Improved Techniques for Depth Quality Information on Navigational Charts

TitleImproved Techniques for Depth Quality Information on Navigational Charts
Publication TypeConference Abstract
AuthorsKastrisios, C, Ware, C, Calder, BR, Butkiewicz, T, Alexander, L
Conference Name8th International Conference on Cartography and GIS
Conference DatesJune 15-20
Keywordsbathymetric data uncertainty, Electronic Navigational Charts ENC; uncertainty visualization; visual variables, geovisualization, spatial data visualization

Navigational charts contain a combination of geospatial information of varying quality collected at different times using various techniques. Depth information that was collected using hand deployed lead-lines may co-exist with more recent data acquired using single-beam echo-sounders, high resolution multi-beam echo sounders, and airborne lidar systems. The challenge for the professional mariner is to assess the quality of the depth information portrayed on the chart. Depth quality on charts is mainly encoded with one of the Category Zone of Confidence (CATZOC) values. CATZOC values provide information about the horizontal and vertical uncertainty of depth information, as well as the seabed coverage and feature detection. CATZOC is visualized in Electronic Chart Display and Information Systems (ECDIS) as an additional layer with symbols using a rating system of stars: six to two stars for the best to lowest quality data and “U” for unassessed data. The current visualization creates clutter which obscures the high quality depth information more so than the low quality information. Consequently, horizontal and vertical uncertainty may not be adequately assessed by the user. This work presents an intuitive method for portraying CATZOC, and for utilizing the quantified horizontal and vertical uncertainty in ECDIS. The proposed solution offers several improvements: it reduces ambiguity, it minimally obscures key navigational information, and it is effective in all ECDIS modes of operation.

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