Datums and Tools to Connect Geospatial Data Accurately

Transcription

1 Datums and Tools to Connect Geospatial Data Accurately Pamela Fromhertz Colorado State Geodetic Advisor National Geodetic Survey National Oceanic and Atmospheric Administration GIS-T April 18, 2012 Loveland, CO

2 Agenda What is a Datum GPS - Accuracy NGS - National Spatial Reference System MetaData Tools DS-World CORS OPUS New Datums

3 Datums A mathematical and geometric concept that serves as a foundation or starting point for mapping, surveying, engineering based on realization of actual geospatial data points.

4 Geodetic Datums Horizontal 2-D (Latitude and Longitude) (e.g. NAD 27, NAD 83 (1986)) Vertical/Geopotential 1-D (Orthometric Height) (e.g. NGVD 29, NAVD 88, Local Tidal) Geometric 3-D (Latitude, Longitude and Ellipsoid Height) Fixed and Stable(?) - Coordinates seldom change (e.g. NAD 83 (1993), NAD 83 (2007)) also 4-D (Latitude, Longitude, Ellipsoid Height, Velocities) Coordinates change with time (e.g. NAD 83, ITRF00, ITRF05)

5 Standalone Positioning by 2017? 1-3 m

6 Standalone Positioning by 2017? cm??? C/A Code on L1 C/A Code on L2 New Code on L5 Better Resistance To Interference Faster Ambiguity Resolution GPS Modernization

7 Global Navigation Satellite System GPS GNSS Galileo GLONASS Beidou (Chinese) IRNSS (India)

8 GPS Receiver Grades Recreational Grade $100-$ meters Mapping $2,000-$6,000 submeter - 3 meter Survey Grade $10, mm 2 cm 2010 May 11 Federal Geospatial Summit 8

9 Autonomous GPS Accuracy 25 1 fix/15 sec = 6,000 fixes Mean Fix: 212 deg 50% of fixes w/in 1.8m 68% of fixes w/in 2.4m 95% of fixes w/in 4.2m 99% of fixes w/in 5.7m * 6.3 meters

10 Accuracy Precision

11 NGS National Spatial Reference System provides the Geospatial Infrastructure Critical to Our Economy Aviation Precision Agriculture Satellite Operations Trucking & Shipping Surveying & Mapping Power Grids TeleComm Oil Exploration Fishing & Boating Personal Navigation

12 The NSRS Evolves Positioning America in a dynamically changing world. Passive Control (Monuments) Active Control (CORS)

13 NGS National Spatial Reference System(NSRS) Improvements TIME NETWORK LOCAL NETWORK SPAN ACCURACY ACCURACY NAD meters (1 part in 100,000) NAD83(86) meter (1 part in 100,000) NAD83(199x)* meter B-order (1 part in 1 million) HARN A-order (1 part in 10 million) NAD83(NSRS2007) meter 0.01 meter (CORS) * CO was completed and adjusted in 2007

14 Source: Zurich-American Insurance Group Accurate positioning begins with accurate coordinates Geodetic control (the NSRS) is the foundation for all geospatial products. Without Geodetic Control as a base map layer, GIS applications will not work properly

15 Same point different datum's = different lat/long s COMET 1000 m radius 500 m radius Flagpole NAD83

16 Datum Differences NAD 27 NAD 83

17 Datum Difference NGVD 29 NAVD 88

18 Are NAD 83 & WGS 84 The Same? NO but for your application is it significant? If requirements are greater than 3m then Yes If requirements are less than 3m then No Federal Register Notice: Vol. 60, No. 157, August 15, 1995, pg Use of NAD 83/WGS 84 Datum Tag on Mapping Products

19 Tectonic Motions

20 State Plane Coordinates State plane coordinates are the projection of latitudes and longitudes (from the GRS80 ellipsoid) To a flat mapping surface that is usually defined by state law

21 Plane Coordinate Conversion Tools State Plane Coordinates GPPCGP (NAD 27 only) SPCS83 (NAD 83 only) UTM UTMS (Both NAD 27 & NAD 83) Both CORPSCON (Both NAD 27 & NAD 83)

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23 Height Modernization Height Modernization -faster -cheaper Differential Leveling (Orthometric HT) GNSS (Ellipsoid Ht)

24 Ellipsoid, Geoid, and Orthometric Heights H = Orthometric Height (leveling) h = Ellipsoidal Height (GPS) H = h - N N = Geoid Height (model) (NAVD88) H h (NAD83) TOPOGRAPHIC SURFACE Ellipsoid Geoid N Geoid Height (GEOID09) TRANSPORTATION = (-17.23*) METERS = *56.53 feet

25 Exaggerated view of the Earths Gravity Measure.

26 GRAV-D GRAV-D means fast, accurate, consistent orthometric heights everywhere in the USA GPS already gives fast accurate ellipsoid heights If the geoid were modeled (and monitored) to highest accuracy Voila Fast, accurate orthometric heights, anywhere, anytime No need to use leveling to bring in the datum Last Updated 13 Nov 2009 (DAS) 26

27 For instance: What is the Source of the Data? What is the Datum/Adjustment Epoch? What are the Field Conditions? What Equipment was used, especially what Antenna? What firmware was in the receiver and collector? What redundancy, if any, was used?

28 DSWorld Software Program Highly rated new NGS software tool Developed to search the NGS database Easy to learn/use Multiple search options available Displays search results using Google Earth

29 Geodetic Control Near the Budweiser Center Triangles Horizontal Control Blue First Order Squares Vertical Control Red Second Order

30 Triangles Horizontal Control Black - Third Order

31 Datasheets Photos Descriptions Recovery Directions

32 Direct Access to the NGS Datasheet

33 DSWorld opening screen

34 Where do you get DS-World?

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37 OPUS Online Positioning User Service OPUS S (2 hrs) OPUS RS (15 minutes) OPUS DB (Publish) OPUS Projects (Network)

38 4,000++ OPUS-Published Solutions April 2012

39 NGS Data Sheets Traditional blue booking New OPUS-DB

40 OPUS Submission Webpage Your address Location of your data file Your antenna type Antenna height Customize your solution - details on next slide

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44 CSRN GPS DAY CSRN- Colorado Spatial Reference Network (Chapter of the PLSC) MAY 12, 2012 Saturday 10:00 2:00 Utah Park Aurora, CO (1800 S. Peoria St) Free Food, Vendors, Boy and Girl Scouts

45 Introducing NAD 83(2011) epoch Multi-Year CORS Solution (MYCS) Reprocessed all CORS GPS data Jan 1994-Apr CORS & global stations NAD 83 computed by transformation from IGS08 National Adjustment of 2011 (NA2011) New adjustment of GNSS passive control GNSS vectors tied (and constrained) to CORS NAD 83(2011) epoch Approximately 80,000 stations and more than 400,000 GNSS vectors

46 Positions and Velocities Change! CORS Multiyear soln. Plate fixed

47 Changes in Horizontal NAD 83 Positions Different Epochs NAD 83(2011) epoch NAD 83(CORS96) epoch WA+OR 4.4E,5N cm ID+MT+ND+S D+WY 1.7E,0.5N cm East 1.4E, -0.2N cm CA+NV 10.8E, 14.4N cm UT+CO+N M+AZ 0.5E,1.0N cm

48 Changes in Horizontal NAD 83 Positions Same Epoch NAD 83(2011) epoch NAD 83(CORS96) epoch

49 National Geodetic Survey Ten-Year Plan Official NGS policy as of January 2008 Replace NAVD 88 with a GPS/geoid datum Replace NAD 83 with a geocentric GPS based datum

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52 Current/Future Activities of the NSRS 1. Multi-Year CORS solution National Adjustment (geometric) of passive control Hybrid Geoid Model using new ellipsoid heights New Data Sheets National Adjustment (vertical) of GPS passive marks Under consideration; This not adjusting the leveling network 6. Adoption of new datums

53 How to Plan for the Future Use most recent realization of NAD 83 Move away from passive marks to GNSS Move off of NGVD 29 to NAVD 88 Understand the accuracy of VERTCON in your area Collect OPUS-DB on NAVD 88 bench Require/provide complete metadata for all survey/mapping contracts How did they get the positions/heights? Survey Manual/Spatial Data Accuracy and Georeferencing Standards

54 Advisor Status In Your State

55 NGS Training Center Webinars!

56 More information NGS Home Page: geodesy.noaa.gov CORS Webpage: CORS newsletter OPUS Webpage: Find Your Advisor: This presentation will be uploaded to: FAQs on the various webpages

57 Questions GOOD COORDINATION BEGINS WITH GOOD COORDINATES GEOGRAPHY WITHOUT GEODESY IS A FELONY pamela.fromhertz@noaa.gov