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USING RT FOR ORTHO HEIGHTS

This article explores the use of real-time positioning technology for ortho heights, discussing the advantages, disadvantages, and new applications. It covers various methods and their accuracy levels, constraints, and guidelines for users. The article also mentions the use of GNSS for blunder checking and provides insights into how RTN ARP can be utilized for ortho heights. Additionally, it explores the improvements in 3D positioning with RTCM and the potential benefits for users.

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USING RT FOR ORTHO HEIGHTS

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  1. H88 = h83 – N03 HTMOD MEETING FEBRUARY 10, 2011 USING RT FOR ORTHO HEIGHTS Dr. Lew Lapine Bill Henning

  2. 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

  3. ≥200 RTN WORLDWIDE≥80 RTN USA≥37 DOT RTN IN THE USA (JAN 2010) • ACADEMIC/SCIENTIFIC • SPATIAL REFERENCE CENTERS • VARIOUS DOTS + MACHINE GUIDANCE • COUNTY • CITY • GEODETIC SURVEYS (NC, SC) • MANUFACTURERS • VENDOR NETWORKS • AGRICULTURE • MA & PA NETWORKS

  4. RT FOR ORTHO HEIGHTS • ADVANTAGES: • 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 STATIONSDISADVANTAGES: • LESS ACCURACY THAN LEVELING OR STATIC GNSS • REQUIRES ADEQUATE USER KNOWLEDGE OF ALL EFFECTS ON RT GNSS POSITIONING

  5. RT IN RELATION TO GOALS OF NHMP • 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

  6. 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)

  7. 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)

  8. CONSTRAINTS (OR NOT) • 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

  9. BLUNDER CHECKING POINTS WITH OPUS-RS

  10. NGS SINGLE BASE GUIDELINES • LEGACY EQUIPMENT • NO CELL COVERAGE • NEW RT CLOSEST BASE NETWORKS • MACHINE GUIDANCE AND PRECISION AGRICULTURE USE http://www.ngs.noaa.gov/PUBS_LIB/NGSRealTimeUserGuidelines.v1.1.pdf

  11. SINGLE BASE USER GUIDELINES- 95% CONFIDENCE

  12. 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

  13. 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.

  14. NTRIP & RTCM-IMPROVING 3D POSITIONING WITH NEW MESSAGES

  15. RTCM Paper 014-2007-SC104-462 Improving RTK with RTCM Network Residual Messages • Standard Solution (RMS:21 mm) • Optimized Solution (RMS:13 mm) • 2 Herbert Landau, Xiaoming Chen, Adrian Kipka, Ulrich Vollath - Trimble Terrasat GmbH Positioning improved by up to a factor of 2 Initialization time reduced by 30%

  16. RTN RESIDUAL RTCM 3.x MESSAGE TYPES https://ssl29.pair.com/dmarkle/puborder.php

  17. STATE SPACE RTCM 3.x MESSAGE TYPES

  18. EMERGING NGS ACTIVITIES…..

  19. 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 POSSIBLE METHODS OF RTN VALIDATION

  20. IDOP VALUES – 4 CORS EXAMPLE BEST 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 “IDOP” :THE SUBJECT OF A PAPER BY DRS. CHARLES SCHWARZ, TOM SOLER AND RICHARD SNAY .87 .87 .7 .6 .8 .5 .6 .7 .8 APPLICATION FOR RTN? .87 .87

  21. KNOW YOUR METADATA- UNIFYING THE VERTICALS TO A COMMON DATUM • 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

  22. SC – VRS Network To Support Surveying and Machine Control

  23. Presentation Overview • Introduction • VRS Network Design • Antenna Mounting Designs • Server Network Design • Modeling • Network Testing • Network Integrity • Practical Applications

  24. South Carolina Geodetic Survey Marine Transportation Highway Construction Infrastructure Mapping Obstruction Charting Surveying Engineering Utilities

  25. Motivating Force for a Network Application

  26. Antenna Hardware Tamper-Proof Leveling Head Stainless Steel Mount For Masonry Buildings Self Supporting 24 Foot Tower

  27. Server Network Design Should IT Be a Shareholder? 5 6 7

  28. Modeling Atmosphere - Tropo, Ion Clock Error - SV and Receiver SV Orbit Error Multipath Separation of Base and Rover The solution of Integer Ambiguity is influenced by external variables ??? Areal Variant Ionospheric Model 2 – 12hr Multipath Plots 1 cm I(λ,φ) = I0 +aλ∆λ + aφ∆φ -1 cm

  29. SC - VRS Network Design VRS Is Not Built In a Day! There Are Many Stakeholders!! They Are ALL Critical To Your Success

  30. Test Network 11 Counties, 6700 Sq Mi, 10 VRS Base Stations, 50 Control Pts

  31. VRS Absolute Accuracy Comparison 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* *(Local Accuracy2 + Eccentricty2 + System Design2)1/2

  32. Station SCBY Vertical Axis -0.010 to 0.014m

  33. Poor Choice for a Base Station! Vertical Axis -0.04 to 0.055m Diurnal E-W Motion of a 90 Foot Spun Concrete Tower

  34. Results From Test Of The SC RTN to Determine Accurate Ellipsoid Heights 95% Less Than 2.5 CM From Published Value -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 Centimeters Each Depicted Value Is A Mean Of Two 5-Minute Observations Spaced Approximately 21 or 27 Hours Apart

  35. Practical Applications

  36. Tidal Datum Transfer 2 mile transfer 0.05 ft uncertainty

  37. Classical Leveling vs VRS 1st Order Class 2 Leveling 4 Surveyors 4 days 5.5km – 6mm 1 Surveyor 4 hours 12mm comparison

  38. Comparison of VRS to Total StationRelative Accuracy Grid Brg Angle Rt Grd Dist TPT1 SURVEY 068/00/55 TPT1 TPT2 207/30/58 220/29/57 544.669 VRS 220/29/55.2 544.678 Total Station 139/30/03 Interior Angle TPT2 TPT1 027/30/58 TPT2 TPT3 198/49/59 188/40/59 957.778 VRS 188/40/57.2 957.769 Total Station 171/19/01 Interior Angle TPT3 TPT2 018/49/59 TPT3 SURVEY 038/08/33 340/41/26 2165.470 VRS 340/41/27.5 2165.441 Total Station 019/18/34 Interior Angle SURVEY TPT1 248/00/55 837.523 VRS 837.500 Total Station SURVEY TPT3 218/08/33 029/52/22 Interior Angle 029/52/21.0 360/00/00 VRS 359/59/59.1 Total Station

  39. Ellipsoid Height Distortions of 3CM or Greater

  40. Network vs OPUS Pub-Obs Pub-Pred Obs-Pred 2 – 10 Minute Sessions Separated by 27 Hours Predicted values are weighted* means of the Network-OPUS Differences *Weight Equals Ratio of Base Station Separation Multiplied by Assumed Error Mean Std Dev

  41. Network Integrity Semi-Major Axis ~ 1 cm 24-Hour Coordinate Spread 1 cm N & E 1.5 cm Ellipsoid Ht

  42. Concluding Remarks • Number of Registered Users • Maintenance Plan • Replacement Plan • Integrity Monitoring • Cost • Subscription Fee • Questions?

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