How-to Create a Geoid or Vertical Offset Model (VOM)

This How-to describes step-by-step how to create your own geoid model file or height level correction model and use it within Qinsy.

See Questions & Answers for more in formation.
Also for items with an asterisk *.

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Questions & Answers

Subject	Question	Answer
Projected	What is projected data?	We assume that this is projected on project datum and the separation value is also relative to project datum.
Point spacing	What is regular and irregular spacing?	Irregularly spaced: Regularly spaced:
Point spacing	What is meant by having a different spacing in x and y?	The data can be regularly spaced but still have a different spacing in X and Y.
Area size	What is a small area?	This is a bit tricky since it mostly depends on points in an area: If you have an ASCII file that covers the whole continent or more, for example, it is recommended to use the BIN workflow. If it just covers your work site, using a QGFVOM is recommended. If the QGFVOM is larger than 15MB it is also a good indication that you might need to use either a smaller area or try the BIN workflow.
Datum	What is Project datum and Source datum?	Example of geodetic setup: Project datum: ED50 Source datum: WGS 84
Purple steps	What do they refer to?	How-to Create a Vertical Offset Model (QGFVOM) Workflow to create a QGFVOM model. How-to Create a Geoid model (.bin) before Qinsy 9.8.0 Workflow to create a BIN model. How-to Use the Geoid Model Migration Tool Use Geoid Model Migration tool to create a WKT for the BIN model.
Storage locations	Were are the different types of geoid model files stored?	See table below for more info.
QGFVOM VS BIN	What is the advantage of one format over the other?	See table below for more info.

More info on storage locations

Source

Type

Format

File location

Additional info

QPS Installers

Geoid Models

bin

C:\Program Files (x86)\Common Files\QPS\GeodeticResources\Geoid

Before Qinsy 9.6.0:
C:\Program Files (x86)\Common Files\QPS\Geo\Geoid

All (pre-defined) Geoid BIN files installed by Qinsy using the separate Geodetic resources installer: Release Notes

Created by user

Geoid models

bin

C:\Users\Public\Public Documents\QPS\Shared\Geo\Geoid

Geoid BIN files (Lat/Long and E/N), created from a Sounding Grid exported as Geoid Model

Vertical Offset Models

qgfvom

Project folder\Geoid

Vertical Offset Models (VOM) in *.qgfvom format as created in the Survey Manager.

Previously: River Line Model and VORF models in PRO format.

More info on QGFVOM VS BIN

	QGFVOM	BIN
Used in all QPS software
Use for large areas
Irregularly spaced points
Regularly spaced points
Datum (ellipsoid) aware