2. Land-Sea Data Interoperability?
John Pepper
Director- OceanWise Ltd, UK

3. A Few Facts Land and sea survey data rarely match up
Lack of definitive coast lines
MHW, MLW, MSL, LAT, CD?
Different Coordinate Reference systems?
Vertical datum issues
Techniques for surveying low-water areas are limited
Symbology on charts not relevant for wider use of hydrographic data

4. Coordinate systems in UK
ETRS89 (European Terrestrial Reference System 1989) is UK national coordinate system for 3D GPS positioning
OSGB36 National Grid (Ordnance Survey Great Britain 1936) is UK national coordinate system for topographic mapping
ODN (Ordnance Datum Newlyn) is the national coordinate system for heights above mean sea level (orthometric heights).

5. Coordinate Reference Systems
What is a CRS?
A coordinate system which is referenced to the earth based on a datum.
OGP, 2007, Surveying and Positioning Guidance note 1

6. Vertical Datum

7. UK National Positioning Infrastructure
The National GPS Network - contains over 90 active GPS reference stations of the OS Net network and about 900 passive reference stations
National Grid Transformation OSTN02 - the definitive transformation between ETRS89 and OSGB36 National Grid
National Geoid Model OSGM02 - the national standard precise geoid model, converting precise ETRS89 ellipsoid heights to heights above mean sea level (MSL)

8. Research Initiatives
Coastal Zone Prototype Map: Ordnance Survey & UKHO funded (Langstone Harbour near Portsmouth): 1993
ICZMap Data Research Project; UK Treasury Invest-to-Save : Ordnance Survey, UKHO and British Geological Survey (Isle of Wight, Milford Haven and Edinburgh demo sites): 2003
Vertical Offshore Reference Frame: UKHO/UCL: ?
Bringing Land and Sea Together (BLAST); EU Interreg 4B Funded Project (North Sea Region) project: 2012
NOAA VDatum programme (converts elevation data between tidal, orthometric and ellipsoidal vertical datum in specific US coastal areas):

10. OceanWise Marine and Coastal Digital Mapping
Raster Charts Popular Hydrographic Office Chart series supplied as GeoTIFFs so no need for additional software
Marine Themes UK Hydrographic Office (and other) data engineered into logical layers for easy use in GIS
Marine Themes DEM 1 arc second gridded dataset created from de- conflicted surveys, backfilled with chart data (where necessary)

11. DEM Transformations
OceanWise Marine Themes DEM can be transformed both horizontally and vertically
Vertical transformation undertaken by OceanWise using VORF
For the UK, options are:
Mean Sea Level
Ordnance Datum Newlyn (limited to 10km offshore)
OceanWise recommends Mean Sea Level for any projects in the marine domain

12. Challenges to Interoperability - 2017
Cartography still remains a challenge for vector data outputs
What is the referenced Coast Line?
Establish a common shoreline (to MHW?) attribute it and derive the DEM?
EMODnet Phase 3 programme requires:
hi-res DEM including coastal data
Higher resolution outcome (at 6arc’)
Coastal shallow water data included for first time

13. Nautical Symbology Raster Charts uses standard nautical symbology
Admiralty Publication available from all good book sellers
Subject to copyright so no online catalogue available!
ENC’s has common feature portrayal

14. Maine Mapping Symbology
There is no convention for symbolising marine features that are understood by non-navigational users
OceanWise developed its own symbology in consultation with users in 2003
Land data has well developed common convention of symbology globally :
For example: depicting offshore wind turbines in terrestrial mapping data, chart data and marine mapping?

15. Legacy Issues – Data from Product
Chart Boundary
Anchoring Area - UKHO ENC
Individual charts contain inconsistent and discontinuous features
Many important features only exist in ‘paper’ form and appear in re- purposed products unless resolved carefully
Ultimate solution is to go back to source records and re-create

16. Linking Data to Legislation and Policy
Anchor Area:
An area in which vessels anchor or may anchor. (IHO Dictionary, S-32, 5th Edition, 130)
But how real is the constraint, can it be amended or restrictions and risk mitigated? How do I find out more and who do I contact? What am I missing?

17. Marine Themes Persistent Unique Identifiers
Marine Themes features include a Unique Geographical Identifier (GID)
GID is persistent between updates and new source editions
Source attribute contains identifiers to source datasets e.g. ENC FOID or concatenated FOIDs
GIDs ideal to link feature to other datasets or documents
E.g. Anchorage Area - Attributes include a Marine Themes Unique ID and ENC ID(s)

18. Marine Themes Attributes
ATTRIBUTE NAME
DESCRIPTION
ELEVATION
OBSTRUCTIONS
TRANSPORT
INDUSTRIAL
ADMINISTRATIVE
REGIONS
GEOLOGY
TIDES
ABBRIEVIATED ATTRIBUTE NAME (see note)
GID
Object Identifier Y
THEME
Theme Name
FEATURE_CODE
Feature Code
CODE
NAME
Name
Description
DESCRIPTN
CATEGORY
Category
SOURCE_DATE
Source date
SOURCE_DAT
SOURCE_INDICATION
Source indication
SOURCE_IND
INFORMATION
Information
INFORMATN
CONDITION
Condition
STATUS
Status
RESTRICTIONS
Restrictions
RESTRICTNS
NATIONALITY
Nationality
NATIONALTY
ACCURACY
Accuracy
MATERIAL
Material
WATER_LEVEL
Water level
WATER_LVL
HEIGHT
Height
DEPTH
Depth
DEPTH_MINIMUM
Depth Minimum
DEPTH_MIN
DEPTH_MAXIMUM
Depth Maximum
DEPTH_MAX
MARKER_LIGHT
Light
LIGHT
MARKER_TOPMARK
TopMark
TOPMARK
MARKER_DAYMARK
DayMark
DAYMARK
UPDATED
Date feature was last updated

19. Example

20. Marine Themes Screenshot

21. Where are we now?
Land-Sea interoperability is resolved in terms of provision of survey data for charting and land mapping purposes (by CRS)
Lack of a joined-up approach by authoritative data providers in terms of enabling truly interoperable land-sea mapping data and DEM
Lack of priority afforded to resolve remaining challenges across (national) borders for GIS users
OceanWise has developed acceptable cartographic harmonisation (inc: symbology)
raster only (vector marine data is digitised raster!)
ENC Web Map Service
Standards and Specifications to do it by (IHO S-1XX)?

22. ENC Web Map Service

23. Screenshot

24. Screenshot

25. Screenshot

26. Screenshot