Lysandros Tsoulos

Interoperability and definition of a national standard for geospatial data: the case of the Hellenic Cadastre

Abstract This study, evaluation and proposal of a standard suitable for the exchange of geographic data was conducted by the National Technical University of Athens as part of a research project on behalf of KTIMATOLOGIO S.A. and the Hellenic Mapping and Cadastral Organization. The primary application interest was the Hellenic Cadastre Project, which can be seen as a case-study of the role of standards, the functionality they provide, and their effects. The study reported relates mainly to theoretical and scientific issues of standardization. Several subjects were addressed during the process of selecting the standard and a series of evaluation criteria were formed. Three primary trends in standardization were considered, Open GIS, ISO/TC 211 and CEN/TC 287, and a generic-profile-product approach was pursued. The selected standard was DIGEST-C with a customized (and not modified) implementation version of an Urban VMap product. The customization process included the association of the schema available in the selected standard with the schema that have been used so far in Greece for cadastre applications. The utilization and implementation of the selected standard, intended to be a National Spatial Data Exchange Standard, has various implications, which are reported and evaluated.

Choosing a Suitable Projection for Navigation in the Arctic

Navigation at sea is based on Electronic Chart Display and Information Systems (ECDIS) that allow for the use of a limited number of projections. As navigation in the Arctic region becomes a reality due to the progressive melting of the polar ice cap, a re-examination of the most suitable projections for navigation in the Arctic becomes timely. Several projections are proposed in the literature for this area. In our approach, the selection is based on an analytical study utilizing three criteria: the control of the magnitude of distortions within acceptable limits, the shape of great circles (GCs) and rhumb lines/loxodromes, and the shape of the graticule lines portrayed on the chart. The analysis carried out shows that to fulfill the set criteria, the arctic area should be divided into Arctic and sub-Arctic regions. More specifically, for the Arctic region the Azimuthal Polar Equidistant projection and the Azimuthal Polar Stereographic projection are the most suitable ones. For the sub-Arctic region, the Lambert Conformal Conic and the Conic Equidistant projection are considered more appropriate. All four projections proposed can be used for both the traditional nautical chart and the ECDIS, and both are considered as the starting point for further study of specific ECDIS requirements.

ICA contribution to the development of international standards of competence for nautical cartographers

Abstract. All professions face challenges as how best to ensure the achievement and continuance of the highest standards as they seek to determine and promulgate best practices. In the essentially linked professions of hydrographic surveying and nautical cartography these challenges become immediately international in their impacts and require close cooperation between the professional bodies representing surveyors, hydrographers and cartographers. The Standards of Competence for Nautical Cartographers are known in short form as S-8 and they describe the minimum required competencies for nautical cartographers. They indicate the minimum degree of knowledge and experience considered necessary for nautical cartographers and provide a set of programme outlines against which the FIG/IHO/ICA International Board on Standards of Competence for Hydrographic Surveyors and Nautical Cartographers may evaluate programmes submitted for recognition. The Standards recognize two levels of competence: Cate- gory A and Category B. In nautical charting communities, Category A programmes offer levels of comprehensive and broad-based knowledge in all aspects of the theory and practice of nautical cartography. Category B programmes provide a level of practical comprehension, along with the essential theoretical background, necessary for individuals to carry out the various nautical cartography tasks. The Standards have recently undergone complete review and should be ratified during 2017/18. This paper aims to bring the existence and aims of the Standards to the wider notice of ICA members and to describe the philosophy and aims of the review in meeting the professional competency needs of the nautical cartographic community.

Voronoi tessellation on the ellipsoidal earth for vector data

ABSTRACT Voronoi tessellation, and its dual the Delaunay triangulation, provide a cohesive framework for the study and interpretation of phenomena of geographical space in two and three dimensions. The planar and spherical solutions introduce errors in the positional accuracy of both Voronoi vertices and Voronoi edges due to errors in distance computations and the path connecting two locations with planar lines or great circle arcs instead of geodesics. For most geospatial applications the introduction of the above errors is insignificant or tolerable. However, for applications where the accuracy is of utmost importance, the ellipsoidal model of the Earth must be used. Characteristically, the introduction of any positional error in the delimitation of maritime zones and boundaries results in increased maritime space for one state at the expense of another. This is a situation that may, among others, have a serious impact on the financial activities and the relations of the states concerned. In the context of previous work on maritime delimitation we show that the Voronoi diagram constitutes the ideal solution for the development of an automated methodology addressing the problem in its entirety. Due to lack of a vector methodology for the generation of Voronoi diagram on the ellipsoid, the aforementioned solution was constrained by the accuracy of existing approaches. In order to fill this gap, in this paper we deal with the inherent attributes of the ellipsoidal model of the Earth, e.g. the fact that geodesics are open lines, and we elaborate on a methodology for the generation of the Voronoi diagram on the ellipsoid for a set of points in vector format. The resulting Voronoi diagram consists of vertices with positional accuracy that is only bounded by the user needs and edges that are comprised of geodesics densified with vertices equidistant to their generators. Finally, we present the implementation of the proposed algorithm in the Python programming language and the results of two case studies, one on the formation of closest service areas and one on maritime boundaries delimitation, with the positional accuracy set to 1 cm.

Toward the Development of a Marine Administration System Based on International Standards

The interests, responsibilities and opportunities of states to provide infrastructure and resource management are not limited to their land territory but extend to marine areas as well. So far, although the theoretical structure of a Marine Administration System (MAS) is based on the management needs of the various countries, the marine terms have not been clearly defined. In order to define an MAS that meets the spatial marine requirements, the specific characteristics of the marine environment have to be identified and integrated in a management system. Most publications that address the Marine Cadastre (MC) concept acknowledge the three-dimensional (3D) character of marine spaces and support the need for MC to function as a multipurpose instrument. The Land Administration Domain Model (LADM) conceptual standard ISO 19152 has been referenced in scholarly and professional works to have explicit relevance to 3D cadastres in exposed land and built environments. However, to date, very little has been done in any of those works to explicitly and comprehensively apply LADM to specific jurisdictional MAS or MC, although the standard purports to be applicable to those areas. Since so far the most comprehensive MC modeling approach is the S-121 Maritime Limits and Boundaries (MLB) Standard, which refers to LADM, this paper proposes several modifications including, among others, the introduction of class marine resources into the model, the integration of data on legal spaces and physical features through external classes, as well as the division of law and administrative sources. Within this context, this paper distinctly presents both appropriate modifications and applications of the IHO S-121 standard to the particular marine and maritime administrative needs of both Greece and the Republic of Trinidad and Tobago.

Towards New Standards of Competence for Hydrographers and Nautical Cartographers

Expectations and demands for education and training and the achievement and maintenance of core and new competencies in the hydrographic community are changing apace. The accepted international minimum competency standards for hydrographic surveyors and nautical cartographers have served the profession well, but are presently under review against these changed expectations. Community participation will be critical as the standards deal with and address the changes, ever mindful of the need for effective delivery of education and training across the wider profession