Vertical Offset

A Vertical Offset transformation requires the creation of a Vertical Transformation with the type 'Vertical Offset', to convert between two different Vertical Coordinate Systems. There are a number of pre-defined objects in the Datasource, but it is also possible for users to define their own Vertical Offset transformations.

Object Definitions for Vertical Offset

Setting up object definitions for a Vertical Offset transformation from Vertical Coordinate System A (in linear unit C) to Vertical Coord Sys B (in linear unit D) requires the following:

  1. Ensure that Vertical Coordinate Systems "A" and "B" are in the Datasource.
  2. Create a new Vertical Transform "A to B" to represent the conversion from Vertical Coordinate System A to Vertical Coordinate System B. The Method should be "Vertical Offset."   
  3. The offset parameter should be set with the desired offset value and with units D.

Performing a Vertical Offset Transformation

To perform a Vertical Offset Transformation from Vertical Coordinate System A (in linear unit C) to Vertical Coordinate System B (in linear unit D) perform the following steps:

  1. Set up an interactive conversion with a Source horizontal Coordinate System (for example, WGS84) and Source vertical of "A". Set a Target horizontal Coordinate System (for example, WGS84) and Target vertical of "B."  
  2. Enter a height value (which should be in units "C") as part of the Source Coordinate Point Definition.  
  3. Clicking Calculate should prompt you to select a Vertical Transformation to convert from A to B, and should include "A to B" in the choices. If you select this transformation, the transformed point should have a  height value in units "D".

Vertical Offset and Slope Transformation

A Vertical Offset and Slope transformation requires the creation of a Vertical Transformation with the method 'Vertical Offset and Slope', to convert between two different Vertical Coordinate Systems. There are a number of pre-defined objects in the Datasource, but it is also possible for users to define their own Vertical Offset and Slope transformations.

Note on transformation parameters: The ordinate points are a test for the system provided by an issuing authority, and not used in the calculation. The Inclination in Latitude is the value (in radians) of the slope parameter in the latitude domain. The Inclination in Longitude is the value (in radians) of the slope parameter in the longitude domain. The semi-major and minor axis are the parameters used for the base ellipsoid.

Object Definitions for Vertical Offset and Slope

Setting object definitions for a Vertical Offset and Slope transformation from Vertical Coordinate System A (in linear unit C) to Vertical Coord Sys B (in linear unit D) requires the following:

  1. Ensure that Vertical Coordinate Systems "A" and "B" are in the Datasource.
  2. Create a new Vertical Transform "A to B" to represent the conversion from Vertical
  3. Coordinate System A to Vertical Coordinate System B. The Method should be "Vertical Offset and Slope."

The offset and slope parameters should be set with the desired offset value and with units D.

Performing a Vertical Offset and Slope Transformation

To perform a Vertical Offset Transformation from Vertical Coordinate System A (in linear unit C) to Vertical Coordinate System B (in linear unit D) perform the following steps:

  1. Set up an interactive conversion with a Source horizontal Coordinate System (for example, WGS84) and Source vertical of "A". Set a Target horizontal Coordinate System (for example, WGS84) and Target vertical of "B."
  2. Enter a height value (which should be in units "C") as part of the Source Coordinate Point Definition.
  3. Clicking Calculate should prompt you to select a Vertical Transformation to convert from A to B, and should include "A to B" in the choices. If you select this transformation, the transformed point should have a  height value in units "D.