CORS Network > 1,865 Stations 226 federal, state, local and academic partners Growth > 231 new stations in 2012 Updated Guidelines CORS Obtain Static Data Files for CORS Here CORS Data Products Page Provide Information about your Project Enter your custom requests CDOT CORS/OPUS Team To incorporate CORS and OPUS into the CDOT Survey Manual Presented to SAC on Feb 15, 2012 Proposed Addendum Recommendations CDOT CORS/OPUS Team Addendum Online Positioning User Service (OPUS) Users submit GPS data to NGS Data is processed using NGS computers and software Resulting precise positionsed back to the user Solutions up to 1-2 cms in accuracy provided byOPUS Rapid Static - 15 minutes of data vs. 2-4 hours options: projects & publishing mark description your solution Online Positioning User Service OPUS geodesy.noaa.gov/OPUS / JGE 2011v1 IGS & NGS base stations & site information files IGS antenna calibrations & satellite orbits & reference frames UNAVCO teqc converter PAGES baseline processor var. geophysical models NGS geodetic toolkit IGS & NGS base stations & site information files IGS antenna calibrations & satellite orbits & reference frames UNAVCO teqc converter PAGES baseline processor var. geophysical models NGS geodetic toolkit your GPS data geodetic standard data OPUS OPUS S (2 hrs) OPUS RS (15 minutes) OPUS DB (Publish) OPUS Projects (Network) OPUS Submission Webpage Youraddress Location of your data file Your antenna type Antenna height Customize your solution - details on next slide New Look And Feel. The Options button accordions to a streamlined set of menus and entry fields. No more jumping to a new page. OPTIONS in/ Exclude CORS extended solution SPC zone geoid model project profile publish OPUS-RS or OPUS-Static (15 min-2 hr) (2-48 hr) >15 min of L1/L2 GPS data >>> geodesy.noaa.gov/OPUS/ Processed automatically on NGS computers, tied to CORS Solution via- in minutes Fast, easy, consistent access to NSRS Online Positioning User Service (OPUS) CORS solution #1 solution 3 solution 2 Static: OPUS determines your position with a differential GPS static solution, using hours of data. This process is repeated 4x from other CORS. solution 4 solution 5 your position: averaged from the best 3 of 5 CORS solutions h your peak-to-peaks: scaled from the spread of the 3 CORS solutions solution 2 = solution 3 = solution 5 = solution 4 = CORS solution #1 = Rapid-static: OPUS first creates an atmospheric delay model from surrounding CORS data. Your position is then quickly determined by differential GPS static solution. How is the Antenna Height Measured? ARP MARK The height is measured vertically (NOT the slant height) from the mark to the ARP of the antenna. The height is measured in meters. The ARP is almost always the center of the bottom-most, permanently attached, surface of the antenna. See GPS Antenna Calibration for photos and diagrams that show where the ARP is on most antennas:If the default height of is entered, OPUS will return the position of the ARP. Why Do I Need the Antenna Type? The antenna phase centers are located somewhere around here. The Antenna Reference Point (ARP) is almost always located in the center of the bottom surface of the antenna. The antenna offsets are the distance between the phase centers and the ARP You do not need to know these offsets. They are passed to the processing software through the antenna type Incorrect or missing antenna type big vertical errors ARP phase ctr. NGS Antenna Calibration Relative vs. Absolute GNSS Antenna Calibration relative absolute 2 hours GPS tracking OPUS Static vs. Rapid Static StaticRapid Static Input (dual-frequency GPS) 2-48 hours15 minutes-2 hours Output normal, extended, XML datasheet, project normal, extended, XML Accuracy (95%confidence) 1-2 cm horizontal 3-6 cm ellipsoidal height 1-2 cm horizontal 4-8 cm ellipsoidal height Network geometry 3 CORS, preferably within 1000 km of rover 3-9 CORS, surrounding & within 250 km of rover Availability global90% of CONUS (subject to CORS configuration) How Does OPUS-RS Work? OPUS-RS selects three to nine best CORS based upon: Having common satellite visibility with the user data. Having distances from the users site 250km Choi, 2010, personal communication. How Does OPUS-RS Work? In addition, users site must be no more than 50 km from the (convex) polygon created by the selected CORS. Again in this figure, the star represents the users site; the triangles are CORS. Five CORS and their resulting polygon are shown in this example. If the users site, the star, is more than 50 km outside this polygon, alternate CORS will be considered. If none can be found, the processing will abort. Schwarz et al., Accuracy assessment of the National Geodetic Survey's OPUS-RS utility, 2009, GPS Solutions, 13(2), OPUS-RS Coverage in Colorado How Good Can I Do With OPUS-S? More generally, Eckl et al. (NGS) preformed a similar but more extensive test using the same software but outside OPUS. Eckl et al., 2001, Accuracy of GPS-derived relative positions as a function of interstation distance and observing-session duration, J. of Geod. 75, ). Their results provide a good rule of thumb for accuracy versus session duration when using OPUS-S and in many other applications. 5,000++ OPUS-Published Solutions April 2012 OPUS-DB Published Solutions Why OPUS-DB A new easier way to capture data and have it in an NGS database Help populate Ellipsoidal Heights on Bench Marks, help with Geoid models and future vertical datums To the extent (?) they've bluebooked in the past, they can continue into the future more easily. If they are running RTK, this would help determine base station position and document where it was used, assuming they left a permanent mark. Changeover to new datums; either we maintain the data or user does for highest accuracy, but models will be available for bringing old coordinates forward. Marks Published. OPUS is showing steady growth in registered users and published marks. NGS Data Sheets Traditional blue booking New OPUS-DB OPUS DB Requirements Field Procedures GPS data file 4 hour durationdata file quality mark settingmark setting experienced observer fixed height tripod recommended brace tripod legs with sandbags or chain verify antenna height and plumbantenna height OPUS DB Requirements High-Quality OPUS Solution 70% observations used 70% ambiguities fixed 3 cm RMS 4 cm peak-to-peaks, lat. & lon. 8 cm peak-to-peak, el. hgt. properly identify antenna typeantenna type precise or rapid orbits (avail. next day) OPUS DB Requirements Mark Attributes photos of mark & equipment details (name, type, stability, etc.) description to aid mark recovery preview mark description form & help filemark description formhelp file OPUS-DB Requirements Issues to Consider Site instability, multi-path mark ID (search database, check stamping) Weather wild, local troposphere issues? space weather: ionospheric issues? Truth (orbits, CORS, etc.) Rapid (next-day) orbits required for publishing 2010 May 11Federal Geospatial Summit38 Interface The user is taken to a new page where they designate the mark associated with their data as new or recovered. 39 Interface - Existing mark designation After making that selection, the user is offered the appropriate form for entering the meta-data. Interface - New mark designation 2012 SurvCon Atlantic City NJ Review If the meta-data is complete, the quality control restrictions are met and the user gives the OK, the submission is entered into the data base after review by NGS. OPUS-DB Solutions 43 Interface 45 This is part of a published data sheet. Note the See Also highlight. Note the See Also highlight. This provides access to other data base and IDB entries for this mark. OPUS Datasheet Publishing Publishing Criteria: NGS-calibrated GPS antenna > 4 hour data span > 70% observations used > 70% fixed ambiguities < 0.04m H peak-to-peak < 0.08m V peak-to-peak Uses: GPS on BMs PLSS / GCDB Data archive Data sharing Orthometric Height Comparison m Published NAVD m OPUS GEOID m (0.18 ft) Difference OPUS-projects : first, run OPUS to harvest all project data OPUS automatically forms sessions from simultaneously observed marks, allowing multi-baseline processing and adjustment of multiple sessions. Whats happening now? Schenewerk is extending the PAGES suite to handle GLONASS and other GNSS. GLONASS PAGES will be able to process integer-fixed or float GPS and float GLONASS separately or together. The software is literally an extension of PAGES which has been proven in a variety of operational tasks. GNSS