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Geographic Coordinate Systems

A Geographic Coordinate System (GCS) defines the coordinate base of drawings within the MicroStation file. The appropriate GCS for a project can be determined by asking the Survey Section as it is determined by the setout of the survey control points. A new variable has been added for use in each project's .pcf file that sets the GCS for that project. Another line added to the project's .pcf file runs a macro that sets/resets the GCS of each dgn opened.

Update the .PCF file to include the GCS

Each project's PCF file can be found in the ...\NHDOT_Workspace\Projects\ directory. Open the PCF file with a text editor such as PFE or Notepad. Copy the following two lines into PCF file which will add the variable that sets the proper GCS and the command to run the setgeo macro which ensures that it is set properly when a dgn is opened.

GEO = 8329

The GEO variable defines which GCS to use of the four different alternatives available for State of NH projects. The first two digits of the GEO variable define the horizontal datum (either 83 or 11 for NAD83 or NAD83/2011) and the final two define the vertical datum (either 29 or 88 for NGVD 1929 or NAVD 1988). Change the "GEO =" to the appropriate number provided by the Survey Section.

NOTE: Remember to update any pcf file you may have copied into your personal workspace folder under ...\SSx-Workspace\Users\MX\ so your MX files get updated also.

Update GCS of all Drawings in the Project

Open any DGN file within the project to be modified. Set up a batch process to update all DGN files. Suggest turning on Workspace>Preferences>Operation>Automatically Save Design Changes before processing.

  1. Utilities > Batch Process...
    Batch Process Panel
  2. Use the option within the Batch Process dialog to add files or drag and drop from Windows File Explorer. It is easier to select all DGN files with File Explorer and drag them into the Batch Process dialog.
  3. Set the Initial Model dropdown to All Models. The program will process all models within the file once it is opened.
  4. Select all DGN files and click the Apply to Selection button.
  5. Save the batch process before proceeding.
  6. Click the magnifying glass to the right of the Command File box.
  7. Select ...\SS4-Workspace\Standards\data\macro-geo.txt, Click Open.
  8. Click Process Batch Process Job to process the files.

If the project's dgn file's units are in (international) Feet; a warning panel shown below may appear. Accept the default selection indicating that the elements are drawn correctly.

Checking the Drawing

The Geographic Coordinate System dialog is used to report, select or delete a GCS for the current model in a design file. Find this dialog from the MicroStation Tools menu, select Geographic > Select Geographic Coordinate System.

The Geographic Coordinate System dialog is shown below with the correct GCS attached and without:

geographic coordinate systems example

Geographic Coordinate System

This panel reports the Name, Description and Source of the current GCS. The GCS can be set from the Library, from a reference file, from a file or removed by selecting the last icon, Delete Geographic Coordinate System.

Setting the Coordinate System

From the Geographic Coordinate System dialog, select the From Library button (the second button from the left)
to get the Select Geographic Coordinate System panel.

geographic coordinate system

Geographic Coordinate System

At this point there are two choices, the Library option and the Search option. Each option is presented as tabs.
Of the two choices, the Search option is easier. Just click on the Search tab and enter the following Search Text
in the space provided; NH83. Click on the Find Now button to trigger the Search. Select the GCS with the "Key Name" of NH83/2011F from the search results. Click OK to apply this selection.

The following warning panel might appear.

geographic system warning message


Accept the default selection indicating that the elements are drawn correctly.

In order to set/check the vertical datum, use the Details tool (first icon) from the Geographic Coordinate System dialog box. A box containing the Geographic System Properties of the currently set GCS will appear. At the bottom is a section for Coordinate System Modifiers. Confirm that the Vertical Datum is correct or change if necessary. Click OK when finished.

New Hampshire Department of Transportation
PO Box 483  |  7 Hazen Drive  |  
Concord, NH  |  03302-0483
Tel: 603.271.3734  |  Fax: 603.271.3914