PPDM Data Management Symposium March 7, 2012 · PDF filePPDM Data Management Symposium March...

PPDM HOUSTON 2012

Experts in Geomatics, Surveying, Positioning,

Geospatial Data, and Mapping Sciences

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Michael Barnes APSG Foundation Chair 2010-2015

APSG Chair 2008-2009

PPDM Data Management Symposium March 7, 2012 Houston

PPDM HOUSTON 2012



Geodetic Integrity:

The Essential Basics for Data Managers and Users

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Michael Barnes Cain & Barnes LP

The Geomatic Experts Group

PPDM HOUSTON 2012

Data Tools

Knowledge Techniques

Zone of the Geodetic Quagmire

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PPDM HOUSTON 2012 4

Data Acquisition & Sourcing Processing & Integration Integrity & Handling Data basing & Retrieval

Tools GNSS (GPS) Positioning GIS Mapping Geoscience Software Engineering Software

Knowledge Basic Geography College, University Industry Training Learning & Development

Techniques Standards & Practices Procedures & Workflows Quality Control Processes Continuous Improvement

Geodetic Integrity

PPDM HOUSTON 2012


Tools

Knowledge

Techniques

Project Work

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PPDM HOUSTON 2012

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PPDM HOUSTON 2012 7 Source: OGP

PPDM HOUSTON 2012 8 Source: OGP

PPDM HOUSTON 2012 9

80% + of all GG&E data

Mandatory Metadata

Units of Measure stated ? e.g. US Survey Foot International Foot

Metre, etc

PPDM HOUSTON 2012

Commercial Well Location Data

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Source: APSG

PPDM HOUSTON 2012

Commercial Digital Land Grids

11 Source: APSG

PPDM HOUSTON 2012

Area Discrepancy due to Incorrect Grid

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PPDM HOUSTON 2012

Example Unit with Discrepancies Measured

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PPDM HOUSTON 2012

Various State & Vendor Database Well Locations

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PPDM HOUSTON 2012 15 Source: Conner

PPDM HOUSTON 2012 16 Source: Conner

PPDM HOUSTON 2012 17

Libya Well Location Database

Satellite Imaging Corporation


Potential Causes of Well Positioning Errors

Why are the wells plotted at incorrect locations in the

previous Libyan example?

• Possibly some have used the wrong geodetic datum • Or incorrect datum transformations to WGS 84 were

used • Perhaps some were plotted from “pre-plot” locations • Different positioning technologies over many years

• The mis-positioning here is probably from a number

of different causes as the errors are of varying magnitudes and in different directions

PPDM HOUSTON 2012

Forensic Geodetics of One Well Location (US GOM)

• Cost of well was …… • Followed the data from G&G through

Drilling Ops • 486 documents with location (x,y) • 40% had no datum stated • NAD 27, NAD 83, WGS 84 datums are

all relevant for this process • In UTM grid, positioning difference

is? 19


N

NAD 27

NAD 83 NAD 83 datum Lat. 27º 00’ 37.49” N Long. 92º 14’ 10.97” W

NAD 27 datum Lat. 27º 00’ 36.47” N Long. 92º 14’ 10.66” W

NAD 27 minus NAD 83: Latitude = -1.02” Longitude = -0.31”

Ignoring Geodetic Datums for a Single Well Position in the Central Gulf of Mexico


N

NAD 27

NAD 83

199 m or 652 ft



NAD 27 minus NAD 83: Latitude = -1.02” Longitude = -0.31”

UTM Zone 15N Northing = -198.57 m (-651.47 ftUS) Easting = + 10.19 m (33.44 ftUS)

Different Datums for a Single Well Position in the Central Gulf of Mexico


Russia Land Seismic in the Wrong Map Projection → 950m errors

Example courtesy of Satellite Imaging Corporation

PPDM HOUSTON 2012

Geodesy: Essentials for Geospatial Data

• Geodetic Datum

• Map Projection

• Vertical

• Orientation

• Unit of Measure

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PPDM HOUSTON 2012

Geodesy 101

• Geodetic Datum

• Map Projection

• Vertical

• Orientation

• Unit of Measure

• Coordinate Reference System

• Grid, X and Y

• Elevation, Height, Depth

• North, Direction

• Foot or Meter

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PPDM HOUSTON 2012

Terrain

Geodetic Reference Surfaces

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Geoid Equipotential surface which

approximates to MSL

Geoid Normal to Geoid

a b

Ellipsoid Surface where Computations are made

1/f = a/(a-b)

Ellipsoid

Normal to Ellipsoid

h H

N

N=h-H

Source: APSG

PPDM HOUSTON 2012

The one thing you need to know about a Geodetic Datum is..

YOU NEED ONE

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Geodetic Terminology (ISO compliant)

• Topography / Terrain (= actual earth surface) • Geoid (= equipotential earth’s surface ~ MSL) • Ellipsoid / Spheroid = Mathematical figure used for

computations • Coordinate System (only a system of axes in ISO) • Prime Meridian (the meridian that is set to zero for a

given datum) • Geodetic Datum

– Local / Astrogeodetic Datums – Geocentric Datums / Global Datums

• Ellipsoid and Datum are NOT synonyms!

– Assuming otherwise can lead to costly mistakes

PPDM HOUSTON 2012

Prime Meridian = 0 degree longitude

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Major World Datum Blocks

North America European Pulkovo

South America Cape Arc Australian

Tokyo Indian

Over 350 well-defined Horizontal Datums worldwide!

Samboja

DGN95

GDA2000

JGD2000

Hanoi

Hu Tzu Shan Hong Kong Indian 54

AGD84

Kandawala

Tokyo

AGD66

Pulkovo

Herat Xian 1980

Gan 1970

Batavia Bukit Rimpah

Luzon Timbalai Kerta

u

Indian 60

Kalianpur 62

Beijing 54 Iwo Jima 45

ID74

VN2000 Kalianpur 37

DGN95


Geodetic Datum Examples

Datum Origin PLUS Reference Ellipsoid = Datum 11 main stations + Airy = OSGB36 Many points (global) + WGS72 ellipsoid = WGS72 1591+ points (global) + WGS84 ellipsoid = WGS84 Potsdam + International 1924 = ED50 La Canoa, Venezuela + International 1924 = PSAD56 Meade's Ranch, KS + Clarke 1866 = NAD27 Many pts, North America + GRS80 = NAD83 Herstmonceaux, UK + Airy = OS(SN)80 Manoca Twr, Cameroon + Clarke 1880 IGN = Manoca Minna Station, Nigeria + Clarke 1880 RGS = Minna Many points (global) + GRS80 = ITRF yyyy

Where yyyy is adj. year

PPDM HOUSTON 2012

Hierarchy of Geospatial Data or Mapping

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Geodetic Datum (includes ellipsoid) is the Foundation

X,Y,Z Cartesian and Lat Long, Ht

Equator

Zp

Xp Yp

P hp

Ellipsoid

λp Φp

stable Unstable w/o Datum

Map Projection is a derivative of the Datum

Easting, Northing, X,Y

Elevation (above MSL)

Source: APSG


Remember . . .

Knowing the map projection and all its parameters is insufficient (even if the ellipsoid is known)!

…Unless associated with a Geodetic Datum

The Map Projection coupled with a Geodetic Datum makes a Projected Coordinate Reference System (or ProjCRS)



Tools GNSS (GPS) Positioning GIS Mapping Geoscience Software Engineering Software

Knowledge Basic Geography College, University Industry Training Learning & Development

Techniques Standards & Practices Procedures & Workflows Quality Control Processes Continuous Improvement

Project Work


Coordinate Formats and Precision

Meridians

Parallels

Longitude (λ) - 180° ≤ 0 ≤ 180°

Software Convention: N,E (+); S,W (-)

Latitude () - 90° ≤ 0 ≤ 90°

Precisions shown consistent to centimeter level Degrees Minutes Seconds (DD MM SS.sss H) 34° 27' 17.453" N 118° 31' 32.684" E Degrees Decimal Minutes (DD MM.mmmmm H) 34° 27. 29088' N 118° 31. 54473‘ E

Decimal Degrees * (DD.ddddddd H) 34.2881814° N 118.5257456° E

0°

NP

Equator

Ellipsoid

* difference is about 20 kilometers (12 statute miles) if DD.MMSSsss thought in DD.ddddddd format!

DMS in Sexigesimal Format (DD.MMSSssss) 34.2717453° N 118.3132684° E

PPDM HOUSTON 2012

Coordinate Transformations are not trivial

35 Source: OGP EPSG Registry


More Confusion in Geodesy

Reference Orientations: (5 types of North) • True North = direction of the meridian through a point • Magnetic North = differs from True N by Declination • 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


Magnetic Declination

Montana 45N, 112W on Jan 18, 2004 14.35º E changing by 6' West per year

Brazil (Campos) 23S, 41W on Feb 24, 2004 22.4º E changing by 6' East per year


Downhole Surveys: Varying “North” References Orientation

• From various well documents and databases – Casing MWD: Magnetic (referenced to Magnetic North) – Below Casing: Inertial (referenced to True North) – Rig orientation: (referenced to Grid N or True N?)

• When data are merged: – Was the magnetic data adjusted to grid or true N? – Has the rig orientation used the same North reference? – Is all this documented for other departments / users?

• Do specifications lead to consistent results? • Was there QC of the onsite methods and data? • Is there a clear and informative report?

PPDM HOUSTON 2012

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PPDM HOUSTON 2012

39 Units of Measure EPSG Geodetic Registry

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More Confusion in Geodesy

Reference Units of Measure (many types of feet and 2 types of meters) • Biggest Problem = U.S. Survey Ft vs. International Ft • Some 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 (with

almost as many variations as the foot to meter relationships)

PPDM HOUSTON 2012

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!

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PPDM HOUSTON 2012

Data Tools

Knowledge Techniques

Zone of the Geodetic Quagmire

43

PPDM HOUSTON 2012



Geodetic Integrity:

The Essential Basics for Data Managers and Users

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Michael Barnes

www.apsg.info

PPDM Data Management Symposium March 7, 2012 · PDF filePPDM Data Management Symposium March...

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