How-to Create a Vertical Offset Model (v8.18.2 and up)

This How-to is applicable to QINSy versions 8.18 and up. The How-to's for previous versions can be found here:

This How-to describes how you can create a Vertical Offset Model using the Processing Manager and how to select it for online use.

Within our software you can create 2 kinds of files:

  • *.QGFVOM
  • *.BIN

Advantages


QGFVOMBIN
Used in all QPS software(error)(tick)
Irregular spaced points(tick)(error)
Regular spaced points(tick)(tick)

Storage locations


File LocationFormatGeoid typeSource
QINSy 8.16 and newerC:\Program Files (x86)\Common Files\QPS\Geo\GeoidBINAll (pre-defined) Geoid BIN files installed by QINSy using the separate Geoid_2.0 installerQPS installers
C:\Users\Public\Public Documents\QPS\Shared\Geo\GeoidBINGeoid BIN files (Lat/Long and E/N), created from a Sounding Grid exported as Geoid ModelCreated by user
Project folder\GeoidQGFVOM

Vertical Offset Models (VOM) in qgfvom format as created in the Processing Manager

Previously: River Line and VORF models in PRO format

Created by user
Common Files Folder\Geoid
Old versionsC:\Program Files (x86)\QPS\QINSy\GeoidBIN

No files will be installed by QINSy anymore,

Could contain previously installed or created files

QPS installers

VOM Heights are applied after Projection

Please note that when a Vertical Offset Model is used as a Vertical Datum, the heights will be applied after projection.

Method 1 - Importing ASCII points into Vertical Models file (QGFVOM)  "Riverlines Model"

  1. In the Project Explorer tree - Vertical Models: click with right mouse button
  2. Click New


  3. The New VOM Wizard will be started

    Use the browse button [ ... ] to select the file containing the separation data.

  4. A regular Windows search window opens.
    Select the file type you wish to import.
    The most likely import is an ASCII points file, which we will work with in this example, but other import files are supported as well.

    Select the file to use and press 'Open'

  5. Either select one of the standard layouts of the to-be imported file using the drop down menu,

    or use the browse button [ ... ] to open the Layout Editor where manual options can be entered.
    Either continue with step 6, below, or continue to step 7.

  6. This dialog can be used to indicate the specific layout of the file to be imported

    Paste a line of your file in the 'Example' field and press 'Test'.
    The data as it will be stored in the VOM file will be shown in the 'Output' field.

  7. Ingnore the following dialog for now. There is a known issue that still needs to be fixed.
    Note that the imported data should always be relative to the Local Survey Datum.


  8. Only when a boundary file is available the 'Use a boundary' option needs to be activated

    Press 'Next' to continue to the next page of the wizard, press the arrow button at top left to return to the previous page.

  9. Leave this option activated so no unnecessary triangles are created in the DTM.

    The Link angle and Link distance are set in the Processing Manager's - Ribbon Tab File - Options - Link Settings menu but can be overruled here.

  10. Type in a name for a new file or use the browse button [ ... ] to select an existing file.

    Choose a color map to show the height variations in the offset model.
    Height accuracy: this value represents how accurately the height difference was determined.

  11. This page shows all the settings as entered in the previous wizard pages.

    Press 'Start'

  12. The VOM has now been created

    Press 'Save output' if you would like a log file record of the process.
    Press 'Finish' to close the wizard.

  13. The new qgfvom file is listed in the Project Explorer window under Vertical models.
    A GEOID AREA and GEOIDPOINTS layer are automatically created. 


  14. The layer GEOIDAREA contains the outline of the imported points.
    The layer GEOIDPOINTS contains the VOM in color.

  15. The model is visible in the Plan View.
    If it doesn't display right away, then right mouse click on the GEOIDPOINTS layer and select 'Zoom to fit'.


  16. To check whether the links between the points are to your satisfaction, the grid can be switched off:
    - Select the vertical model in the Project Explorer tree
    - Right click on it
    - From the menu select 'Color scale settings'
    - For Color map select <No color map>
  17. The DTM links are now shown

    Use the right mouse menu again to return to the color scale used earlier.

  18. The model is stored in the Geoid folder of the project or support project.

    Surveypoints, Geoidpoints

    The Vertical Offset Model is like a 3D model which can be checked by drawing Quick Profiles in the 2D Plan View.

  19. In Database Setup - Datums, under Mean Water level Model, select 'Geoid Height - River Lines'.
    There you can select the Vertical Offset Model as created in the Processing Manager.


    Surveypoints, Geoidpoints

    The Vertical Offset Model is like a 3D Design model and can be imported into a Sounding Grid to check if the model does not contain strange features. The best method to do this is currently under investigation.
    From there it can be exported as a geoid model separation grid, which creates an XML file and a BIN file, stored in the Public Shared files. This makes it available for other projects as well.
    See tab 'Use in QPS software'.

Method 2 - Importing a file into a Sounding Grid (and then exporting a BIN file)

Datum imported data

Your imported data has to be on one of the following ellipsoids:

  • WGS '84
  • GRS '80
  • ETRS '89
  • NAD '83
  • ITRF

  1. Create a new Sounding grid
    1. In the Project Explorer tree - Sounding Grids: click with right mouse button
    2. Click New



  2. Set up the Sounding Grid

    1. Select an appropriate bin size
      1. If you cannot enter enough decimals, change your global settings in the Console
    2. Set Origin mode to UserDefined
    3. Grid units: Geographical seconds:

      Open the 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 model origin which you need to use in a Geographical Grid as Grid Origin.


  3. In the Project Explorer tree, select this newly created sounding grid, then right mouse click, Import, Fill method Points file.
    In the Import settings pane, add the ASCII points file to import and click on the browse button [ ... ] next to File format, this brings up the Layout Editor.


  4. In Layout Editor, select the layout to correctly import the ASCII file.

    Use the Test button to check if the data string is decoded, click OK and click Fill to import the points.

  5. You can QC the sounding grid by adjusting the Color settings.


  6. Select the grid and press 'Export' to export the separation grid to File type 'Geoid Model' to be able to use it in Database Setup.
    Selecting as 'Output folder': Geoid.


  7. Pressing 'Export' creates an *.xml and a *.bin file.
    Saving these files in the Public folder will make them available for other projects as well.
    They need to be stored in the Geoid folder to be available as a Vertical Offset Model in Database Setup.

    Surveypoints, Geoidpoints

    The Vertical Offset Model is like a 3D model which can be checked by drawing Quick Profiles in the 2D Plan View.

  8. You can now select the separation geoid (grid) in Database Setup

Method 3 - Creating QGFVOM from Scratch


    • 1. Press the File icon

    • 2. Select New

    • 3. Press Line File



  1. Open an existing file or enter a name for a new file in which to store the points:

    Save as a Geoid / Vertical model (*.qgfvom) in the Geoid folder of the active project.

  2. The new model file is listed in the Project Explorer window under the Vertical models.
    A GEOIDPOINTS layer is automatically created. This name may be changed and additional layers can be generated.
    When the *.qgfvom is selected in the Project Explorer tree, the Line tools become active:


  3. Select the layer on which to store the lines and points or create a new layer first, using the 'Edit layers' button.


  4. Press 'Create object', left-clicking in the Plan View and right-clicking to finish the line and to open the Add New Object window.

    Enter a name and press OK.

  5. Use 'Edit objects' to check on the created points, adding heights as necessary - lines are not used in the model, points are.


  6. Press 'DTM link' and select the Output layer.

    If needed the link settings can be changed, the defaults are 160 degrees and 100 meters.
    Press 'OK'.

  7. This will start the creation of triangles between the points. The triangle links / legs between the points will now be visible.


    Press 'Undo' if links are not to your satisfaction and press 'DTM Link' again to enter different settings.


  8. Press 'Export' and select 'Vertical Offset model':


  9. Select which layer to export, set the accuracy and enter a file name, here: ETRS-UTM-VORF.qgfvom

    Press 'OK'.

  10. Right-click on the vertical model and select 'Open containing folder' to check that your DTM model is in the right location:


    It needs to be stored in the Geoid folder of the project or support project you are using to be available as a Vertical Offset Model in Database Setup:



    Surveypoints, Geoidpoints

    The Vertical Offset Model is like a 3D Design model and can be imported into a Sounding Grid (ENH) to check if the model does not contain strange features. The best method to do this is currently under investigation.
    From there it can be exported as a geoid model separation grid, which creates an XML file and a BIN file, stored in the Public Shared files. This makes it available for other projects as well.
    See tab 'Use in QPS software'.


    Surveypoints, Geoidpoints

    The Vertical Offset Model is like a 3D model which can be checked by drawing Quick Profiles in the 2D Plan View.


How to apply the newly created model in Database Setup

When editing the Mean Water Level Model and/or the Vertical Datum / Chart Datum on the Geodetic Parameters pages,
select either

  1. The 'Geoid Height - River Lines' option
    • If the geoid separation points are absolute heights on the selected survey datum.
      Browse for the qgfvom

  2. The 'Height Level - River Lines' option
    • If the geoid separation points are relative heights with respect to another geoid model.
      Browse for the gqfvom.