A Growing Concern for the Geospatial, Land
Surveying and Mapping Communities
Presented by:
The California GIS Council's
Geodetic Control Work Group (CGWG)
1)
Introduction of the GCWG.
2)
Importance of a common reference frame.
3)
Why GIS data needs Geodetic Control.
4)
Geodetic control resources in California.
5)
What's Next?
 The California GIS Council authorized formation of the
Geodetic Control Work Group in November 2009.
 The work group was assembled in March 2010 & chaired by
Marti Ikehara, retired NGS Advisor to California.
 A charter and work plan were approved by the CA GIS Council
in April, 2011.
 Bi-monthly or Monthly
teleconferences and meetings.
 Outreach subcommittee to give presentations.
 The CA GCWG operates independently of other groups.

Chartered by CA GIS Council in April, 2011
Current Chair, Scott Martin – Caltrans
John Canas - CSRC
Landon Blake – O’Dell Engineering, Inc.
Tom Dougherty - S.C.V.W.D
Justin Height - Penfield & Smith, ACEC, CA
Ryan Hunsicker – Sn.Bdo.Cnty, CLSA
Bruce Joffe - GIS Consultants
Ric Moore – BPELSG
Neil King – PhotoScience, Inc. ACEC-CA
Mark Turner- Caltrans
Michael McGee - McGee Surveying, CLSA
Kristin N. Hart - Padre Associates, Inc.
Reg Parks - Santa Rosa Junior College, PVTS

GCWG Sub-committees
o Strategic Plan Subgroup
o Data Standards Subgroup
o Outreach / Communication Plan
Charter documents (√), Strategic Plan, Work Plan (√),
approved by CA GIS Council.


Outreach Plan to elicit feedback

Geodetic control data sources & standards for metadata.
Recommendations for standards, stewardship, and
funding for geodetic theme and infrastructure.


Strategic Plan and Business Plan for adoption by the CGC.
Policy and technical statements for utilization and
alignment of the GC theme by other GIS themes.

1)
Introduction of the GCWG.
2)
Importance of a common reference frame.
3)
Why GIS data needs Geodetic Control.
4)
Geodetic control resources in California.
5)
What's Next?
(Reprioritized to
#1 in 2014 FGDC SDI
Governmental
Boundaries
Hydrography
Geodetic Control
Transportation
Cadastral
Elevation
Ortho Imagery
GIS Stacks Map Layers
Numerous GIS
layers are employed
in:
• land development
• construction
• asset mgmt.,
• land analyses
• map display
• etc.
They are updated
frequently.
By whom and on
what coordinate
system?
Is that
1928845.23, 6354191.85?
No, wait, that’s
Where’s the pinche
control layer?
1928835.23,
6354192.85
Geodetic Control is (or should be) the
foundation for all geospatial products
Source: Zurich-American Insurance Group
Without Geodetic Control as a basemap layer, GIS
themes may not ALIGN well
x1b,y1b,z1b
x2b,y2b,z2b
x3b,y3b,z3b
Same Datum & Coordinate System
x1a,y1a,z1a
x2a,y2a,z2a
x3a,y3a,z3a
Every layer is expressed in the same coordinate system as the CONTROL LAYER.
Importance of a common reference frame.




Surveys – CCS, PRC (Horiz. & Vert.), FEMA & Elevations
Civil Engineering
Residential, Municipal, Statewide Construction,
Transportation, Hydrography, Hydrology


Public Safety

GIS Projects -- multiple source layer control
Future / Science FACTion / 3D / 4D


First responders, Fire and Rescue, Seismic Early Warning
aerial guidance, vehicle guidance, augmented reality
1)
Introduction of the GCWG.
2)
Importance of a common reference frame.
3)
Why GIS data needs Geodetic Control.
4)
Geodetic control resources in California.
5)
What's Next?

State mandated County GIS data submission

Parcel Data maintained by County Surveyor

All Counties use the same coordinate system
County “A”
County “B”
County “C”
County “D”
County “A”
County “A”
County “B”
County “A”
County “C”
County “B”
County “A”
County “C”
County “B”
County “D”
1)
Introduction of the GCWG.
2)
Importance of a common reference frame.
3)
Why GIS data needs Geodetic Control.
4)
Geodetic control resources in California.
5)
What's Next?

Passive Monuments:
 Monuments set in the ground that require
periodic re-observation to determine accurate
relative position.
 Position only valid at the time of survey.

Active Monuments (CGPS)
 CGPS station collects data 24 hours a day and
its relative position is continually monitored.
 Positions that have become degraded due to
earthquakes, subsidence and crustal motion
can be updated.
1)
Introduction of the GCWG.
2)
Importance of a common reference frame.
3)
Why GIS data needs Geodetic Control.
4)
Geodetic control resources in California.
5)
What's Next?






Modern societies need GIS/geospatial data to analyze and manage a
wide variety of resources.
Geospatial data comes from different sources, but should have one
thing in common: the frame of reference.
Frame of reference must be defined by an accessible and maintained
geodetic control network.
Passive networks have limited value: difficult access, expensive to
maintain, vulnerable to movement.
Active networks (CGPS) are the future, and are the only viable and
meaningful basis for geodetic infrastructure in California.
California’s active geodetic network is in danger because
 funding sources are uncertain
 lack of understanding of importance
 no definitively appointed permanent steward (i.e. agency or
organization with reliable annual funding)

GCWG appointed by California GIS Council to study
and advise on geodetic control data standards and
infrastructure.

Assessment of situation warrants immediate action:
outreach and information gathering.

We will recommend solutions per our charter…...as
soon as we figure out what to recommend.

Meanwhile, we need your help with ideas and
spreading the word.
Education/Information
 Presentations, articles, and letters
 Educate surveyors & GISP’s on importance of geodetic control
 Be visible and accessible at survey/GIS conferences & meetings
 Talk and exchange ideas – someone may already know
 Research what other states have done – don’t reinvent wheel
Legislation
 All official California GIS data to be tied to the geodetic control
 Create new agency? Fund existing agency?
Advocacy

Form technical and financial partnerships/consortiums

Seek funding sources

Lobbying and promoting
A Growing Concern for the Geospatial, Land
Surveying and Mapping Communities
Thank you for your attention,
participation and feedback!
Presented by:
The California GIS Council's
Geodetic Control Work Group (CGWG)
Contact:
Ryan Hunsicker
Scott Martin
rhunsicker@dpw.sbcounty.gov
scott.martin@dot.ca.gov