S-57 CATZOC to S-101 QoBD: From Stars to an Intuitive Visualization with a Sequence of Textures

TitleS-57 CATZOC to S-101 QoBD: From Stars to an Intuitive Visualization with a Sequence of Textures
Publication TypeConference Abstract
AuthorsKastrisios, C, Ware, C
Conference Name2021 US Hydro Conference
Conference LocationOnline
Conference DatesSeptember 13-16
Keywordsbathymetric data portrayal, cartographic visualization, data quality, ecdis, ENC

The S-57 Category of Zone of Confidence (CATZOC) symbology with star glyphs has received much criticism for its effectiveness in maritime navigation. It adds significant clutter on Electronic Chart Displays and Information System (ECDIS) screens, obscures high-quality more than low-quality data, may not be visible in small areas, is not intuitive, and dominates the screen, especially in ECDIS dusk and night modes. Consequently, the International Hydrographic Organization relevant working groups have decided that the stars symbology will not be used in S-101 and alternative methods should be investigated. This work presents the development of new coding schemes for the visualization of the six categories of the Quality of Bathymetric Data, the successor of CATZOC in S-101. We propose the use of a sequence of textures created by combining two or more visual variables. The advantage is that textures are minimally used in ECDIS displays, and, when they consist of open meshes, they minimally interfere with other chart information. Each texture is visually denser than the last, with denser textures representing greater uncertainty. The textures contain countable elements designed so that the CATZOC in a region can be determined without recourse to a legend.  With the support of a user study, we demonstrate that this results in a visualization that is intuitive (thus making it easy to identify and memorize the different categories), does not obscure the underlying charted information (e.g., depths), does not alter user perception of it (e.g., shallow/ deep depth areas), and is effective in all ECDIS modes.