A Helmert transformation, also known as a seven-parameter transformation, is a mathematical method used to convert coordinates between two different spatial reference systems. The transformation is based on seven parameters that describe translation, rotation, and scale differences between the two coordinate systems.
Note: For the fields described below, the values are defined as what is needed to get from Local Coordinates
- dX: Represents the Easting shift between the origins of the two coordinate systems.
- dY: Represents the Northing shift between the origins of the two coordinate systems.
- dZ: Represents the Elevation shift between the origins of the two coordinate systems.
- rot X: Represents the rotation around the x-axis of one coordinate system relative to the other.
- rot Y: Represents the rotation around the y-axis of one coordinate system relative to the other.
- rot Z: Represents the rotation around the z-axis of one coordinate system relative to the other.
- Scale (ppm): Represents the ratio of scale between the two coordinate systems.
These parameters are applied to the coordinates of points in one coordinate system to transform them into the corresponding coordinates in the other coordinate system.
They are particularly useful when working with datasets collected using different measurement techniques or coordinate systems, enabling accurate integration and analysis of spatial data.
- Calculate from Points: If three or more points have been specified for the localization, the pertinent Helmert parameters can be determined.
- Output to Text File: Opens the standard File Selector dialog box and allows you to save the Helmert parameters to an external file.