From electronic navigational chart data to sea-bottom models: Kriging approaches for the Bay of Pozzuoli

Abstract

<p class="Abstract">Electronic Navigational Charts (ENCs), official databases created by a national hydrographic office and included in Electronic Chart Display and Information System (ECDIS), supply, among essential indications for safe navigation, data about sea-bottom morphology in terms of depth points and isolines. Those data are very useful to build bathymetric 3D models: applying interpolation methods, it is possible to produce a continuous representation of the seafloor for supporting studies concerning different aspects of a marine area, such as directions and intensity of currents, sensitivity of habitats and species, etc. Many interpolation methods are available in literature for bathymetric data modelling: among them kriging ones are extremely performing, but require deep analysis to define input parameters, i.e. semi-variogram models. This paper aims to analyze kriging approaches for depth data concerning the Bay of Pozzuoli. The attention is focused on the role of semi-variogram models for Ordinary and Universal kriging. Depth data included in two ENCs, namely IT400129 and IT400130, are processed using Geostatistical Analyst, an extension of ArcGIS 10.3.1 (ESRI). The results testify the relevance of the choice of the mathematical functions of the semi-variogram: Stable Model supplies, for this case study, the best performance in terms of depth accuracy for both Ordinary and Universal kriging.</p>

Using Electronic Navigational Chart for 3d Bathymetric Model of the Port of Naples

“…The maps used for navigation, namely nautical charts, present distinctive elements for the knowledge of the seabed such as contour lines (called depth contours or isobaths) and selected depths (soundings) (Alcaras et al, 2021). As well known, a contour line is a curve that joins points of equal value; in cartography, contour lines join the points of equal elevation above a given standard reference surface like the mean sea level.…”

“…Electronic Charting Systems (ECS) and Electronic Chart Display and Information Systems (ECDIS) (Brčić et al, 2015). Nautical charts in vector format that comply with specific standards dictated by the International Hydrographic Organization (IHO), are called electronic navigation charts (ENCs) (Alcaras et al, 2021) and its use is mandatory for ECDIS. ENC is a major source of information for the navigator and for the safety of navigation, as it provides information on the depth of an area (Wlodarczyk-Sielicka and Stateczny, 2016).…”

Comparative Analysis of Selected Geostatistical Methods for Bottom Surface Modeling

“…It is regarded as an optimal method of spatial prediction that weighs the surrounding measured points to calculate a prediction for an unknown location [8,9]. It is widely used for digital spatial data modeling, as well as bathymetrical data modeling in many variants, e.g., in [10,11].…”

“…Typically used metrics are root mean square error (RMSE) and MAE (mean absolute error) [18][19][20]26] or root mean square standardized error (RMSSE) [15,21]. Sometimes other statistics are used, such as minimum and maximum values [10,25] or standard deviation [19,21,25]. In some cases, authors provide their own proposals for the comparison metrics.…”

“…In [21], prediction standard error is used. In many cases [10,11,25], also cross-validation is used. In [27], the author provides a complex approach to accuracy, comparing first the technologies and then analyzing geostatistical errors.…”