rendering times (below 100 ms) even for dataset up to 1.5 million points and outperforms mainstream systems such as the Google Maps API, Leaflet heat map plugin or ESRI’s ArcGIS online. Such performance enables interactive adjustments of the heat map parameters required by various domain experts. The described implementation is a part of the WebGLayer open source information visualization library.

3D Cartography as a Platform for Remindering Important Historical Events: The Example of the Terezín Memorial

Creation of 3D web maps is rapidly developing field with increasing importance and huge impact on 3D cartography. It is dealing not only with perceiving of space and space-relations of objects in 3D environment (apart from traditional 2D cartography), but thanks to the approachability of data via Internet, also with accessibility of those 3D web maps for the general public.

Centrality as a Method for the Evaluation of Semantic Resources for Disaster Risk Reduction

Clear and straightforward communication is a key aspect of all human activities related to crisis management. Since crisis management activities involve professionals from various disciplines using different terminology, clear and straightforward communication is difficult to achieve. Semantics as a broad science can help to overcome communication difficulties. This research focuses on the evaluation of available semantic resources including ontologies, thesauri, and controlled vocabularies for disaster risk reduction as part of crisis management. The main idea of the study is that the most appropriate source of broadly understandable terminology is such a semantic resource, which is accepted by—or at least connected to the majority of other resources. Important is not only the number of interconnected resources, but also the concrete position of the resource in the complex network of Linked Data resources. Although this is usually done by user experience, objective methods of resource semantic centrality can be applied. This can be described by centrality methods used mainly in graph theory. This article describes the calculation of four types of centrality methods (Outdegree, Indegree, Closeness, and Betweenness) applied to 160 geographic concepts published as Linked Data and related to disaster risk reduction. Centralities were calculated for graph structures containing particular semantic resources as nodes and identity links as edges. The results show that (with some discussed exceptions) the datasets with high values of centrality serve as important information resources, but they also include more concepts from preselected 160 geographic concepts. Therefore, they could be considered as the most suitable resources of terminology to make communication in the domain easier. The main research goal is to automate the semantic resources evaluation and to apply a well-known theoretical method (centrality) to the semantic issues of Linked Data. It is necessary to mention the limits of this study: the number of tested concepts and the fact that centralities represents just one view on evaluation of semantic resources.

Open transport map — Routable OpenStreetMap

This paper introduces Open Transport Map (OTM). The OTM is a web based map, depicting the road network of the Europe. The road network is derived from open source OpenStreetMap (OSM) but the data is stored in the Infrastructure for Spatial Information in the European Community (INSPIRE) Transport Network compatible data scheme. OTM is (contrariwise the OSM) topologically clean and routable data source, suitable for network analyses. A calculation of time and place related traffic volumes is one of analysis possible to perform on the base of such a data. The calculation of traffic volumes combines demographic data about the population and a road network vector data to create an enriched traffic model. This model can simulate traffic volume changes in the network through the time. The OTM is developed within the European projects OpenTransportNet, SDI4Apps and Foodie and it is freely available (under the ODbL license) for users further use.