FIG GUIDE FIG PUBLICATION NO 62 Ellipsoidally Referenced Surveying for Hydrography INTERNATIONAL FEDERATION OF SURVEYORS (FIG) Ellipsoidally Referenced Surveying for Hydrography Jerry Mills David Dodd INTERNATIONAL FEDERATION OF SURVEYORS (FIG) Copyright © The International Federation of Surveyors (FIG), May 2014. All rights reserved. International Federation of Surveyors (FIG) Kalvebod Brygge 31–33 DK-1780 Copenhagen V DENMARK Tel. + 45 38 86 10 81 E-mail: [email protected] www.fig.net Published in English ISSN 1018-6530 (printed) ISSN 2311-8423 (pdf) ISBN 978-87-92853-09-7 (printed) ISBN 978-87-92853-16-5 (pdf) Published by International Federation of Surveyors (FIG) Cover images: David Dodd Layout: Lagarto Printer: 2014 Hakapaino, Helsinki, Finland CONTENTS LIST OF FIGURES ...................................................................................................................................vi ACRONYMS .............................................................................................................................................vii FOREWORD ...........................................................................................................................................viii PREFACE ....................................................................................................................................................ix 1 INTRODUCTION .............................................................................................................................1 2 VERTICAL POSITIONING ...........................................................................................................3 2.1 Vertical Components ...........................................................................................................3 2.2 GNSS Positioning ...................................................................................................................4 2.3 Effect of Pitch and Roll.........................................................................................................6 2.4 Heave .........................................................................................................................................8 2.5 Shipborne Derived Ellipsoid Depths ..............................................................................8 2.6 Airborne Lidar Derived Ellipsoid Depths ....................................................................10 2.7 Water Levels ..........................................................................................................................11 2.7.1 Traditional Tidal Datums and Tidal Zoning................................................11 2.7.2 Bottom Mounted Pressure Gauges ..............................................................12 2.7.3 GNSS Water Level Buoys ...................................................................................12 2.8 Vertical Datums ....................................................................................................................13 2.8.1 Geodetic Vertical Datum ..................................................................................14 2.8.2 Chart Datum (CD) ...............................................................................................14 2.8.3 Reference Ellipsoid .............................................................................................15 2.9 Ellipsoid to Chart Datum ..................................................................................................16 2.9.1 Topography of the Sea Surface......................................................................17 2.9.2 Hydrodynamic Models .....................................................................................18 2.10 Translation to Chart Datum .............................................................................................18 3 SEPARATION MODEL DEVELOPMENT ..............................................................................19 3.1 Simple Shift ...........................................................................................................................20 3.2 Interpolate Between Known SEP Locations ..............................................................20 3.3 Interpolate Between SEP Locations with a Geoid Model .....................................20 3.4 River SEP .................................................................................................................................22 3.5 Use of MSS, TSS and Hydrodynamic Models .............................................................22 3.6 Data Archive ..........................................................................................................................24 4 QUALITY ASSURANCE AND QUALITY CONTROL .......................................................25 4.1 Vertical Offset Calibration ................................................................................................25 4.2 Vertical Positioning Quality Control .............................................................................27 4.3 SEP Validation .......................................................................................................................28 5 VERTICAL POSITIONING UNCERTAINTY .........................................................................29 6 CASE STUDIES ...............................................................................................................................31 6.1 Swedish Maritime Administration ................................................................................31 6.2 CHS National Project: Continuous Vertical Datums for Canadian Waters (2013)..............................................................................................32 6.3 CHS Quebec Case Study (2009) .....................................................................................33 6.3.1 Data acquisition ..................................................................................................33 6.3.2 CARIS HIPS™ Data Processing .........................................................................34 6.3.3 Ellipsoid/Chart Datum Separation Models ................................................35 6.3.4 Channel Validation Model (SPINE) ................................................................35 6.4 CHS Central and Arctic ......................................................................................................36 6.4.1 Vertical Datums ...................................................................................................36 6.4.2 SEP Development Procedure .........................................................................37 6.5 NOAA VDatum ......................................................................................................................39 6.5.1 Transformations to NAD83 ..............................................................................40 6.5.2 Geoid Models of the NAD83 Ellipsoid to NAVD88 Separation ...........40 6.5.3 Topography of the Sea Surface......................................................................41 6.5.4 Tide Modeling to Compute Tidal Datums ..................................................41 6.6 NOAA Ellipsoidally Referenced Zoned Tides & GNSS Water Level Buoys ........42 6.7 United Kingdom Hydrographic Office VORF .............................................................44 6.8 North Sea Area Development.........................................................................................45 6.8.1 NSHC Tidal Working Group .............................................................................45 6.8.2 BLAST ......................................................................................................................45 6.8.3 Cooperation Between NSHC and BLAST ....................................................46 6.9 AusCoastVDT ........................................................................................................................46 6.10 US Naval Oceanographic Office (NAVOCEANO).......................................................46 6.10.1 NAVOCEANO with the Brazilian Directorate of Hydrography and Navigation (DNH) .......................................................................................46 6.10.2 NAVOCEANO Standard Operating Procedures ........................................49 7 CONCLUSIONS AND RECOMMENDATIONS ...................................................................56 REFERENCES ..........................................................................................................................................59 ABOUT THE AUTHORS ......................................................................................................................64 LIST OF FIGURES Figure 1: Vertical components. 4 Figure 2: Relationship between reference ellipsoid, antenna, water line (WL) and chart datum. 6 Figure 3: Effect of pitch and roll. 7 Figure 4: Effect of vessel pitch on height translation to the vessel reference point. 7 Figure 5: Heave interpolation of GNSS heights. 8 Figure 6: Ship borne observed vertical components. 9 Figure 7: Airborne observed vertical components. 10 Figure 8: OTG2 SEP determination from simultaneous WL observations. 12 Figure 9: Modified range ratio datum transfer relationship. 13 Figure 10: Chart datum, geoid, ellipsoid relationships. 16 Figure 11: Map of sea surface topography. [Taken from NASA, 2009.] 17 Figure 12: Local SEP interpolation using EGM08. [From Bill Elenbaas, 2012.] 21 Figure 13: Survey area and CD location for the lake