Basic Geodetics What Every GIS User Should Know

Experts in Geomatics, Surveying, Positioning, Geospatial Data, and Mapping Sciences Basic Geodetics What Every GIS User Should Know Michael Barnes Cain & Barnes LP michael.barnes@cain-barnes.com Steven Long Shell steve.long@shell.com May 9, 2013

Knowledge Data Zone of the Geodetic Quagmire Techniques Tools Source: Cain & Barnes LP 2

Knowledge Basic Geography College, University Industry Training Learning & Development Data Basic Geodetics Techniques Tools 3

The least you need to know for Geospatial Data Management Geodetic Awareness of 5 Facts: 1. Geodetic Datum 2. Map Projection 3. Vertical Reference 4. Reference Orientation 5. Unit of Measurement 4

Geodetic Reference Surfaces h H N Normal to Ellipsoid Normal to Geoid N=h-H Ellipsoid Geoid Terrain b a Geoid Equipotential surface which approximates to MSL Ellipsoid Surface where Computations are made 1/f = a/(a-b) Source: APSG 5

Examples of Geodetic Datums 6

How many geodetic datums? Review www.epsg-registry.org 7

Before GPS we had 150 years of geodetic surveying e.g. National Geodetic Survey of Nepal 1981-1983 8

Hierarchy of Mapping Ellipsoid λp Equator Yp Φp hp P Zp Xp Projected CRS is a derivative of the Datum (Geog CRS) Easting, Northing, Elevation (above MSL) stable Unstable w/o Datum Datum (ellipsoid & origin) is the Foundation X,Y,Z Cartesian and Lat, Long, Ht Source: APSG 9

What are the main map projections in use? Mercator Transverse Mercator Universal Transverse Mercator Lambert Conformal Conic Others less frequently: Stereographic, Oblique Stereographic, Oblique Mercator, et. al. 10

Vertical Reference: Height, elevation, vertical datum or what? Local Kelly-Bushing, ground level, sea level, and assorted other local references Geodetic Either directly or derived from Mean Sea Level at one or more points at some epoch examples: NGVD 29, NAVD 88, IGLD85, OSU91A, EGM96, EGM2008 Tidal Defined by direct observation of tidal variations over some period of time at a specific location (or locations) examples: MSL, LAT, MLLW, MLW, MHW, MHHW 11

Potential for confusion with Local Vertical Datum Source: UKOAA, now OGP 12

Reference Orientations (5 kinds of north) True North = Direction of the meridian through a point Magnetic North = Differs from True North by declination and varies with time Grid North = Differs from True North by convergence Gyro North = a measurement of True North by instrument Plant North = strictly a local non-georeferenced orientation 14

Units of Measurement (13 kinds of feet and 2 kinds of meters in use) Reference Units: Biggest E&P Problem US Survey Foot vs. International Foot 1 ftus = 1.000002 ft (Intl), but this is still important for UTM, generating 30-60 foot errors, depending on latitude Other Feet: Clarke s Foot, Sears 1922, 2 for Benoit (both 1895), Gold Coast Ft., 4 Indian Ft. (1865, 1937, 1962 & 1975) and 2 British Feet (1865 & 1935), 2 meters: International Meter and German Legal Meter Other linear units include Chains, Links, and Yards 15

If you remember nothing else.. Latitudes and Longitudes are not unique unless qualified with datum name Projection Coordinates are not unique unless qualified with Projection name, Zone and Datum Heights are not unique unless qualified with Surface Reference (Vertical Datum) Orientations are not unique unless qualified with Heading Reference Units are not unique unless qualified with Unit Reference 16

Corporate Geospatial Data Managed at global or business unit level Company Propriety data Lease boundaries and licensed areas Seismic Well data Topographic and bathymetry Site survey and environmental data Infrastructure (pipelines, platforms, cables..) Third party industry data Seismic Well database Geologic data High resolution satellite imagery Gravity and magnetics 18

Past, Present, and Future Geodetic Integrity of Geospatial Data requires Source: OGP GIGS 19

Fundamental Exploration Data Sets Seismic surveys Wells, surface and well bore locations Boundaries, lease and license areas 20

Source: OGP 21

Source: OGP 22

80% + of all GG&E data Easting and Northing, X and Y or Y and X? Units of Measure stated? e.g. US Survey Foot International Foot Meter, etc Mandatory Metadata 23

NAD83 Seismic Survey incorrectly mapped as NAD27 400 feet of error as a block shift 24

Commercial Well Location Data Source: APSG 25

Digital Land Grids (Cadastral) Source: APSG 26

Area Discrepancy due to Incorrect Grid 27

Example Unit with Discrepancies Measured 28

Various State & Vendor Database Well Locations 29

Source: Conner 30

Source: Conner 31

Reasons for Mislocation of Wells Accuracy and reliability of original measurement systems and cartographic layers Miscalculations and poor QC Error in transformation of Coordinate Reference Systems Transcription errors, data entered incorrectly Transposing legacy data via new technologies Inadequate documentation Lack of industry standards for surveying and mapping 32

Well Surface Locations are frequently wrong Source: EnSoCo 33

Innovations in data use still requires sound geodetic and mapping principles 35

This image cannot currently be displayed. Time Lapse Plant refurbishment Iraq 7 months of overlay data 36

Geo-Information Integration 2010 DEM 2006 photography 1964 Surficial Geology 1968 topo 2012 topo 2012 aerial 37

Seismic Project, Wyoming Twenty Four 2D Data Geodetic Parameters Options NAD27 NAD83 WGS84 NAD27 / BLM 12N (ftus) NAD27 / BLM 13N (ftus) NAD27 / UTM zone 12N NAD27 / UTM zone 13N NAD27 / Wyoming West NAD83 / BLM 12N (ftus) NAD83 / BLM 13N (ftus) NAD83 / UTM zone 12N NAD83 / UTM zone 13N NAD83 / Wyoming West NAD83 / Wyoming West (ftus) NAD83(HARN) / UTM zone 12N NAD83(HARN) / UTM zone 13N NAD83(HARN) / Wyoming West NAD83(HARN) / Wyoming West (ftus) NAD83(NSRS2007) / UTM zone 12N NAD83(NSRS2007) / UTM zone 13N NAD83(NSRS2007) / Wyoming West NAD83(NSRS2007) / Wyoming West (ftus) SPCS83 Wyoming West zone (meters) SPCS83 Wyoming West zone (US Survey feet) 38

CRS Metadata inadequate? What is mislocation risk? NAD27 NAD83 WGS84 NAD27 / BLM 12N (ftus) NAD27 / BLM 13N (ftus) NAD27 / UTM zone 12N NAD27 / UTM zone 13N NAD27 / Wyoming West NAD83 / BLM 12N (ftus) NAD83 / BLM 13N (ftus) NAD83 / UTM zone 12N NAD83 / UTM zone 13N NAD83 / Wyoming West NAD83 / Wyoming West (ftus) NAD83(HARN) / UTM zone 12N NAD83(HARN) / UTM zone 13N NAD83(HARN) / Wyoming West NAD83(HARN) / Wyoming West (ftus) NAD83(NSRS2007) / UTM zone 12N NAD83(NSRS2007) / UTM zone 13N NAD83(NSRS2007) / Wyoming West NAD83(NSRS2007) / Wyoming West (ftus) SPCS83 Wyoming West zone (meters) SPCS83 Wyoming West zone (US Survey feet) 39

Same X,Y numbers used with different map projections NAD27 / Wyoming West or NAD83 / Wyoming West (ftus) Project Working West Wyoming Data on Vacation Nebraska State Park 40

Geo-Information Integration? Project GIS had 168 spatial layer 41

3D printing direct from GIS data 42

OGP ESPG Area Polygons reducing risk in handling of geodetic data 2,900+ polygons available online Source: OGP www.epsg-registry.org 43

Example: Nigeria Onshore and EEZ Rectangular Bounding Box 11 geodetic datums 13 Projected CRS* 25 transformations Geographic Area Polygon 3 geodetic datums 9 Projected CRS* 13 transformations * = datum + map projection 44

Knowledge Basic Geography College, University Industry Training Learning & Development Data Acquisition & Sourcing Processing & Integration Integrity & Handling Data basing & Retrieval Basic Geodetics Techniques Tools GNSS (GPS) Positioning GIS Mapping Geoscience Software Engineering Software Source: Cain & Barnes LP 46

Source: Schostak 47

Geospatial Integrity Compliance Grade????

Data Acquisition & Sourcing Processing & Integration Integrity & Handling Data basing & Retrieval Basic Geodetics Techniques Standards & Practices Procedures & Workflows Quality Control Processes Continuous Improvement Tools GNSS (GPS) Positioning GIS Mapping Geoscience Software Engineering Software 54

Forensic Geodetics of Well Location (US GOM) Followed the data from G&G through Drilling Operations 486 documents with well location stated Location stated as X and Y Often stated as UTM 16N ftus (aka BLM) NAD 27 and NAD 83 both are relevant 40% had no datum stated Geoscience data handling in UTM 15 and 16 at various stages of process Positioning difference is. Cost of the well is 55

NAD27 / UTM 15N vs. NAD83 / UTM 15N Positioning difference is 656 feet Cost of Well US$ 85 million 56

Transforming Coordinate Reference Systems Concatenated data operations are not trivial Source: OGP EPSG Registry 57

Knowledge Basic Geography College, University Industry Training Learning & Development Data Basic Geodetics Techniques Tools 58

Demographics of Participants 2007-12

Relevant and Useful?

Data Tools Zone of the Geodetics Quagmire Knowledge Techniques 62

Agenda Defining a GIS Project Working in ArcMap Dissemination of Geo-Information Summary

Overview GIS Project Setup What is my area of interest? How do I determine valid coordinate reference systems for my area of interest? What is the preferred coordinate reference system? Working in ArcMap What happens when I import my data into ArcMap? What is the preferred transformation? What is the maximum error if incorrect transformation is selected? Dissemination of Geo- Information Web Maps 3D Viewers Map Products Potential for geodetic integrity issues at all stages

Agenda Defining a GIS Project Working in ArcMap Dissemination of Geo-Information Summary

GIS Project Lifecycle Mandatory Coordinate Reference System (CRS) definition at project framing phase Coordinate Reference Systems (CRS) Ensure CRS validation for all subsurface applications Geomatics experts contacted at project start-up Source: McLay (2007) Users should not make assumptions regarding CRS!

Determining Coordinate Reference System OGP EPSG Area Polygons Reduces risk in handling of geodetic data 2900+ polygons available online Source: OGP http://info.ogp.org.uk/geodesy

OGP EPSG Area Polygons Download shapefile and load directly into ArcMap Area of Interest

EPSG Geodetic Parameter Registry Structured dataset of Coordinate Reference Systems and Coordinate Transformations Options to query by filter or retrieve by code Source: OGP www.epsg-registry.org

EPSG Geodetic Parameter Registry (con t) Source: OGP www.epsg-registry.org

Recommendations for CRS Selection Select an appropriate 2D geographic CRS ( datum ) which is in common use and has an accepted and well defined transformation to WGS 84 Use an appropriate map projection that is in common use and has small distortions Consider existing legacy data Consider export of produced data / maps (i.e., regulatory reporting requirements) Objective is to minimize geodetic risk Obvious choice is not always the best

Agenda Defining a GIS Project Working in ArcMap Dissemination of Geo-Information Summary

Geodetic Integrity and ArcGIS ArcMap has the ability to transform and re-project on the fly Can display data stored in one CRS as if it were in another, without altering the actual data Data frame s CRS is defined by the first layer added to the data frame or by manually setting the CRS through the data frame properties But there is no help to the user for the selection of the preferred transformation

Transformations When To Use A transformation is required when changing coordinates from one CRS to another CRS (i.e., NAD27 to WGS 84) Transform? No Transformation Required Source CRS: NAD27 Target CRS: NAD27 Transform? Transformation Required Source CRS: NAD27 Target CRS: WGS 84

Out-of-the-box ArcGIS Transformation No information about what are the differences between these transformations Which one is the preferred transformation?

Custom Transformations Users have the ability to create custom transformations Consult your local geodetic expert!

North American Preferred Transformations Transformations from NAD27 to NAD83 (WGS 84) NADCON - Alaska NTv2 NADCON - Conus

Difference Between NAD27 and NAD83 Source: Wikipedia http://en.wikipedia.org

Agenda Defining a GIS Project Working in ArcMap Dissemination of Geo-Information Summary

Web Maps Increasingly popular medium for displaying spatial information Uses internet browser Questions: 1) Do you know what coordinate reference system is being used by the application? 2) Do you know the coordinate reference system of your input dataset? 3) Do you know what transformation is being used between the application and the input datum? Source: ESRI http://www.arcgis.com/explorer Beware of your input data properties and data operations performed by application

3D Viewers ArcGIS Explorer and Google Earth Both allow input and display of GIS data How is this data handled? ArcGIS Explorer (Build 1750) Google Earth Pro (version 4.0.2737) Better integration with GIS data Uses WGS 84 as CRS Should only be used for small / medium scale mapping NADCON not supported Can consume shapefiles Uses WGS 84 as CRS Fitting of images of different types causes some of the images to be distorted. How much? Not advisable to do large scale digitization from images Need to transform input datum into WGS 84

Map Products All maps should have the coordinate reference system as the minimum; Name and EPSG code EPSG code is standard for oil and gas industry Example EPSG Name: NAD27 / BLM 15N (ftus) EPSG Code: 32065 ESRI names are not EPSG compliant Look up codes in EPSG Geodetic Parameter Registry http://www.epsg-registry.org/

Summary Don t make assumptions regarding coordinate reference systems Don t assume the software sorts out your geodetic problems Make use of OGP EPSG polygons and EPSG geodetic parameter registry Seek advice from geodetic experts when in doubt

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