GPS and Geodetic News You Can UseGPS and Geodetic News You Can Use

David Conner

Geodetic Advisor to the State of Ohio

National Geodetic Survey, NOAA

2008 Ohio GIS Conference

September 10-12, 2008

Crowne Plaza North Hotel

Columbus, Ohio

TOPICS

• Overview• National Readjustment - NAD83 (NSRS2007)• GPS CORS, OPUS, OPUS-DB, and more • County Scorecard

Shifts in Ohio

NAD 83 (1995) vs NAD 83 (NSRS2007)Horz Shift Average : 0.016 m (Max: 0.348 m) Vert Shift Average : 0.013 m (Max: 0.503 m)

Example actual horizontal shifts at station SMITH (JY0742)

NAD 27 vs NAD 83 (1986) ~ 13 metersNAD 83 (1986) vs NAD 83 (1995) ~ 20 cm NAD 83 (1995) vs NAD 83 (NSRS2007) ~ 1.5 cm

For Stations not IncludedIn the NSRS (2007) readjustment

• NGS recommends that NAD 83 data that is not part of the NSRS readjustment be readjusted using original observation data

• Because of the relatively small shifts involved transformation software such as NADCON will not be developed for NAD 83(NSRS2007)

• NADCON accuracy ~ 6 cm (0.2 ft)• NAD 83 (NSRS2007) avg shift ~ 2.5 cm

• NGS will streamline the process of project acceptance

• OPUS DB – coming soon - ?

Ohio’s GPS CORS NetworkBrought to you courtesy of the ODOT,

Bureau of Aerial Engineering

VRS/ CORS information

Telephone: 614-275-1372, or

614-351-2839.

cors@dot.state.oh.us

CORS/OPUS: Overview & Status

The CORS network contains about 1,250 GPS tracking stations, and it is growing by about 200 stations per year.

OPUS is a Web-based service enabling users to automatically post-process GPS data.

CORS = Continuously Operating Reference Station

Vertical standard error achievable when a user submits 15 minutes of GPS data to OPUS-RS

OPUS FLAVORS

Try it …

http://beta.ngs.noaa.gov/CORS-

Proxy/oraOpusDbWeb/

OPUS-DB

OPUS-DB

Sample Datasheet

OPUS Datasheet Concept

GPS data requirements

“OPUSable” 4+ hours of dual frequency data NGS-calibrated antenna OPUS must achieve:

≥ 70% observations used ≥ 70% ambiguities fixed ≤ 0.04m peak-to-peak horizontal ≤ 0.08m peak-to-peak vertical ≤ 0.03m RMS

NGS-modeled antenna

NGS-modeled antenna

GPS data (4+hr, good stats)

*optional for “existing” stations.

control station description *

control stationphoto *

metadata requirements

observationnotes

Simplified bluebooking

antenna type, height

• NOAA has a relatively new performance metric that assesses how well we are doing at “enabling” local capacity for accurate positioning. This metric: Makes use of NOAA’s Online Positioning User Service (OPUS) as a proxy to

assess the local use of NOAA positioning tools and services. Was developed over the past several years in partnership with National Association of County Surveyors (NACS).

Involves the use of a web-based county scorecard of 23 survey questions specifically focusing on infrastructure, NGS models and tools, NGS capacity building and outreach, and overall satisfaction.

• We need input from YOU, our core customers, to help NOAA improve its geospatial products and services.

• For more information, visit http://www.ngs.noaa.gov/scorecard/or contact: Your NOAA State Geodetic Advisor, in Ohio Dave.Conner@noaa.gov

(for current list of all Advisors visit http://www.ngs.noaa.gov/ADVISORS/)OR Brett Howe (Brett.Howe@noaa.gov)

We want YOU

to tell us how we’re

doing

NOAA’S County Scorecard

Our Performance Metric Asks• Are Counties using NOAA’s positioning products and services?

NOAA looks at County Online Positioning User Service (OPUS) use as a proxy. Have there been 25 or more OPUS solution generations in a given county in the last 12 months?

Counties meeting the above criteria are “substantially enabled” (shaded yellow).

• Is there feedback and interaction between the local community and NOAA?

Is the County in a State that participates in the NOAA State Advisor/Coordinator program?

Has a County Geospatial Representative been identified (eg County Surveyor, County Engineer, GIS Administrator, or equivalent)?

Has “blue book” data from the County been submitted to NGS through activities such as: leveling project software, GPS projects and OPUS DB (when available)?

Has a County Scorecard web survey been filled out by the County Geospatial Representative?

Counties meeting the above criteria are “fully enabled” (shaded green).

County Scorecard Details

NOAA’S County ScorecardHow you can help …