Geodetic | Global Positioning Systems (GPS)
Moderator(s): Burk Cornelius
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Oklahoma and Low Distortion Projections | 2022 0 B. Cornelius To improve the National Spatial Reference System (NSRS), NGS will replace the North American Datum of 1983 (NAD 83) and the North American Vertical Datum of 1988 (NAVD 88) with a new geometric reference frame and geopotential datum in 2022. The new reference frames will rely primarily on Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), as well as on a gravimetric geoid model resulting from our Gravity for the Redefinition of the American Vertical Datum (GRAV-D) Project. These new reference frames will be easier to access and to maintain than NAD 83 and NAVD 88, which rely on physical survey marks that deteriorate over time. As part of this project, NGS will fund and develop one zone for the entire state using the GRAV-D model that will be sufficient for most statewide GIS work. Through a concerted outreach effort by NGS, each state is being given the opportunity to choose how they would like to update their individual State Plane Coordinate systems. Staying with the old 2-zone system is NOT the most optimum solution for survey grade control work performed in Oklahoma. Instead our recommendation is to move forward with an LDP. Although there are several advantages to the LDP, one of the most obvious is the minimization of the grid-to-ground conversion factor. LDP’s will keep that factor to less than 0.1’ per mile in most cases. There is a lot more to an LDP than can be written in this short article. Please see page 12 of this issue for a more detailed paper on the science behind Low Distortion Projections and I think you will agree they are the way to go. NGS has requested that a preliminary LDP submittal from each state by December 2019 and the final design by December 2020. This doesn’t leave much time for us to decide what we want to do as a geospatial community. This is where the Oklahoma Society of Land Surveyors, Oklahoma Department of Transportation (ODOT), the State GIS Council and the State Board of Licensure for Professional Engineers and Land Surveyors come into play. In a collaborative effort we would like to propose that Oklahoma develop and adopt a system of Low Distortion Projections (LDP) instead of the current 2-zone State Plane Coordinate system. ODOT has already begun the process of requesting bids from qualified geodetic professionals to design an LDP system for Oklahoma. We want to be able to show NGS that geodetic professionals in our state all agree on the LDP model. As you probably remember, in 1990 with the coordination of Phil Stevenson and OSLS the State passed legislation adopting an official Coordinate System of Oklahoma. That system was based on a 2-Zone State Plane Coordinate System. When the new LDP system is adopted, this legislation will need to be amended accordingly. OSLS will dedicate its time and resources to accomplish this when the time comes Look for information on our Fall Conference to be held in Tulsa (probably in September) at which we will be discussing LDP at length. Any comments about the use of LDP’s or the use of one zone for the whole state can be sent to ODOT at OKLDP@odot.org or to OSLS at oslsl@osls.org
by B. Cornelius
Wednesday, May 29, 2019
Trimble R10 GPS Unit 2 M. Heilman @J. Ramsey, given the time frame, we are looking to have the LDP's set up utilizing the 2022 datum. And we will not implement the LDP's until the switch to 2022.
by K. King
Thursday, May 30, 2019
Western Data Systems - VRS Network 0 M. Ritchie I am looking to purchase an existing license/membership on the Western Data Systems - VRS Network.  Under Section 2.3 of your RTK Membership Agreement, you are allowed to sell them. If you are interested, please contact me: Mark Ritchie405-550-0168MarkAaronRitchie@live.com
by M. Ritchie
Thursday, September 11, 2014

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