1. The Woodlands Waterway Marriott
3-D Global Spatial Data Model Continuing Education Seminar Instructor: Earl F. Burkholder, PS, PE
Sponsored by the ASCE
Geomatics Division
Richard Popp, PE – Chair
1:00 to 5:00 p.m., March 21, 2011
The Woodlands Waterway Marriott
At SPAR 2011 – Houston, Texas

2. 3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F
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.

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

4. Types of and generating spatial data
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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)

5. Resources and References
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
Resources and References
Web site –
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
GPS: Charting the Future
GIS for the 21st Century

8. What is the future of 3-D? Exciting! Reasons for attending?
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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!

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

10. History is ‘recent’ but old:
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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 GPS made it practical.

11. Flat earth and 2D maps – this is our history.
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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

12. Where is origin for your coordinate system?
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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!

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

14. Geodetic & geographic (ellipsoidal/spherical)
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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?

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

16. Basic Elements and Conventions: 2-D x & y, plane Euclidean geometry
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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

17. Absolute with respect to coordinate system
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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.)

18. How are spatial data generated? Measurement of physical quantities.
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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

19. Models for spatial data manipulation: Conventional 1-D and 2-D - COGO.
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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: feet + 50 ppm
- Geodetic (FGDC 1998)
- Other (many)

20. Equations and geometry 3-D integrated data base (stores it all)
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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.

21. Stochastic Model - Spatial data accuracy:
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
Stochastic Model - Spatial data accuracy:
Standard deviation
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?

22. Tie into Use of Real-Time Networks
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
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”

23. Additional Information on the 3-D GSDM
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
Additional Information on the 3-D GSDM
Defining document for the GSDM
ION presentation containing equations etc.
Spatial Data Accuracy
Description for surveyors

24. Geodetic control using static observations
3-D Global Spatial Data Model (GSDM) Seminar Presented by: Earl F. Burkholder, PS, PE – Las Cruces, New Mexico
Example GSDM Projects
Geodetic control using static observations
Leveling using GPS and geoid modeling
Property (boundary) survey using the GSDM