City of Gresham Oregon
Gresham Control Points
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About

Welcome to the City of Gresham’s Control Points GIS map. The City has developed a network of horizontal and vertical control monuments throughout the city to support surveying, engineering, construction, mapping, GIS and facilities management activities.

Engineers, surveyors, planners and other consultants working on public improvements are required to georeference their work to the City's vertical and horizontal datum.

  • The horizontal datum is Oregon State Plane Coordinates, North Zone, being NAD83(91), in International Feet.
  • The vertical datum is NGVD29, in US Survey Feet.

This web application displays the main control point’s location and its spatial information.

Gresham Control Points

Each control point is typically a standard City of Gresham 2-inch bronze disk monument with a raised datum point (Berntsen Model CD2LB), stamped "City of Gresham Control Do Not Disturb".

  • Each control point was occupied for a minimum of one hour, on each of two different days.
  • The values established on the points were constrained to a minimum of three City of Gresham primary control points.

Specifications:

  • NGVD29 US Survey Feet
  • TOPCON HIPER+ GPS receivers
  • Static L1 L2 Vector reduction performed by TOPCON Tools Software (version 8)
  • Least Squares adjustment performed by STAR*NET Software (version 7.1)

Disclaimer

The City of Gresham provides no warranty, expressed or implied, as to errors, omissions, suitability of purpose or positional accuracy, of City control points. Use of these control points requires due diligence, by the professionals using the information, to ensure the accuracy and appropriate use of the control.

The monuments shown here have superseded all previous City of Gresham control points. The legacy control points have been purported to be on the same datum but present considerable variation in origin, type, permanence and methodology. The new network has consistency in type, location and methodology.

Links

Gresham GIS Home GreshamMap: Interactive GIS Map