H 88 = h 83 – N 03. THE TECHNOLOGY SWEET SPOT SBAS: 2 M H, 6 M V, 0.3 M SMOOTHED H, CHEAP...
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Transcript of H 88 = h 83 – N 03. THE TECHNOLOGY SWEET SPOT SBAS: 2 M H, 6 M V, 0.3 M SMOOTHED H, CHEAP...
H88 = h83 – N03
THE TECHNOLOGY SWEET SPOT• SBAS: 2 M H, 6 M V, 0.3 M SMOOTHED H, CHEAP• COMMERCIAL DGPS: FEW DM, $$• USCG BEACON: METER+, CHEAP• CORS/OPUS: 2 CM h, 5 CM H POST PROCESSED• DIFFERENTIAL LEVELING: 2-4 CM, LABOR/TIME INTENSIVE, $$$• GEODETIC LEVELING: mm, LABOR/TIME INTENSIVE, $$$$$• USER BASE RTK: 2-4 CM H, 2-5 CM V, REQUIRES INITIAL
INVESTMENT, OUTCOME KNOWN IN FIELD• RTN: 3-4 CM H, 5-7 CM V, REQUIRES INITIAL INVESTMENT(BUT ½ OF
RTK), OUTCOME KNOWN IN FIELD• AERIAL MAPPING: .10 M H, .20 M V, $$$• LIDAR: 0.10 – 0.3 M V• SATELLITE IMAGERY: 0.5 METER H RESOLUTION, 3 M LOCATION, $$$• LOW ALTITUDE AERIAL IMAGERY: 2-4 CM H, 3-5 CM V, $$$• TERRESTRIAL LASER SCANNING: PROJECT SITES ONLY, 0.015 M H,
0.02 M V, REQUIRES INITIAL INVESTMENT
≥200 RTN WORLDWIDE≥80 RTN USA≥37 DOT
ACADEMIC/SCIENTIFICSPATIAL REFERENCE CENTERSVARIOUS DOTS + MACHINE GUIDANCECOUNTYCITYGEODETIC SURVEYS (NC, SC)MANUFACTURERSVENDOR NETWORKSAGRICULTUREMA & PA NETWORKS
RTN IN THE USA(JAN 2010)
RT FOR ORTHO HEIGHTSADVANTAGES:• LESS TIME- SECONDS ON POINT• LESS LABOR- NO POST PROCESSING, MINIMAL PERSONNEL• LESS EQUIPMENT – ONLY ONE RT UNIT NECESSARY WITH RTN• = LESS $$$
• USER KNOWS POSITION HAS BEEN CAPTURED AT REQUIRED PRECISION
• “GOOD” RELATIVE PRECISION IN HOMOGENEOUS TERRAIN AND USING THE SAME INITIALIZATION
• NEW GEOPOTENTIAL DATUM WILL BE ACCESSED THROUGH ACTIVE STATIONS
DISADVANTAGES:• LESS ACCURACY THAN LEVELING OR STATIC GNSS• REQUIRES ADEQUATE USER KNOWLEDGE OF ALL EFFECTS ON RT GNSS POSITIONING
• Access to accurate, reliable heights nationally- Geoid quality, New geopotential datum via active stations
• Consistent Standards across the nation- RTN validation, RTN guidelines
• Consistent Results. Data, technology, and tools that yield regardless of terrain and circumstances- Alignment to NSRS
• Maintainable system/process that will stand the test of time – ARP velocities, Integrity monitoring, User gets new datum via RTN
RT IN RELATION TO GOALS OF NHMP
NEW APPLICATIONS IN ”HIGH-ACCURACY” REAL-TIME POSITIONING
• GIS – INFRASTRUCTURE, SIGNAGE, ENVIRONMENTAL, PHOTO CONTROL
• AGRICULTURE• MACHINE GUIDANCE• DEFORMATION MONITORING• TECTONIC/SEISMIC STUDIES• NAVIGATION TO/FROM PORTS• REMOTE SENSING/MAPPING – LIDAR• FAA – NAVIGATION, LANDING, TAXIING• (WEATHER SCIENTISTS – CO-LOCATED RT
IONO/TROPO SENSORS)
PRECISION VS. ACCURACY
•“PRECISION” IS A COMPUTED STATISTICAL QUANTITY TO THE SOURCE OF THE MEASUREMENT - ALIGNMENT TO THE RTN OR PASSIVE MARK BASE SHOWS PRECISION OF THE OBSERVATION (PER THE DATA COLLECTOR).
•“ACCURACY” IS A COMPUTED STATISTICAL QUANTITY TO THE REALIZATION OF THE DATUM - ALIGNMENT OF THE RTN OR PASSIVE MARK BASE TO THE NSRS SHOWS ACCURACY (PER ESTABLISHED METHODOLGY)•
• B ≥ 4 H & V, KNOWN & TRUSTED POINTS?• B LOCALIZATION RESIDUALS-OUTLIERS?• B DO ANY PASSIVE MARKS NEED TO BE
HELD?• RT BASE WITHIN CALIBRATION (QUALITY TIE
TO NEAREST CALIBRATION POINT)?• B SAME OFFICE & FIELD CALIBRATION USED?
FYI: GNSS CAN PROVIDE GOOD RELATIVE POSITIONS IN A PROJECT WHILE STILL NOT CHECKING TO KNOWNS IN AN ABSOLUTE SENSE
BLUNDER CHECKING POINTS WITH OPUS-RS
NGS SINGLE BASE GUIDELINES
http://www.ngs.noaa.gov/PUBS_LIB/NGSRealTimeUserGuidelines.v1.1.pdf
• LEGACY EQUIPMENT
• NO CELL COVERAGE
• NEW RT CLOSEST BASE NETWORKS
• MACHINE GUIDANCE AND PRECISION AGRICULTURE USE
RTN GUIDELINES FOR GNSS POSITIONING–WILL NOT SPECIFY OR
DEFINE A STANDARD, BUT WILL HELP
ADMINISTRATORS AND USERS TO BE AWARE OF
ALL THE ISSUES INVOLVED WITH THIS NEW TECHNOLOGY
60+ CONTRIBUTORS:
•NGS ADVISORS•DOT
•STATE GEODETIC SURVEYS
•GNSS MANUFACTURERS•SRCs
•BLM, NPS
THOUGHTS ON ORTHO HEIGHTS ON RTN ARP
• LEVELING TO ARP CREATES A NEW BM EASILY USED IN HT MOD PRACTICES
• DENSIFIES GNSS ON BENCH MARKS = BETTER HYBRID GEOID MODEL
• ARP MONITORED 24/7/365 UNLIKE PASSIVE MARKS• MANY STATE DOTs ARE LEVELING TO THEIR RTN ARP• ROVER HEIGHTS STILL DEPENDENT ON GEOID MODEL FOR
ORTHOS• BY ESTABLISHING PASSIVE BMs AT RTN SITE, ELLIPSOID
DIFFERENCE CAN PRODUCE ARP ORTHOS (IF DESIRED) – BUT THIS EFFECTIVELY GIVES A MEANS OF MONITORING THE PASSIVE BM USING THE RTN STATION BECAUSE THE ARP POSITION IS ALWAYS KNOWN.
NTRIP & RTCM-IMPROVING 3D POSITIONING WITH
NEW MESSAGES
Standard Solution (RMS:21 mm)Optimized Solution (RMS:13 mm)
RTCM Paper 014-2007-SC104-462
Herbert Landau, Xiaoming Chen, Adrian Kipka, Ulrich Vollath - Trimble Terrasat GmbH
Improving RTK with RTCM Network Residual Messages
2
Positioning improved by up to a factor of 2Initialization time reduced by 30%
RTN RESIDUAL RTCM 3.x MESSAGE TYPES
https://ssl29.pair.com/dmarkle/puborder.php
STATE SPACE RTCM 3.x MESSAGE TYPES
EMERGING NGS ACTIVITIES…..
POSSIBLE METHODS OF RTN VALIDATION•OPUS-PROJECTS – NGS APPROVED PROGRAM TO VALIDATE A RTN ADJUSTMENT THAT WAS PERHAPS ACCOMPLISHED WITH GNSS MANUFACTURER’S SOFTWARE OR ANOTHER PROGRAM. •OPUS-S – 3 OR 10% OF RTN ARE NGS CORS WHICH THEN GENERATE OPUS-S SOLUTIONS ON ALL OTHER RTN REFERENCE STATIONS. THESE CAN BE PUSHED TO NGS AND PUBLISHED AS 60 DAY PLOTS, OR MAINTAINED ON A PUBLIC SITE AT THE RTN ADMINISTRATION LOCALE.• FIDUCIAL STATIONS - HIGH STABILITY MARKS ARE CONSTRUCTED WITHIN A RTN. GNSS STATIC PROVIDES X,Y,Z. GEODETIC LEVELING PROVIDES NAVD 88. STATIONS MAY BE BLUE BOOKED. USERS CAN THEN TEST THEIR ROVERS AT THE MARKS TO COMPARE THEIR RESULTS FROM THE RTN WITH THE PUBLISHED VALUES. PILOT PROGRAMS PLANNED IN OREGON AND LOUISIANA.• LETTER OF CERTIFICATION - RTN ADMINISTRATOR SENDS A STATEMENT CERTIFYING THAT AS OF A PARTICULAR DATE THE RTN IS ALIGNED TO THE NATIONAL DATUM AT A CERTAIN LEVEL (2 CM LAT/LONG, 4 CM h ?)• NGS REVIEW - NGS DOES A PERIODICAL REVIEW OF THE RTN STATIONS AND ADJUSTMENTS
IDOP VALUES – 4 CORS EXAMPLEBEST IDOP = 1
√ N
THEREFORE, WITH 9 CORS, THE IDOP AT THE CENTROID WOULD BE .33, WITH 4 CORS IT WOULD BE .5 AT THE CENTROID
ADDITION OF RMS OF DISTANCE TO CORS CONTRIBUTING TO THE SOLUTION GIVES FINAL UNITLESS NUMBER
.87.87
.87 .87
.5
.6.7
.8
.8
.7
.6
“IDOP” :THE SUBJECT OF A PAPER BY DRS. CHARLES SCHWARZ, TOM SOLER AND RICHARD SNAY
APPLICATION FOR RTN?
ALL THESE COME INTO PLAY TO ENABLE THE STRUCTURE TO CLEAR THE BRIDGE!
•LMSL•NAD 83 •NAVD 88•BATHYMETRY•CHART DATUM•BRIDGE DYNAMICS•BRIDGE DIMENSIONS•SHIP SQUAT•SHIP DIMENSIONS
KNOW YOUR METADATA- UNIFYING THE VERTICALS TO A COMMON DATUM
SC – VRS Network
To Support Surveying and Machine Control
Presentation Overview
• Introduction• VRS Network Design• Antenna Mounting Designs• Server Network Design• Modeling• Network Testing• Network Integrity• Practical Applications
South Carolina Geodetic Survey
Marine Transportation
HighwayConstruction
Obstruction Charting
Utilities
SurveyingEngineering
Mapping
Infrastructure
Motivating Force for a Network Application
Antenna Hardware
Stainless Steel MountFor Masonry Buildings
Self Supporting 24 Foot Tower
Tamper-Proof Leveling Head
Server Network Design
Should IT Be a Shareholder?
5
6
7
Modeling
???
I(λ,φ) = I0 +aλ∆λ + aφ∆φ
1 cm
-1 cm
2 – 12hr Multipath PlotsAreal Variant Ionospheric Model
The solution of Integer Ambiguityis influenced by external variables
Atmosphere - Tropo, IonClock Error - SV and ReceiverSV Orbit ErrorMultipathSeparation of Base and Rover
SC - VRS Network DesignVRS Is Not Built In a Day!
There Are Many Stakeholders!!They Are ALL Critical To Your Success
Test Network
11 Counties, 6700 Sq Mi, 10 VRS Base Stations, 50 Control Pts
VRS Absolute AccuracyComparison of VRS and NGS Height Mod Control
Absolute Accuracy
Meters
Allowable 2-D RMSEr 95% = 1.7308 * RMSEr = (2.0*2.0 + 0.3*0.3 + 1.2*1.2)1/2 = 2.4 cm*
Allowable 1-D RMSEv 95% = 1.9600*RMSEv = (2.0*2.0 + 0.3*0.3 + 2.4*2.4)1/2 = 3.1 cm*
Time (sec) 300 60 5
Horizontal (cm)
1.98 2.40 2.41
Vertical (cm) 2.25 2.39 2.40
*(Local Accuracy2 + Eccentricty2 + System Design2)1/2
Station SCBY
Vertical Axis -0.010 to 0.014m
Poor Choice for a Base Station!
Vertical Axis -0.04 to 0.055m
Diurnal E-W Motion of a 90 Foot Spun Concrete Tower
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0Centimeters
Each Depicted Value Is A Mean Of Two 5-Minute Observations Spaced Approximately 21 or 27 Hours Apart
95% Less Than 2.5 CM From Published Value
Results From Test Of The SC RTN to Determine Accurate Ellipsoid
Heights
Practical Applications
Tidal Datum Transfer
2 mile transfer0.05 ft uncertainty
VRS Elevation (ft) Leveling (ft) Difference4.557 4.560 0.0034.488 4.482 -0.0074.423 4.436 0.0134.656 4.649 -0.007
4.327 4.337 0.0104.528 4.528 0.0004.810 4.800 -0.0104.941 4.948 0.007
Mean/SDV 0.001/0.008
Classical Leveling vs VRS
1st Order Class 2 Leveling4 Surveyors4 days5.5km – 6mm
1 Surveyor4 hours12mm comparison
VRS Elevation (ft) Leveling (ft) Difference4.557 4.560 0.0034.488 4.482 -0.0074.423 4.436 0.0134.656 4.649 -0.007
4.314 4.265 -0.0494.327 4.337 0.0104.528 4.528 0.0004.810 4.800 -0.0104.941 4.948 0.0074.964 5.020 0.056
Mean/SDV 0.002/0.025
Comparison of VRS to Total StationRelative Accuracy
Grid Brg Angle Rt Grd Dist
TPT1 SURVEY 068/00/55TPT1 TPT2 207/30/58 220/29/57 544.669VRS
220/29/55.2 544.678 Total Station139/30/03 Interior
Angle
TPT2 TPT1 027/30/58TPT2 TPT3 198/49/59 188/40/59 957.778VRS
188/40/57.2 957.769 Total Station171/19/01 Interior
Angle
TPT3 TPT2 018/49/59TPT3 SURVEY 038/08/33 340/41/26 2165.470
VRS340/41/27.5 2165.441 Total
Station019/18/34 Interior
Angle
SURVEY TPT1 248/00/55 837.523 VRS837.500 Total Station
SURVEY TPT3 218/08/33 029/52/22Interior Angle
029/52/21.0
360/00/00 VRS359/59/59.1 Total Station
Ellipsoid Height Distortions of 3CM or Greater
Network vs OPUS
-0.020 -0.016 -0.004-0.032 -0.021 -0.011-0.015 -0.012 -0.003-0.022 -0.020 -0.002-0.013 -0.015 0.002-0.020 -0.017 -0.003-0.024 -0.015 -0.009-0.041 -0.015 -0.026-0.007 -0.008 0.001-0.011 -0.012 0.001-0.018 -0.012 -0.006-0.021 -0.018 -0.003-0.003 -0.012 0.009-0.048 -0.020 -0.028-0.044 -0.019 -0.025-0.028 -0.018 -0.010-0.024 -0.026 0.002-0.026 -0.025 -0.001-0.027 -0.024 -0.003-0.037 -0.023 -0.014-0.035 -0.024 -0.011-0.017 -0.023 0.006-0.022 -0.021 -0.001-0.049 -0.026 -0.023
-0.025 -0.019 -0.007-0.012 0.005 0.010
2 – 10 Minute Sessions Separated by 27 Hours
MeanStd Dev
Pub-Obs Pub-Pred Obs-Pred
Predicted values are weighted* means of the Network-OPUS Differences
*Weight Equals Ratio of Base StationSeparation Multiplied by Assumed Error
Network Integrity
24-Hour Coordinate Spread 1 cm N & E1.5 cm Ellipsoid Ht
Semi-Major Axis ~ 1 cm
Concluding Remarks
• Number of Registered Users• Maintenance Plan• Replacement Plan• Integrity Monitoring• Cost• Subscription Fee• Questions?