Transition of the ORGN from NAD 83(CORS96) epoch to NAD 83(2011) epoch Ken Bays, PLS Lead Geodetic Surveyor Oregon DOT March 2013 ODOT Surveyors Conference

Overview   Review of our overall plan to transition the ORGN to NAD 83(2011) epoch   Changes ODOT made to GNSS Spider real-time network software   ORGN Real-time Products   ORGN Post Processing Products (RINEX)   Where to find the new and superseded ORGN coordinates   New ORGN Survey Mark Check-in web page

This is not a new datum! – –Reminder: Even though the new ORGN site coordinates are different, this is not a new datum.   It is a new realization of the NAD 83 datum   Same reference ellipsoid (GRS80) as all other realizations of NAD 83 – –Same origin – –Same orientation – –Same scale

NGS Guidelines for RTNs Oregon DOT goal for positioning the ORGN to align with the NSRS: - follow NGS Guidelines for RTNs: -

Oregon DOT’s written guidelines for positioning the ORGN closely follow the NGS guidelines.

Major Elements of ODOT’s Plan   Minimum of 10% of the stations in the ORGN will be NGS CORS   Process/Adjust with NGS OPUS Projects (beta) online   Process 5 days of data for all stations that were observed during high pressure period over the state   Fix NGS multi-year CORS sites in a least squares adjustment – –All fixed stations are NGS CORS sites that have “computed velocities” – –We did not fix NGS CORS sites in our adjustment that only had “modeled velocities”   Compare our adjustment results with other off-the-shelf least squares adjustment software: Trimble Business Center.

Major Elements of ODOT’s Plan   Compare our NAD 83(2011) epoch adjusted coordinates with other coordinate sources – –NGS CORS & NGS published OPUS-DB solutions, – –WSRN: Also officially transitioned to NAD 83(2011) epoch on 8 March   Note: The ODOT-adopted positions for stations in the ORGN may vary slightly from the NGS-adopted position of some of the stations that are also NGS CORS stations. This is because the NGS has acknowledged that regional real-time GPS networks such as the ORGN may require tighter internal consistency than the NGS policy provides for. The NGS draft “Guidelines for Real-Time GNSS Networks”, v.2.0, March 2011, state that "For the sake of internal network consistency, the RTN administrator may want to adopt his/her adjusted values for the CORS coordinates rather than use the NGS-adopted values.“NGS draft “Guidelines for Real-Time GNSS Networks”, v.2.0, March 2011 – –ORGN coordinates agree at the centimeter level with NGS and WSRN coordinates.

Major Elements of ODOT’s Plan   Seek NGS validation of our alignment of the ORGN to the NSRS – –Fiducial (trustworthy check-in) survey marks to ensure you’re your ORGN real-time correctors align with published survey mark positions.

ORGN Real-time Correctors after 8 March 2013 restart with ORGN referenced to NAD 83(2011) epoch   All ORGN RT Correctors are referenced to NAD 83(2011) epoch   We use NGS IGS08 absolute antenna calibrations in Spider.   We continue to send out our RT correctors reduced to the ellipsoid height at the Antenna Reference Point (ARP)

Rover Recommendations after 8 March 2013 ORGN restart with ORGN referenced to NAD 83(2011) epoch   Set the base receiver type as Unknown*   Set the base antenna as ADVNULLANTENNA, none, or null* – –* depending on manufacturer   Set the rover antenna to the IGS08 absolute antenna calibration for your particular rover. – –Work with your vendor/manufacturer to load IGS08 absolute calibrations. – –Be sure to include any vertical offset (in addition to the Phase Center Variation calibration) of your antenna ARP, i.e., the Leica height hook = 0.36 m.   Use GEOID12A in the rover if you need NAVD88 ortho heights in the field, i.e., stakeout. – –“GEOID12A is the only Geoid model that transforms between NAD 83(2011) epoch ellipsoid heights and the NAVD88 vertical datum ortho heights.” (NGS)

ORGN Post Processing Products (RINEX) after 8 March 2013 restart with ORGN referenced to NAD 83(2011) epoch   All RINEX files generated by the ODOT Spider Software and posted to the ORGN FTP site now have the new NAD 83(2011) epoch positions (lat, long, and ellipsoid height) embedded in the RINEX files header. – –Caution: RINEX files from our partner websites, may not always be referenced to NAD 83(2011) epoch   Always check with your RINEX file provider to see what datum realization their coordinates are referenced to.   Be sure you use the correct coordinates for each site, whether the superseded or new.   Be sure you don’t mix coordinate datum realizations on a project.

Post Processing after 8 March 2013 restart with ORGN referenced to NAD 83(2011) epoch   Geoid models for Post Processing: – –Use only GEOID12A in your post-processing software if you are processing your project in NAD 83(2011) epoch   “GEOID12A is the only Geoid model that transforms between NAD 83(2011) epoch ellipsoid heights and the NAVD vertical datum ortho heights.” NGS – –If you are processing your project in the superseded NAD 83(CORS96) epoch , you should use GEOID03 or GEOID09 in your post-processing software   NGS Antenna Calibration Page: – –Only (IGS08) Absolute Antenna Calibration values should be used when processing data with NAD 83(2011) epoch coordinates.

ORGN Coordinates Web Page   Link to the superseded NAD 83 (CORS 96) epoch coordinates   Link to the new NAD 83(2011) epoch coordinates for each ORGN site   Info about the ORGN transition – –Background on the transition – –ORGN real-time and RINEX product changes – –Transition plan – –Antenna Info – –Geoid Model Info – –Project Management Info   Link to new ORGN Check-In Survey Mark page   Link to Presentations from the 4 March 2013 webinar: “ORGN2011”

ORGN Check-In Survey Mark Web Page   Link to the new survey mark check-in form   Info about check-in survey marks   Benefits of check-in marks to ORGN users – –Validation that user is aligned to the NSRS   Info about benefits of publishing the position of a mark to OPUS-Database (OPUS Published Solutions)

Oregon Real-time GPS Network Ken Bays, PLS ODOT Lead Geodetic Surveyor Ron Singh, PLS ODOT Chief of Surveys, ODOT Randy Oberg, PLS ODOT Geodetic Surveyor Mark Armstrong, PLS NGS State Geodetic Advisor

  Back up slides

  Agricultural users in eastern Oregon are the least affected by the change to ORGN coordinates. Positions on the ground may only change 1 inch or so which may not require updating your land coordinate system. Agricultural users on the Oregon coast may or may not want to make changes depending how they use their GPS system. Updating your land coordinate system may be accomplished similarly to how surveyors will update their project coordinates in the next few slides. Agricultural Users

Surveying/Engineering Projects   Starting a new project in NAD 83(2011) epoch   Transitioning an existing NAD 83(CORS96) epoch to NAD 83(2011) epoch   Keeping an existing NAD 83(CORS96) epoch project in NAD 83(CORS96) epoch   Always document the datum realization of your project in your project meta data.   ODOT will issue policy procedures for ODOT projects to ODOT land surveyors and ODOT consultants.

Starting a New Project in NAD 83(2011) epoch   Post processing: – –Use the new NAD 83(2011) epoch coordinates for ORGN sites. ORGN coordinates are available at:   – –Use GEOID12A – –“GEOID12A is the only Geoid model that transforms between NAD 83(2011) epoch ellipsoid heights and the NAVD88 vertical datum ortho heights.” (NGS)   Rover using ORGN Real-time Correctors – –As always: Don’t use a transformation from WGS84 to NAD 83 in your rover because the ORGN RT correctors are already referenced to NAD 83.

Keeping a current project in NAD 83(CORS96) epoch   Perform a localization on your project after occupying your project control points with GPS while receiving ORGN RT correctors that are now referenced to NAD 83(2011) epoch   or alternatively :   Set up your own local RTK Base Station on your project using the superseded coordinates in your base and broadcast correctors to your rover in NAD 83(CORS96) epoch   Use the superseded ORGN coordinates and either GEOID03 or GEOID09 for post-processing your project.

Transitioning an existing NAD 83(CORS96) epoch project to NAD 83(2011) epoch   Perform a localization on our project to the new coordinate system.   or   Reprocess your static data: Do a new network adjustment fixing the new coordinates on your control stations.