2003 Ground Control Report - St. Johns County Government

REPORT OF GPS GROUND CONTROL SURVEY:
FOR TOPOGRAPHIC AERIAL MAPPING PROJECT 2003
St. Johns County, Florida
Prepared for:
St. Johns County Public Works Department
4020 Lewis Speedway
St. Augustine, FL 32084
by:
WOOLPERT LLP
Florida Certificate of Authorization # 6777
600 Brickell Ave, Suite 801
Miami, Florida 33131
(305) 358-1565/fax: (305) 358-6564
prepared by:
Scott A. Riggs, PSM
Florida Professional Surveyor and Mapper # 6160
Summary of Contents
Section 1: Report of GPS Ground Control Survey: For Topographic Aerial Mapping Project 2003
Summary of Contents ................................................................................................................................ 1
Introduction................................................................................................................................................ 2
Project Area ............................................................................................................................................... 2
Purpose....................................................................................................................................................... 2
Date of Survey ........................................................................................................................................... 2
Monumentation .......................................................................................................................................... 2
Methodology .............................................................................................................................................. 3
Datum Reference ....................................................................................................................................... 3
GPS Data Field Processing ........................................................................................................................ 3
GPS Data Office Processing ...................................................................................................................... 3
GPS Adjustments ....................................................................................................................................... 4
Accuracy Specifications............................................................................................................................. 5
Section 2: New Control Station Coordinate Listing and Existing Control Coordinate Comparison List
Section 3: New Control Station Recovery Information Sheets
Section 4: Existing Control Station Information
Section 5: Map of Final Survey Control Layout
Woolpert – 60581
Issue Date: July 7, 2003
Report of GPS Ground Control Survey 2003
St. Johns County Public Works Department
Page 1 of 5
Introduction
This report contains a comprehensive outline of the GPS Ground Control Survey that supported the St.
Johns County Topographic Aerial Mapping Project. All surveys were performed in such a way as to
achieve Second-Order GPS horizontal, and Third-Order GPS vertical as outlined in Geometric Geodetic
Accuracy Standards and Specifications for Using GPS Relative Positioning Techniques, Version 5.0, of
August 1, 1989, published by the Federal Geodetic Control Committee (FGCC).
Project Area
The project area encompasses approximately 700 square miles of the St. Johns County, Florida.
Purpose
The purpose of this survey was to establish three-dimensional coordinates for one hundred six (106)
photogrammetric ground control stations throughout St. Johns County. In addition to establishing new
ground control stations throughout St. Johns County, Woolpert also was required to incorporate eightythree (83) existing St. Johns County control stations. These ground control stations, in conjunction with
aerial triangulation, will be used for the purpose of photogrammetric mapping (orthophotography with
contours). Also, in conjunction with LiDAR acquisition and processing, these ground control points will
be used for generation of DTM data and one foot contours.
Date of Survey
All ground control field operations took place between January 13 and February 3, 2003.
Monumentation
Woolpert confirmed, in the field, the optimal locations needed for aerial triangulation and targeted a total
of 189 control stations. Each control station was pre-targeted with a 7-foot by 7-foot by 1-foot fiberglassreinforced cloth material or latex paint prior to taking aerial photography. Woolpert established one
hundred six (106) new control stations, forty-eight (48) of which were monumented with the Berntsen
model F-130 monument. In addition, forty-five (45) control stations established by Woolpert consisted of
either a 5/8-inch diameter by 24-inch long iron rebar with a plastic logo cap stamped, “Woolpert LLP, LB0006777”, or a Mag (PK) nail and washer stamped, “Woolpert LLP, LB-0006777”.
Woolpert also installed three (3) photo identifiable points (03-5,03-6 and 03-16) in locations that were
unsuitable for a cloth or painted target. The photo identifiable points consisted of a Mag (PK) nail, PK nail
and washer or 24-inch rebar with a plastic logo cap stamped, “Woolpert LLP, LB-0006777”. Additionally,
one (1) control station (03-67) was established using a 60d spike and plastic washer. Eight (8) of the new
photo control stations were resets of existing St. Johns County control that were destroyed or not found.
To preserve the control network, these stations were set near the locations of the destroyed control stations
and each station consisted of either a 5/8-inch diameter by 24-inch long iron rebar with a plastic logo cap
stamped, “Woolpert LLP, LB-0006777”, or a Mag (PK) nail and washer stamped, “Woolpert LLP, LB0006777”.
Woolpert – 60581
Issue Date: July 7, 2003
Report of GPS Ground Control Survey 2003
St. Johns County Public Works Department
Page 2 of 5
Lastly, one (1) of the one hundred six (106) new control stations (03-71) was found to be in the vicinity of
a Department of Natural Resources concrete monument with a brass disk, stamped “79-A56”. This station
was used instead of setting a new point in the same location.
Methodology
Rapid-Static GPS surveying techniques were used for measuring the ground control network. Rapid-Static
GPS surveying requires a minimum of two receivers to occupy stations at either end of a baseline for
approximately 5-20 minutes, depending upon baseline length, number of satellites, and satellite geometry.
This is similar in theory to static surveying, however, shorter observation time is made possible due to
advances in both hardware and software.
The survey was conducted using five (5), Woolpert-owned, Trimble Navigation 4000SSE/SSI dualfrequency geodetic GPS receivers following rapid-static survey techniques. Each observation session
utilized a 5-second sync rate, lasting between 10 - 30 minutes each.
Datum Reference
All horizontal GPS control was based on the Florida State Plane Coordinate System (East Zone),
referenced to North American Datum 1983, adjustment of 1990 (NAD83/90) expressed in U.S. Survey
Feet. The vertical datum used for this survey was the North American Vertical Datum of 1988 (NAVD88),
also expressed in U.S. Survey Feet.
GPS Data Field Processing
The field crew chief processed all session baselines each day using Trimble Navigation’s Trimble
Geomatics Office (TGO) version 1.60 baseline processor and using the broadcast ephemeris. Trimble
Navigation’s Trimble Geomatics Office (TGO) Wave Software User’s Guide (November 1999) was used
as a reference. The ratio and root-mean-square (RMS) criteria on pages 3-4 to 3-6 of the guide were
followed. Other criteria used a maximum of 10.5 percent rejections, along with float-versus-fixed deltas of
10 cm. All cases that failed to meet any of these criteria were rejected and not used. Fixed and float
solutions were obtained for all vector baselines. Daily processing allowed the field crew to discover weak
links in the network and immediately schedule re-observations of the affected baselines.
GPS Data Office Processing
The project’s GPS vector baseline reductions were completed using Trimble Navigation’s Trimble
Geomatics Office (TGO) software version 1.60. The processed baselines were then ran through a rigorous
loop closure analysis. Baselines that failed this analysis were either reprocessed or removed from the
network.
Woolpert – 60581
Issue Date: July 7, 2003
Report of GPS Ground Control Survey 2003
St. Johns County Public Works Department
Page 3 of 5
GPS Adjustments
Once the vector baseline reduction was completed for the GPS ground control network using Trimble
Navigation’s Trimble Geomatics Office (TGO) software version 1.60, Woolpert performed both
unconstrained and constrained least-squares adjustments using GEOsurv’s GEOLAB 3 version 7.26
software. Both unconstrained and constrained adjustments were computed using trivial and nontrivial
baselines.
After an acceptable unconstrained least-squares adjustment was obtained for both networks, Woolpert
performed a fully constrained least-squares adjustment by fixing the GPS networks to existing NGS and
existing St. Johns County control stations. For these surveys the following stations were held fixed:
Dimension
St. Johns County Control Stations Used
D322, DURBIN 2, FLGPS 31 and
PC01
3-D Control Stations
2-D Control Stations
NGS Control Stations Used
G022, G027, G037, G057, G061, G067,
G091, G107, G119 and TID1
PALM, 872 0596 TIDAL 1
B071 and KITTLESON PRIM MK
DUPONT 2, ELLZEY, P405,
Q 321, Q 323 and VILANO
RESET
1-D Control Stations
The information for the existing St. Johns County control stations was obtained from a booklet provided
by the St. Johns County Development Services Department, Surveying and Mapping Program, entitled
“Survey Report For St. Johns County, Florida Geodetic Control Project, September 1994 through February
1999”. The description sheets for these control stations can be found in Section 4 of this report. For a
detailed summary of the control stations that were held fixed and comparison coordinates for control
stations that were not held fixed, please refer to the table found in Section 2 of this report.
Final Coordinates and Survey Control Layout
The final NAD83/90 State Plane Coordinates (Florida, East Zone) and elevation referenced to NAVD88
for the ground control network stations are presented in Section 2 in U.S. Survey Feet. For the survey
control layout, refer to Section 5 and the attached map entitled, “Final Survey Control Layout”.
Woolpert – 60581
Issue Date: July 7, 2003
Report of GPS Ground Control Survey 2003
St. Johns County Public Works Department
Page 4 of 5
Accuracy Specifications
The final constrained adjustment indicates that the GPS survey exceeds criteria for a Second-Order
horizontal GPS survey, and Third-Order vertical GPS survey as defined in “Geometric Geodetic Accuracy
Standards and Specifications for Using GPS Relative Position Techniques” (August 1, 1989) as published
by the FGCC.
NOTICE:
NOT VALID WITHOUT THE SIGNATURE AND ORIGINAL RAISED SEAL OF A
FLORIDA LICENSED SURVEYOR AND MAPPER. THIS REPORT IS NEITHER
FULL OR COMPLETE WITHOUT THE ATTACHED MAP. ADDITIONS OR
DELETIONS TO SURVEY MAPS AND REPORTS BY OTHER THAN THE SIGNING
PARTY OR PARTIES IS PROHIBITED WITHOUT THE WRITTEN CONSENT OF
THE SIGNING PARTY OR PARTIES.
Surveyor and Mapper in Responsible Charge:
Scott A. Riggs
Professional Surveyor and Mapper
License Number: 6160
Signed: ____________________________________
Woolpert – 60581
Issue Date: July 7, 2003
Report of GPS Ground Control Survey 2003
St. Johns County Public Works Department
Seal:
Page 5 of 5