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How-to Create a Geoid or VORF Model from a text file (v8.15 and older)

VORF – Vertical Offshore Reference Frame

A set of surfaces each of which defines the separation of one vertical datum from the WGS84 ellipsoid.

By combining surfaces, heights (depths) can be converted from one vertical datum to another.

Please follow the following steps to produce the VORF Model:

  1. Use QINSy version 8.10.2013.10.10.1 till 8.15
  2. Background about VORF
  3. You need to pay close attention from and to which vertical datum the VORF model is supplying corrections

  4. Open the VORF file in Excel and sort on Latitude
      • Check the difference between rows for Lat and Long and check if this is constant
      • Search for minimum Lat and Long and subtract half the spacing found above and you will have your VORF model origin which you need to use in a Geographical Grid as Grid Origin.

  5. Create a Riverline Model to check if the point spacing is constant:
    • How-to Create a Riverlines Model (v8.15 and older)
    • In some cases it is possible that the spacing is not constant as shown below:
      • In such case you need to filter your VORF file on the cell size and use only the smallest cell size available within the area you require to use.
      • You should create a file with constant point spacing and import that into a geographical grid within the processing manager.

  6. Please make sure to run QINSy as administrator:

    This is needed to allow QINSy to export the Geoid model to the program files folder as this is restricted due to Windows User Account Control (UAC) from Windows 8 onwards.

  7. Start the Processing Manager:
    1. Create Geographical Grid:
        • Enter the Cell size you determined with the steps above
        • Enter the User defined origin you determined with the steps above
        1. As there will only be 1 value per cell, only select the Mean attribute

    1. Import the text file into the Geographical Grid:
        • The Geographical Grid is not related to an ellipsoid, this means that it just contains a height without any reference.

    2. Import (GIS) the Riverline model into your project and overlay on the created Geographical Grid and check if the triangle corners coincidence with cell center of the created grid.

    3. Export the VORF Geographical Grid (Picture below needs to be updated):
        • Select the correct Ellipsoid

  8. Start Setup in the QINSy Console
    1. Change the geodetic settings in your Template Database:
    2. Check the transformation