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1 INTRODUCTION
Collecting data for nautical charts is one of the basic
tasks of national hydrographic organizations (HOs).
Data are being collected by hydrographic survey that
is standardized in terms of methodology and
requirements for accuracy and reliability of collected
data. Standards are international and national.
International standards for hydrographic survey are
issued by IHO, while the national ones are issued by
HOs. National standards for the accuracy and
reliability of data should be equal to or rigorous than
international ones. The collection of data for the
production of nautical charts is possible only by
hydrographic survey, while their verification and
updating can be done by some auxiliary methods.
International and national standards of hydrographic
survey are necessary in order to achieve the
maximum possible uniformity in the production of
nautical charts used in international and national
navigation. Nowadays we can say that relatively good
results have been achieved at the level of
hydrographic survey standardization. Nevertheless, a
relatively large part of the world's sea is not
adequately surveyed in line with current standards.
Data on surveyed areas vary depending on the source
and range from 1 to 15% [11], while other depth data
on nautical charts were largely estimated. For this
reason, the data on depths shown on nautical charts
are not reliable enough in certain parts of the world
sea. An interesting fact is that the distance between
two adjacent depths on nautical charts is about 10
kilometers for more than half of the world's sea [21],
while more than 80% of the oceans floor is still not
mapped even at a resolution of 1km using the echo
sounding method [14]. Although HOs make great
Analysis of Crowdsourced Bathymetry Concept and It's
P
otential Implications on Safety of Navigation
I
. Pavić & J. Kasum
University of Split, Split, Croatia
J
. Mišković
Croatian Military Academy, Split, Croatia
D
. Alujević
Croatian Navy, Split, Croatia
ABSTRACT: Crowdsourced bathymetry (CSB) is relatively new concept of collecting bathymetric data. CSB can
be defined as the collection and sharing of depth data (and metadata) measured and collected by non-
traditional survey vessels equipped with navigation instruments, while maintaining their usual operations at
sea. International Hydrographic Organization (IHO) has developed Guidance on CSB. This document provides
framework for data collection, processing and information about data uncertainty. IHO has also developed
model within CSB concept in order to make standardization of CSB data. The data collected using CSB may
represent valuable supplement to the existing data collected by hydrographic survey. Despite this fact it is
necessary to emphasize that CSB data cannot be used as official data. CSB data collection has also potential
legal issues due to the character of sounding passage within territorial and internal waters of coastal states. This
paper emphasized the differences between hydrographic survey and CSB. Advantages and disadvantages are
analyzed with it's potential implication on safety of navigation. Due to the CSB data collection model
limitations, development of bathymetric data collection model on national level is recommended.
http://www.transnav.eu
the
International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 14
Num
ber 3
September 2020
DOI:
10.12716/1001.14.03.21
682
efforts in performing the hydrographic survey it will
take a long time for the survey to be done in
accordance with the applicable standards. Therefore,
the IHO pointed to the need to introduce a new
concept of bathymetric data collection, which is based
on the use of other data sources than official ones. At
the 5th Extraordinary Hydrographic Conference 2014,
the IHO established a Crowdsourced Bathymetry
Working Group (CSBWG) tasked with developing
guidelines for collecting bathymetric data from public
sources, ie, from ships using standard echo-sounders
for navigation and positioning systems. [11].
Companies that produce electronic chart systems (eg,
Olex, Navionics, Garmin, Lowrance, Survice, etc.),
companies that create their own databases (eg, Active
Captain) and other voluntary organizations (SeaID,
TeamSurv, OpenSeaMap) are also engaged in
collecting data from public sources.[4, 19]. These
companies and organizations have their own CSB-
related protocols. The collection of bathymetric data
by the CSB cannot replace the hydrographic survey,
but this concept is a complement to the hydrographic
survey. Its main advantage is the fact that collection of
bathymetric data can be done by using any type of
vessel. The fundamental disadvantage is the fact that
the CSB cannot replace the hydrographic survey. The
paper analyzes the role of IHO in the development of
the CSB concept, legal problems that arise due to the
collection of bathymetric data and the possibility of
applying this data in order to increase safety of
navigation at the global and national level with
special emphasis on the development of the national
CSB model.
2 IHO CSB CONCEPT DEVELOPMENT
The IHO has developed the CSB concept with the aim
of increasing the amount of seabed data collected, in
order to improve seabed mapping. Since the term CSB
derives from the term "crowdsourcing", it means that
it is addressed to a large number of persons, ie ships
that can collect bathymetric data. In this way, it is
possible to collect a relatively large number of
bathymetric data in a relatively short time, all at low
cost. These facts, together with the limitations of
hydrographic survey, led to the development of the
IHO CSB concept. The IHO CSBWG has developed
the publication Guidance on Crowdsourced
Bathymetry, which defines the concept, equipment,
methodology, format and uncertainty of data
collection, processing and storage. [8, 23]. It should be
noted that this publication provides a framework for
the CSB and it is neither authoritative nor binding,
but has the character of guidelines: The IHO CSB
concept is based on the Trusted Node model
(Figure1).
Source: Authors (in accordance with [8])
Figure 1. CSB data flow through Trusted Node model
According to the model, bathymetric data can be
collected by any type of ship (e.g., passenger, cargo,
public, fishing, pleasure boats, etc.). Data are collected
voluntarily during navigation, or during other regular
ship activities. In doing so, ships use navigation echo-
sounders (usually single beam SBES) for data
collection, while they use Global Navigation Satellite
System (GNSS) for positioning. The collected data are
submitted to the Trusted Node. Trusted Nodes are
organizations or individuals that serve as a liaison
between ships and the IHO Data Center for Digital
Bathymetry (IHO DCDB). In accordance with IHO B-
12 Trusted Node performs tasks and assist the
mariner by supplying data logging equipment,
providing technical support to vessels and
downloading data from data loggers [8]. The IHO
DCDB works with each individual Trusted Node to
standardize the data and metadata that will be
included in the database. The IHO DCDB assigns
unique keys for data authentication to each individual
Trusted Node. Authentication is performed to ensure
data integrity and an appropriate level of anonymity
of data sources [8]. Bathymetric data collected from
ships are provided to Trusted Node. The IHO
recommends that Trusted Node verify the data,
calculate uncertainty, and correct the data. After
verification and processing, the data is stored in the
IHO DCDB. This information is available to the public
online via interactive web map services for various
purposes related to seabed mapping [10]. Simply put,
the concept of IHO CSB means that data can be
collected by anyone and made available to anyone.
3 CSB DATA AVAILABILITY
The IHO established the DCDB in 1990 [9] as a global
database of bathymetric data for the development of
General Bathymetric Chart of the Oceans (GEBCO).
IHO DCDB is hosted by U.S. National Oceanic and
Atmospheric Administration (NOAA) National
Centers for Environmental Information [9, 17]. Data
are publicly available using the IHO DCDB Data
Viewer (Figure 2). The interactive menu map provides
access to data obtained using SBES, multibeam echo-
sounders (MBES), surveys conducted by NOAA, and
data obtained via CSB. Analysis of the IHO DCDB
interactive map shows that there is a relatively large
amount of data obtained from single beam and
multibeam surveys, while the amount of data