Volunteered Geographic Information (VGI) is a widely used data source in various fields and services, such as environmental monitoring, disaster and crisis management, SDI, and mapping. Quality is a critical factor for the usability of VGI. This study focuses on evaluating logical consistency based on the topological relationships between geographic features while considering semantics. It addresses internal (i.e., between thematic layers) and external (i.e., between specific features from different thematic layers) logical consistency. Attribute completeness is computed to support the use of semantics. A tool for assessing the consistency and attribute completeness is designed and implemented in the ArcGIS environment. An open-source web mapping application informs users about VGI consistency with multiscale visualization and indices. Data from OpenStreetMap (OSM), one of the most popular collaborative projects, are evaluated for six European cities: Athens, Berlin, Paris, Utrecht, Vienna, and Zurich. The case study uses OSM-derived data, downloaded from Geofabrik and organized into thematic layers. OSM’s consistency is evaluated and visualized at the regional, city, and feature levels. The results are discussed and conclusions on attribute completeness and consistency are derived.

Marine spatial “open” data infrastructures (MSDI) have a significant economic and societal potential for coastal nations and their realization is driven by the evolution of the International Hydrographic Organization’s (IHO) S-100 data model for facilitating marine domain interoperability and the World Wide Web Consortium’s (W3C) best practices for spatial data publishing on the Web. The recent European directive on open data and the re-use of public sector information, known as the “Open Data Directive” is a key driver towards the establishment of “open” MSDIs among other spatial data infrastructures. The paper discusses possible data architectures for the MSDIs, examines the maturity of open data platforms that they could be built upon and compares the most prominent marine spatial data models for their applicability in relation to three marine information domains. MSDIs can facilitate the continuous data capturing of spatial-temporal physical phenomena and human activities at sea and coastal areas, the corresponding data analysis and the decision-making for achieving continual improvement in the marine planning and management processes. MSDIs could play a key role in digital government transformation (DGT) for effective data sharing and offering marine services across various stakeholders. The information provided through a MSDI can be used for safe and efficient operation of maritime traffic, exploration and exploitation of marine resources, marine spatial planning (MSP), integrated coastal zone management (ICZM), environmental protection, and naval and maritime security.

This paper studies the design of point symbols on widely used online maps and apps that portray tourist points of interest (POIs). Tourist maps are among the most commonly used types of maps nowadays. The ease of travel leads to an ever-increasing demand for tourist maps. Therefore, appropriate map design, content and technical means are necessary for better information transfer and communication between the map and the user. Online maps and apps were selected according to specific criteria (e.g., language, geographic area, pictographic symbols, interactivity). Pictographic point symbols for POIs related to tourism activities were collected and described by variables. The frame and the pictogram of the point symbols were the two main directions for choosing the descriptive variables. Description is based on the cognitive scheme for interpretation of cartographic symbols with some improvements. The study reveals the characteristics of the point symbols and constitutes a documentation of the applied practices. The main trends prevalent in the design of these symbols are highlighted and commented on in relation to traditional cartographic practices and guidelines for the design of point symbols.

Electronic navigational charts (ENCs) are specialised geospatial datasets, issued by or on the authority of a government or hydrographic office, in accordance with the International Hydrographic Organisation's (IHO) standards, specifications and symbol sets. The datasets generally comprise encoded information collected from hydrographic surveys, aimed primarily at the safety of navigation. Most ENCs are not openly available, since the encrypted datasets can be acquired through various license schemes via a centralised distribution network coordinated by two organisations operating on behalf of the coastal states that produce them. This paper describes a methodology and an integrated system developed at the National Technical University of Athens Cartography Laboratory for the generation of web-based nautical charts utilising open data and free software. The system compiles nautical charts compliant with IHO's S-101 latest standard; using open hydrospatial data retrieved from marine spatial data infrastructures (MSDI) and other qualified volunteered geographic information (VGI) sources. Open-source geospatial libraries and web-map vector technologies are used to build the system components and software scripts developed to enable automated compilation. The study also discusses how the system can be improved further by leveraging web services for end-to-end process automation and satellite-derived bathymetry for accurate depiction of seabed topography in low-depth areas.

Visibility analyses provide an opportunity for addressing landscape exploration (e.g. assessing touristic experience). The locations of observers in 3D space and the topographic character of the overall landscape have been shown to act on the respective visibility spatial patterns (viewsheds). However, the way observers explore a landscape is not static but sequential. In this paper, we design explorative geographic visualizations (animated viewshed maps) which dynamically visualize the parts of a mountain landscape that are visible from hypothetical observers moving upon different topographic features (e.g. ridgelines). In these geovisualizations, the observers' elevation changes are displayed with inset profile graphs as well. Overall, these animated maps facilitate the visual exploration of viewsheds' evolution simultaneously with observers' changing positions. In this manner, insight is provided about the influence of the moving observers' topographic features and elevation upon the viewsheds' extent and configuration in a direct visual means. This qualitative approach is complemented by a statistical evaluation increasing the robustness of the results. It turns out that elevation per se is not such a crucial determinant for visibility, and topographic features should be encompassed in an attempt for further quantification and standardization of the way in which mountain landscapes are dynamically experienced.

A strategic instrument for the sustainable conservation of the fragile marine ecosystem is the designation of Marine Protected Areas (MPAs), within which various regulations exist for the protection of highly vulnerable species and habitats. These regulations can be depicted on Electronic Navigational Charts (ENCs) based on the new International Hydrographic Organization (IHO) S-100 series of standards, which support Marine Information Overlays (MIOs) that enrich the portrayed information by including both static and dynamic information, such as vessels traffic, tides, currents, and weather conditions, as well as essential information for the regulation of MPAs. Although, the new IHO S-122 Product Specification introduced specifically for the MPAs has been developed to encapsulate geospatial information for these regulations, the present edition does not specify portrayal. This paper reviews the legal foundation for the protection of marine mammals as well as the mapping methods used in selected study cases and builds upon these to present new, intuitive portrayal symbols for depicting the type of MPAs in combination with the regulations to be enforced on ENCs. Moreover, to support the global efforts for the protection of marine biodiversity, contemporary navigation systems aboard vessels can be used to enforce environmental regulations, and operations centers ashore can also monitor vessels’ passage and activities in MPAs. In that respect, this paper also discusses the concepts of Ecosystem Protection Zones and Environmental Risk Contours that can facilitate environmental risk-based voyage planning and preventive alarm services through Electronic Chart Display and Information Systems (ECDIS).