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1 INTRODUCTION
In the 1980s, computer software for geospatial data
(better known as GIS software) had been on the
market for more than a decade, but hardware,
especially “high‐resolution” graphic screens were
veryexpensiveandmostsoftwareveryspecialized.It
was still early days in the marine geospatial world,
and much would happen before geospatial data
wouldbecomemainstream.
Around the mid 1980s several national
hydrographicofficesacquiredgeospatialsoftwarefor
chart production and internationally there was talk
about geospatial standards. Under IHO was a
working group responsible for defining new feature
classesbasedondatafoundonnavigational
charts.In
1987wasthefirstworkreleasedas“DX‐87”(Digital
eXchange87).Itdidn’tgetmuchattentionaroundthe
world,butthedevelopmentwas(veryslowly)rolling.
Electronic navigational charts was coming, but
manywouldarguethatitwouldhavetakenforeverif
itwasn’tforonespecial“event”:
OnMarch24,1989,
theoiltankerExxonValdezranagroundontheBligh
Reef,PrinceWilliamSound,Alaska,USA,resultingin
anoilspillestimatedtohavebeenaround40,000tons
[4].Thereisprobablynotapersontodayinvolvedin
electronicchartsthathaven’theardthisstory.
Whether
(oil)accidentsactedasa catalystfor the
developmentofelectronicchartsandchartsystemsor
not is maybe less important! Many people in the
industry and government organizations agreed that
electronic charts and electronic navigational systems
were the future. In 1990 DX‐87 had become DX‐90
and included in
a new IHO standard named S‐57
‘IHO Transfer Standard for Digital Hydrographic
Data’.Atthistimesomearguedthatelectroniccharts
would replace paper navigational charts within 5
Towards a Universal Hydrographic Data Model
H.Astle&P.Schwarzberg
CARIS,Fredericton,NB,Canada&CARIS,Heeswijk,TheNetherlands
ABSTRACT: The International Hydrographic Organization’s (IHO) [1] Transfer Standard for Digital
HydrographicDataS‐57[2]standardhasbeeninforceformorethanadecade,andhassuccessfullybeenused
for official ENCs adopted by Hydrographic Offices around the world
and by navigation equipment
manufacturers.AdditionallyS‐57hasbeenusedformanyadditionalpurposes.HoweverS‐57,andespecially
theadministrationofthestandard,hasalsoexperiencedlimitations.In2010,IHOreleasedthenextgeneration
hydrographicstandard calledS‐100 Universal HydrographicData Model [3]. A movethat will open
up the
door to new possibilities to existing S‐57 users and potentially broaden the use of IHO standards in the
hydrographiccommunity.
ThispaperwilltrytoexplainwhyanS‐57replacementwasneededandgiveexamplesonsomepossibilities
withS‐100anditsderivedproductspecifications
suchasS‐101.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 7
Number 4
December 2013
DOI:10.12716/1001.07.04.12
568
years. More than 20 years later that has still not
happened,butit’scertainlycloserthanever.
2 S‐57TAKINGOFF
With the introduction of the IHO S‐57 standard in
1990 the world had probably received its first truly
international recognised data exchange standard.
Thereweretwomajor
purposeswiththestandard:
1 1Exchangeofdigital paperchartbetweennational
hydrographicoffices
2 2Exchange of electronic charts from national
hydrographic offices to mariners’ navigational
systemsonboardships.
Thefirstpurposenevertookoff.Themajorreason
for this is probably that paper charts are graphical
products and a geospatial standard focusing on
feature encoding of “real world features” like S‐57
did, was not suitable for this purpose. Converting
graphical datafrom allthe various systems used by
hydrographic office around the world is far more
complex than most people expected at that time. In
fact
paperchartstodaymostly,ifnotentirely,arestill
exchangedasrasterdataandnotasvectororfeature
data.
ThesecondpurposeusingS‐57forelectronicchart
exchangehadmore progress! Therewasmuch tobe
learnedandduringthefirstyearsaftertherelease,the
IHO DataBase
Working Group that maintained the
standard met multiple times per year, and the
standardwas constantly under revision. However in
themid1990sthestandardhadmatured,andby1996
edition 3.0 was released. It was decidedthis edition
would remain frozen for 4 years to ensure stability,
intended to help
hydrographic offices and, maybe
especially, navigational equipment manufactures to
finalize and release date plus equipment for the
market.
Only one year earlier, in 1995, had the
International Maritime Organization (IMO [5])
adopted the so‐called ECDIS Performance Standard
[6], meaning that Electronic Chart Display &
InformationSystems(ECDIS)nowwas
allowedtobe
usedfornavigation,insteadofpapercharts.Herealso
were many lessons to be learned, and amendments
were frequent in the early years. Work on this
standardhadtakenplaceinternationallyforaboutas
longasthedataexchangestandardandthetwohave
closeties.TheECDIS
standardrequiredthatchartsfor
ECDIS systems must be Electronic Navigational
Charts(ENCs)accordingtotheS‐57standard.
In 2000 edition 3.1 of the S‐57 standard was
released and this time the standard was frozen
“forever”. The production of ENCs still lacking
behindformany partsof the
world,and it wasalso
expensive for the ECDIS manufactures to keep
updating their systems. Freezing the standard was
intendedtohelpthat.Additionalitwasbelievedthat
onceanECDISwasdeliveredtoavesseltherewasno
guaranteethatsuchsystemwouldbeupdated,e.g.to
support new versions
of the standard. Neither the
ECDISstandard,northeENCstandard,hadmeansto
update ECDIS systems to accept new feature
classification or new symbology etc. This worked
relatively well for about half a decade, but by mid
2000s there were new requirements from IMO to
include new (environmental) features
on navigation
charts.InJanuary2007theso‐called‘Supplement1’to
S‐57 was released, and it was followed by another
supplementtwo years later.The evidencewas clear:
A frozen standard would not be able to support
futureneeds.
ItwasnotreallyaproblemwiththeS‐57
standard,
which originally included (technical) possibilities to
defineandencodenewfeaturetypes.Itevenincluded
away toencodeclass definitions ofnew features so
that navigational systems could “learn” about such
new features and present these features to the
mariner.Howeverthispartofthestandardwasnever
utilised.
Additionally S‐57 was intended to be used for
multiple product types, and had room for various
productdefinitionstobedefined. TheENCstandard
is actually “just” an appendix to the S‐57 standard.
Howeverthatpossibilitywasn’tused;partlybecause
ofthefrozenstateofthestandard.At
leastnotunder
IHOandofficiallynotpartofthestandard,butmore
about that below! The S‐57 standard and the ENC
productspecificationhadbecomealmostinseparable
andsomewhatsynonymous!
3 MULTIPLEPURPOSES
The frozen and somewhat limited S‐57 and ENC
specification did not stop other S‐
57 based
implementations.One of the earlier ideas for S‐57
wasforbathymetricsurveydataexchange,andeven
thoughthishasbeendonetosomedegree,therewas
much more use of the standard for other purposes.
Howevernoneofthesepurposesaredevelopedunder
IHO,butsomeofthem
startedusingS‐57asearlyas
themid1990s.
SomeoftheotherusesofS‐57are:
InlandENCs[7]
Electronic Charts for Inland ECDIS, which are
usedonrivers.
In 2001 the Economic Commission for Europe of
theUnitedNations(UNECE)adoptedtheInland
ECDIS
Standard as a recommendation for the
European inland waterway system; using Inland
Electronic Navigational Chart (IENC) data.
Outside Europe, other countries also looked at
Inland ECDIS and the U.S. Army Corps of
Engineers [8] developed the Inland Electronic
Navigation Charts. While the European Inland
ENCstandardextendedtheoriginalS‐57
standard
with new features, symbology and rules, the US
InlandENCstandardusedS‐57moreorlessasit
was. To align the standards the International
InlandENCHarmonizationGroup(IEHG)formed
in2003andthestandardsarenowmaintainedas
one standard. Other countries adopted this
standardand
InlandENCscoveringthousandsof
riverkilometresexiststoday.Countriesusingthis
standard include: Austria, Belgium, Brazil,
Bulgaria, China, Croatia, Czech Republic, France,
Germany, Hungary, Italy, Netherlands, Peru,
Poland, Russia, Serbia, Slovakia, Switzerland,
569
Ukraine, South Korea, USA, Venezuela (plus
others).
NotethatIENCsarenotoverlays;theywillnotbe
used at the same time as ENCs. They cover
different geographic areas and are made for
differentvessels.
IceENCs[9]
UsingS‐57 forencodingof Icefeatures started in
the
mid 1990s. These datasets are overlays with
additional dynamic (ice) information
supplementing ENC data.. Countries around the
North Pole, followed by countries around the
BalticSeaareamongtheplayers.
AdditionalMilitaryLayers(AMLs)[10]
Situation awareness layers of data supporting
military operations, which as the name indicates
are
overlay of additional data displayed on a
warship ECDIS (called WECDIS). Date layers
include bathymetric contours, routes, areas &
limitsfordangerandexerciseareas,fullwreckand
major bottom object information, detailed beach
andseabedenvironmentaldata,etc.
TherearemoretypeslikeBathymetricChartsand
specialised Pilot Charts. Many
more possibilities
using S‐57 for various purposes exist [11] and are
often generically referred to as Marine Information
Overlays(MIOs).Eachtypicallyhastheirownfeature
definitions,encodingrules,etc.Howeverthefactthat
theyareallbasedonS‐57makesitrelativelyeasyto
support more of
them. For instance a widely used
ENCproductiontool,CARISS‐57Composer[12],not
only allows users to create IHO ENCs but also the
otherS‐57producttypesmentionedabove.Userscan
evendefinetheirownS‐57producttypes.
4 WHAT’SNEXT?
ThereisnoquestionS‐57
willbeusedformanyyears
tocome.Thereissimplytoomuchdataandsomany
systemsusingS‐57preventingitfromdyinganytime
soon. ECDIS systems will be using S‐57 ENCs for
manyyearstocome.
Howeverthegeospatial world hasbeen evolving.In
the1980s
andeveninthe1990selectronicgeospatial
data was not mainstream, but today almost every
mobilephonehas not onlyelectronicmaps, butalso
navigation.ImaginingaworldwithoutGoogleMaps
in2013isveryhard!
The S‐57 standard was one of the first geospatial
standards, but it focused entirely
on marine
information,and(atleast)twoothermajorinitiatives
arenow moreknown thanS‐57 (atleast in the non‐
marinedomain):
GML[13]
Geography Markup Language (GML) is the
flavour of XML defined by the Open Geospatial
Consortium (OGC) to encode geospatial
information.Itisvery
generalandcanbeusedfor
manypurposes.Forinstancecandatatypesvarya
lot betweentwo different data sets both encoded
in GML.Meaning there is no guarantee that two
systemsbothsupportingGMLcanexchangedata.
Google’sKMLformatisoftencomparedto GML,
and can loosely be
described as a GML specific
flavour.
GML haswith the latestmajor version moved to
ISOconformity.
ISO/TC211[14]
The International Standards Organization’s
Standards Committee 2011 (ICO/TC 211) is
responsible for ISO’s standards on geospatial
information and many other organizations have
beenengagedinthisworktoo.OGC
andDGIWG
(Defence Geospatial Working Group) are among
these, and IHO have also been in close contact
with ISO in this area for decades. In 2012 a
Memorandum of Understanding (MoU) to
increasetheircooperationwassignedbyISOand
IHO.
ISO/TC211 hasreleased aset ofstandards know
as
the ISO 191xx series, each covering different
scopes.Forinstanceis19136thestandardforGML
and19115,whichmaybeisthebestknownofthese
standards,isthestandardformetadata.
5 NOTTHENEWS‐57
To resolve the issue described above (among other
things) IHO has developed
the S‐100 standard!
Howeverit willnot immediatelyreplace S‐57 and it
wouldbeamistaketocallitanewS‐57.
The work on S‐100 was started by the IHO
Transfer Standard and Maintenance Working Group
(TSMAD), which previously was known as the
DBWG,andthis
wasthegroupthatmaintainedtheS‐
57 standard. The initialversion of S‐100 was indeed
called S‐57 Edition 4.0! However since this new
versionshouldresolvesomeoftheissues/limitations
withS‐57(bothtechnicallyandadministrative)andit
isbasedonISO/TC211withnewterms
andmodelsit
was decided to give it a new name. Hence S‐100
which is following IHO’s naming convention for its
standards.
With S‐100 product specifications are kept
completely separate, meaning that feature classes,
encoding, etc. are not a part of S‐100. S‐100 doesn’t
evendictatewhat
fileformattousefortheencoding.
In line with ISO/TC 211 is GML for instance not
mandatoryformat,butanoptiondependingonwhat
needs to be encoded. It will be the product
specifications, which are separately maintained
standards, named S‐101, S‐102, etc. that will contain
the
encodingandotherproductimplementationrules.
Productspecificationsaredevelopedunderasetof
rules defined by S‐100, saying for instance that a
productspecificationmustconsistof(thusdefine)the
followingparts:
productidentification
datacontentandstructure
coordinatereferencesystem
dataquality
data
capture
datamaintenance
portrayal
encoding
productdelivery
S‐100 introduces some new data types and
structures for modeling and disseminating the data.
570
One of the new abilities in S‐100 is the ability to
handlemorecomplexattributesituations.Afeature
can now have multiple values of a given attribute
typeand ahierarchy ofattributeinformation canbe
modeled. Also a new concept called Information
Types allow common information to be
shared or
referenced by multiple objects.As part of the
development of S‐101 a richer encoding of the real
world should become available that will enable
systems and users to make better use of the
information.Thehopeisthatthiswillberealizedby
the end user systems
in order to provide improved
decisionsupportmechanisms.
Figure1. S‐101 example of complex attribute encoding in
one feature something that in S‐57 requires multiple
features.
Figure2.IHOGeospatialInformationRegister
A major component under S‐100 is the IHO
Geospatial Information Register [15] where feature
catalogues, defining the features to be used in the
product specifications, are registered. By registering
the feature catalogues (and the features defined in
these) in the IHO register it is hoped that feature
classes will
be shared (and possibly extended),
insteadof havingconflictingfeatureclasses between
product specification. It is also hoped that feature
classes can be shared between IHO standards and
otherstandards.TohelpensurethistheIHOregistry
is open to other non‐IHO standard for maintaining
their feature catalogues. Today both
IENC and Ice
IENCfeaturescanbefoundintheregistrytoo.
6 THEFRUITSOFS‐100
The first number in the new line of product
specifications defined by the IHO is S‐101, which is
the“NextGenerationENCProductSpecification”.S‐
101isunderdevelopmentandthe
firstdraftversionis
plannedfor late 2013.ECDIS systemsutilising S‐101
ENCsareexpectedoperationalin2018aftershoreand
seatrials.HoweverevenatthattimewillS‐100/S‐101
not replace S‐57 ENCs, but supplement them. S‐57
ENCs are not expected to retire before sometime
between2020and2030.
Figure3. IHO TSMAD S‐101 Draft implementation plan
(January2013)
The nextIHO productspecification in the lineof
numbers is S‐102 [16], which is the Bathymetric
Surface Product Specification. This product
specification is actually already released (in April
2012).The data/coverage type is aquadrilateral grid
coverage together with attributes known as a
BathymetricAttributedGrid(BAG).S‐102
isintended
fornavigationalpurposesusingadigitalsignature,or
for non‐navigational purpose (without a digital
signature).
Figure4.NavigationalsurfacewithENCfeatures.
UsinggriddedbathymetryinBAGformathasfor
some time been considered; for instance with Port
ENCs as described in the 2009 TransNav paper
571
“Enhance Berth to Berth Navigation Requires High
QualityENCʹs–ThePortENC–aProposalforaNew
Port Related ENC Standard” [17] by D. Seefeldt,
former Head of the Geographic and Hydrographic
DepartmentatHamburgPortAuthority.
S‐102griddedbathymetryisalsoverysuitablefor
web
viewinganddownload,asearlywork withS‐102
has been shown by the Canadian Hydrographic
Service[18].
Besides S‐101 and S‐102 is IHO also working
towards other S‐1xx product specifications! Marine
Protected Areas is expected to become a new S‐100
product specification called named S‐
103 Geospatial
standard for Marine Protected Areas and there are
more being mentioned as possible new product
specificationse.g.:
Routes
Boundaries
Ice
Currentsandtides
Etc.
TheIMOSub‐CommitteeonSafetyofNavigation
(NAV) is looking at e‐Navigation as an important
topic for the
future of nautical navigation. The Sub‐
Committeeone‐NavigationagreedtouseS‐100asthe
baselineforcreatingaframeworkfordataaccessand
servicesunderthescopeofSOLAS(IMO’sSafetyOf
Life At Sea). Plus the International Association of
Marine Aids to Navigation and Lighthouse
Authorities
(IALA)Councilhasapprovedregistration
of IALA [19] at IHO as a Submitting Organization
under the IHO GI Registry and as a domain owner
(i.e.theIALAdomainswithintheRegistry).
7 FLEXIBILITY
As mentioned earlier, S‐57 was intended to be a
frameworkformultipleproductsbutIHOonlyended
up with one product spec. One of the unfortunate
results of this and the frozen specifications is that
some implementations were designed to be static.
When IHO needed to add some new objects to the
catalogue it became clear that this would mean
softwareandsystemupgradestomakeit
work.With
S‐100theintentionistopreventthissituation.
S‐100 is under a new maintenance regime that
should allow new editions to be created as needed.
The concept is that S‐100 product specifications
would be based on a particular edition of S‐100,
whichwouldmeanthat
newS‐100editionscouldbe
released,whileproductspecificationsbasedonearlier
editionsstillwouldbevalid.ThiswillallowS‐100to
be updated to support new product specifications
requiring new elements not present in the older
editionofS‐100.
A concept with S‐100 is that
the more
common/expected changes should be treated as just
data updates and not require physical changes
(software,hardware)totheendsystems.Tothisend
S‐100 is defining the means to manage Feature
CataloguesandPortrayalCataloguesasdatathatcan
bedistributedandupdated.Ifthereisaneed
toadd
a new object to the Feature Catalogue an update to
theFeatureCataloguewould be releasedalongwith
corresponding updates to the Portrayal Catalogue
andwhenthesystemencountersthenewobjectina
datasetor updateit wouldrecognize thenew object
andbeabletodisplay
it.
Only if a product specification needs to include
moresignificantchangessuchasfileencodingordata
structures,then abrand neweditionofthat product
specification would be required and only in such
cases would it be expected that systems would
require corresponding software updates in order to
support
thenewspecification.
8 CONCLUSION
The expectation is that S‐100 will provide solutions
needed by the growing market of Hydrographic
productsandwillallowfortheflexibilitytogrowas
new needs are identified. This will not happen
without significant effort and involvement by all
aspectsoftheHydrographic
community.Ithasbeen
evident with the developments of S‐100 so far that
input and involvement from producing agencies,
system manufacturers, governing bodies and end
users are necessary for success.Having been
involvedin S‐57 andrelated technologies, plusin S‐
100 since its inception, CARIS is excited about
the
possibilitiesthatS‐100canbringtotheworld.
REFERENCES
[1]www.iho.int
[2]http://www.iho.int/iho_pubs/IHO_Download.htm#S‐57
[3]http://www.iho.int/iho_pubs/standard/S‐100/S‐
100_Info.htm
[4]http://en.wikipedia.org/wiki/Exxon_Valdez
[5]http://www.imo.org
[6]http://www.imo.org/OurWork/Safety/Navigation/Pages/
Charts.aspx
[7]http://en.wikipedia.org/wiki/Inland_Electronic_Navigati
onal_Charts
[8]http://www.tec.army.mil/echarts/
[9]http://hgmio.org/information.html
[10]http://www.ukho.gov.uk/Defence/AML/Pages/Home.as
px
[11]http://www.hgmio.org/specifications.html
[12]http://www.caris.com/products/s57‐composer/
[13]http://www.opengeospatial.org/standards/gml
[14]http://www.isotc211.org/
[15]http://registry.iho.int/s100_gi_registry/home.php
[16]http://www.iho.int/iho_pubs/IHO_Download.htm#S‐
102
[17]http://www.transnav.eu/Article_Enhance_Berth_to_Ber
th_Navigation_Seefeldt,18,280.html
[18]http://www.caris.com/downloads/brochures/The‐New‐
IHO‐S‐102‐Standard.pdf
[19]http://www.iala‐aism.org
