Analysis of raster data integration possibilities in an inland mobile navigation system

Abstract

It is the vector data that plays a key role in the commonly used ship navigation systems that present spatial information. Professional ECDIS (Electronic Chart Display And Information System), or its equivalent InlandECDIS systems, use electronic navigational charts and ENC/InlandENC standards for presenting geographical data. They are both build entirely on vector databases. On the other hand, recreational users are accustomed to all sorts of geoportals or services representing spatial information as ortho or raster image. It seems, therefore, that in terms of use of modern mobile systems for inland recreational users, it is especially important to ensure the ability to integrate raster data on screen. Displaying an orthophotomap as a background and applying IENC vector layers above it while maintaining adequate transparency may result in a readable image containing multiple pieces of content for everyone, even an inexperienced user.
The most problematic issue in the process of raster data management is providing access to data, by ensuring proper transfer and ability to obtain it from various WMS or WCS services. An alternative approach is to obtain raster layers (mainly aerial photographs) from the geodetic resources and to store them directly in the memory of the device. In this case the term "management" means the acquisition, transformation, conversion, integration and preparation of data for its visualization according to the accepted model of cartography. The article presents results of research on the possibility of raster data integration in the mobile inland navigation system. The study has covered two separate approaches. In the first one, after a detailed analysis of architecture services, together with its available interfaces, it proposed an algorithm connecting and operating WMS raster layer in the form of two modes of application - the viewing mode and the navigation mode. The second approach focuses on analyzing the possibility to use own raster mapping sources and also managing and providing this data to systems users. The analysis covered different ways of storing maps: in their original size and resolution, after transformation as a series of tiles covering a defined area or as certain sections visualizing only areas of interest. Finally, a solution consisting of storing and sharing raster map images only for limited areas representing regions interesting or important from the users' perspective, which - for some reasons - are not sufficiently represented by vector data. The article presents the results of the analysis and details of the adopted solution.