3-D Global Spatial Data Model Continuing Education Seminar Instructor: Earl F. Burkholder, PS, PE Sponsored by the ASCE Geomatics Division Richard Popp,

3-D Global Spatial Data ModelContinuing Education Seminar

Instructor: Earl F. Burkholder, PS, PE

Sponsored by the ASCE

Geomatics DivisionRichard Popp, PE – Chair

1:00 to 5:00 p.m., March 21, 2011 The Woodlands Waterway Marriott

At SPAR 2011 – Houston, Texas

3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico

The Global Spatial Data Model (GSDM) provides a way to organize concepts for a better understanding of 3-D spatial data.

The GSDM does not take anything away from what you already know but adds valuable insight into the relationships between coordinate systems.

The GSDM will enable you to become more comfortable with routine use of 3-D data.


• Welcome, Introductions, and Overview• Big picture reason for GSDM – single origin• History and background – with Q and A• Three coordinate systems:

1. Geodetic, traditional latitude/longitude

2. Geocentric, Earth-centered Earth-fixed

3. Local, flat earth• Basic elements and conventions


• Types of and generating spatial data• Models for spatial data manipulation

1. Functional Model, equations and geometry

- Flat earth includes horizontal & vertical

- Geodetic latitude/longitude/height

- Geocentric, earth-centered earth-fixed

2. Stochastic Model, standard deviations

- Spatial data accuracy

- Error propagation • Tie into use of real-time GPS networks (RTN)


Resources and References• Web site – http://www.globalcogo.com

1. Articles

2. Overheads

• Book – The 3-D Global Spatial Data Model

1. Published by CRC Press 2008

2. Google Global Spatial Data Model

• National Academy of Public Administration 1. 1995 GPS: Charting the Future

2. 1998 GIS for the 21st Century

http://www.globalcogo.com/

http://google.com/


• This is where we jump into the nitty- gritty. Any questions before we get started?

• What is the future of 3-D? Exciting!• Reasons for attending?• Certificates and continuing education• Registration boards • Protecting the public• We do it because it is the thing to do!


• Big Picture Justifications:

- With electronic revolution spatial data are:

1. Digital

2. Three-dimensional

- Measurement systems collect 3-D data

- Spatial data are stored in computer files

- Many disciplines work with spatial data

- Think globally, work locally

- Spatial data accuracy is critical


History is ‘recent’ but old:• Computers and electronic storage foster use

of an integrated 3-D data base.• Many applications still treat horizontal &

vertical separately. It is our view of the world. • René Descartes (1596 – 1650) formalized

geometry, Discourse on the Method, 1637.• Global 3-D control polyhedron was proposed

by Burns in 1878. GPS made it practical.


Background• Flat earth and 2D maps – this is our history. • Implications of curved earth (How do you know the earth is not flat?)• Map projections: - Portray curved earth on a flat surface - Strictly 2-D mathematical model• The Digital Revolution includes: - Computers, electronics, and gadgets. - Photogrammetry, GPS/GNSS, Scanning


• Where is origin for your coordinate system?

- Local/assumed (not much ‘big picture’ use)

- State plane, northings & eastings, unique?

- Geodetic latitude/longitude, curvilinear

- Geocentric rectangular center of Earth• Elevation, origin is geoid (or mean sea level).• Non-compatible origins is a huge problem!


Three different coordinate systems:

http://www.globalcogo.com/CR002.pdf

• Local, many spatial data users.

- x & y or north & east flat-earth values

- Is origin well defined or monumented?

- Elevation is ‘up’

- Vertical origin is mean sea level (geoid).

http://www.globalcogo.com/CR002.pdf


http://www.globalcogo.com/GM012.pdf

• Geodetic & geographic (ellipsoidal/spherical)

- Computations on ellipsoid or sphere.

- Latitude and longitude curvilinear values.

- Position in degrees-minutes-seconds.

- Equations are cumbersome and complex.

- Third dimension is ellipsoid height or

altitude. Is that elevation?




Geocentric earth-centered earth-fixed (ECEF) - Rectangular coordinates in meters. - Origin at earth’s center of mass. - X and Y are in plane of equator. - Z axis is parallel to spin axis of earth. (there is no “up” in ECEF!) - Uses rules of solid geometry - Vector algebra & matrices easy & efficient - Rotation matrix makes ECEF practical! - Eastings/northings same as lat’s and dep’s



Basic Elements and Conventions:• 2-D x & y, plane Euclidean geometry• 3-D condo surveys, plan & profile, topo maps• Geodetic latitude, longitude, height• Geocentric earth-centered earth-fixed (ECEF) (Rules of solid geometry & vector algebra)• Units for angles and distances• Conventions – right handed rule e/n/u


Types of spatial data• Absolute with respect to coordinate system

(Often used by GIS for spatial data analysis)• Relative with respect to another point

(Often used by surveyors & mappers etc)• Reference frames and datums

(Spatial data accuracy is an important issue whether using absolute or relative data.)


How are spatial data generated?• Measurement of physical quantities.• Direct vs indirect measurements• Pacing, tape, total station, leveling, GPS,

photogrammetry, remote sensing ‘Italian job’• How are spatial data components computed?• Context determined by: - Orientation; azimuth, gravity, other. - Scale; units – chains, feet, meters, other


Models for spatial data manipulation:• Conventional 1-D and 2-D - COGO.• Evolution of 3-D data• Analog to digital• Error propagation – calculus rates of change• Standards and specifications: - ACSM/ALTA: 0.07 feet + 50 ppm - Geodetic (FGDC 1998) - Other (many)

http://www.fgdc.gov/standards/standards_publications/


Functional Model• Equations and geometry • 3-D integrated data base (stores it all)• Working from whole to part - hiearchy• Coordinate systems• Datums• Networks • Rotation matrix provides flat earth • 2-D COGO is a sub-set of 3-D X/Y/Z.


Stochastic Model - Spatial data accuracy:• Standard deviation http://www.globalcogo.com/SD002.pdf

• With respect to what? • How good is good enough?• Error propagation Σ = J Σ Jt (Matrix form)• Confidence levels• 95% at 2 sigma level is standard practice.• OPUS – how good is it?

http://www.globalcogo.com/SD002.pdf


Tie into Use of Real-Time Networks• The GSDM is equally applicable to:

- Any 3-D datum (but only 1 at a time), i.e.:

1. ITRF

2. WGS 84

3. NAD 83• Any brand of GPS equipment:

- Vendors are fully aware of ECEF values

- Equations for GSDM are “open”


Additional Information on the 3-D GSDM• Defining document for the GSDM http://www.globalcogo.com/gsdmdefn.pdf

• ION presentation containing equations etc. http://www.globalcogo.com/ionpaper.pdf

• Spatial Data Accuracy http://www.globalcogo.com/accuracy.pdf

• Description for surveyors

http://www.globalcogo.com/psgsdm.pdf

http://www.globalcogo.com/gsdmdefn.pdf

http://www.globalcogo.com/ionpaper.pdf

http://www.globalcogo.com/accuracy.pdf

http://www.globalcogo.com/psgsdm.pdf


Example GSDM Projects• Geodetic control using static observations http://www.globalcogo.com/nmsunet1.pdf

• Leveling using GPS and geoid modeling http://www.globalcogo.com/ReilElev.pdf

• Property (boundary) survey using the GSDM http://www.globalcogo.com/3DGPS.pdf

http://www.globalcogo.com/nmsunet1.pdf

http://www.globalcogo.com/ReilElev.pdf

http://www.globalcogo.com/3DGPS.pdf

3-D Global Spatial Data Model Continuing Education Seminar Instructor: Earl F. Burkholder, PS, PE Sponsored by the ASCE Geomatics Division Richard Popp,

Documents

d data spatial data

d spatial data

spatial data models

spatial data manipulation

spatial data users

d data base

d mathematical model

pe las cruces