GIS Website Main Menu

Geodetic Control

Geodetic Control supports accurate horizontal and vertical placement of all other layers, particularly Cadastral (by improving horizontal locations), Hypsography (by providing accurate elevations from Height Modernization), Land Cover, Orthoimagery, Soils and Wetlands from a combined campaign to acquire LIDAR data or other Remote Sensing data collected with accurate positions and elevations provided by Height Modernization.

Goals for Geodetic Control are to work with other theme efforts to provide accurate and accepted control data for Montana. Goals include improving GCDB accuracy enhancement in priority areas, advancing the Height Modernization program in Montana, promoting public access to public control data including GDCB, promoting the use of standards for reporting control data, developing an on-line database for storing, querying & accessing control data, potentially promoting legislation to require that control generated with public funds be submitted to the public database, promoting training and education opportunities to foster an understanding of the value and use of control.

Goals & Objectives

Theme goals for the next two years include:

  • An expanded educational effort promoting the value of geodetic control and the use of the Montana Control Point Database.
  • Integration of geodetic control as a reference layer in GIS databases.
  • Work with the boundary cadastral theme champions to insure non-duplication of efforts.

Status of Framework

Most objects depend on having an on-line database for control. The State of Montana is most of the way through the development of a functional database. The database is expected to come online mid-summer of 2006. Data may then be entered into the system by surveyors And the public may access the control point data.

Some education and outreach has occurred, on a limited basis. The responses have been positive regarding the willingness to contribute control point data.

Major issues:


  • Complete the programming and install the database. This issue is in the hands of the software developer, who is expected to complete phase one of this application in the summer of 2007.
  • Informing the land surveying community that the database is available and encourage the surveyors to submit their data. Once the database is up and running, the existing grant funds from the BLM may be used to fund workshops and outreach around the state to inform and train the survey community. An article and perhaps advertising may be placed in the Montana Association of Land Surveyors trade journal. A presentation may be schedule for the MARLS conference in February- this can be done annually, or perhaps a booth can be shared with the US Geodetic Survey at the MARLS conference.
  • Informing the public that the database is available and should be referred to prior to scoping out any GIS, surveying, engineering and aerial photography project in order to research the availability of control in their project area. Conference presentations may be scheduled, and an article may be submitted to the MAGIP newsletter. A presentation may be schedule for the Northern Rockies GIS conference in April. Perhaps a booth may be shared with the US Geodetic Survey at the Northern Rockies GIS conference.
  • Long term funding to maintain the viability of the database (server hosting, software upgrades, database management). Not addressed at this time.
  • Tying this database to scanned corner records. Not addressed at this time, but dialog has begun on this.

2006 – 2008 Stewardship Plan


A strategic plan to densify control requires, as a first step, the creation of a Geodetic Control Database that documents existing control and serves as a tool to help identify areas in need of densification. An accumulation of the existing Geodetic Control in one single accessible database would likely result in literally thousand of points and may adequately cover the developed portions of Montana. Therefore, it seems prudent that before Montana develops and undertakes a project specifically aimed at densifying geodetic control, an initial effort be aimed at inventorying existing control. Initial efforts to populate a Geodetic Control Database should focus not only on the addition of newly created points, but perhaps more importantly, importation of existing control. Specific tasks for the 2006 - 2008 time frame include:

  • Complete the installation and testing of the Surveying and Mapping Control database (MONTANA CONTROL POINT DATABASE) developed under the direction of the Geodetic Control Implementation Team using funds from the assistance agreement in place between BLM and ITSD. Installation of version one of this database is to take place the week of July 10, 2006 on ITSD servers.
  • Contract with a licensed land surveyor or licensed land surveying firm to administer the control database.
  • Educate the surveying community as to the existence and use of this database.
  • Populate the database.
  • Develop a control densification plan for Montana.
  • Develop state standards for control data submission and dissemination.
  • Test the feasibility of linking scanned corner recordation records to the database.
  • Work with MDT and NGS to develop a Height Modernization program.

History of Framework

Efforts to elevate the awareness of geodetic control and coordinate geodetic control information across Montana began in the late 1990s with a core group of surveying and GIS representatives. This group has representatives from the Montana Department of Administration, Montana Department of Transportation, US Bureau of Land Management, US Forest Service, local government, the private sector. Since developing the strategic plan for Montana’s geodetic control this working group meets intermittently, typically via conference call, and communicates via email. Many of the members of the geodetic control working group are also on the executive committee for the Montana Height Modernization Program

Stewardship Contact Information

Theme Steward

Department of Administration, ITSD
GIS Bureau
101 North Rodney St, STE 2
Helena, MT 59620-0113

Geodetic Control Framework
Theme Lead

Rj Zimmer, PLS
DJ & A, PC
302 N Last Chance Gulch
Helena, MT 59601
Fax: 406-443-8176
Phone: 406-443-0962
E-mail: RjZimmer@djanda.com

Stu Kirkpatrick
Department of Administration, ITSD
GIS Bureau
101 North Rodney St, STE 2
Helena, MT 59620-0115
Fax: 406-444-1255
Phone: 406-444-9013
E-mail: skirkpatrick@mt.gov

Theme Lead's Corner

February 16, 2007

Geodetic control is like the nails that hold a house together. It is the fundamental framework layer that serves as the spatial reference for the alignment of all GIS and mapping features. Without geodetic control as a way to relate mapping to a common spatial reference, there would be no way to align the various GIS layers in a cohesive and consistent manner.

Geodetic control is the physical representation of the projections and coordinate systems used in mapping and geodesy, and thereby, provides a way to know and communicate where something is within coordinate space. The nation's foundation for positioning is expresed in the National Spatial Reference System.

We get our National Spatial Reference System (NSRS) from the National Geodetic Survey (NGS), which evolved from the Survey of the Coast. The Survey of the Coast was our nation's first civilian scientific agency, when it was formed in 1807 by President Thomas Jefferson. Over the years the mission of this agency grew to include surveying the interior lands under the name US Coast and Geodetic Survey. The NGS is now celebrating its 200th anniversary.

The National Geodetic Survey (www.ngs.noaa.gov) is the federal agency that is charged with defining the geodetic coordinate values for the various survey marks that it historically laid out across the continent. Although the NGS no longer performs field surveys, it does update coordinate values of the existing markers as scientific advances improve our ability to measure and refine location and position.

In addition to the control that was established and tracked by the NGS, there are control points established by other public and private surveyors. Other federal agencies such as the Bureau of Land Management, the Bureau of Reclamation, the US Forest Service, the US Army Corps of Engineers, state agencies, local governments, and private companies create control for project specific purposes. The NGS estimates that their database contains only 1% of the existing geodetic control in the nation. Here in Montana, as in some other states, we try to capture some of that missing 98% in a statewide database - the Montana Control Point Database.

~ Rj Zimmer, PLS

Photo Courtesy of Rj Zimmer, PLS