Add, edit or view a coordinate transformation.
Manage / Configuration / Coordinate Systems / Transformations / 
or 
- Transform module
| General | Description |
|---|---|
| Name | Type a name for the transformation. |
| Reverse Name | Type a name for the reverse transformation. |
| From Coordinate System | Select the coordinate system the transformation transforms coordinates from. |
| To Coordinate System | Select the coordinate system the transformation transforms coordinates to. |
| Coordinate Type |
ECEF - Coordinates to transform are Earth-Centred, Earth-Fixed Cartesian coordinates (i.e. X, Y, Z). Grid - Coordinates to transform are projected map grid coordinates (i.e. Easting, Northing, Height). |
| Transformation Type | Select type of transformation. See Transformation Types table below. |
| Units | Description |
| Linear | Select the units for linear transformation parameters. |
| Angular | Select the units for angular transformation parameters. |
| Parameters | Description |
| Scale | Type the scale factor for the transformation. |
| X Scale | Type the scale factor for the X axis. |
| Y Scale | Type the scale factor for the Y axis. |
| X Shift | Type the translation distance along the X axis. |
| Y Shift | Enter the translation distance along the Y axis. |
| Z Shift | Type the translation distance along the Z axis. |
| X Centre | Type the centroid X coordinate. |
| Y Centre | Type the centroid Y coordinate. |
| Z Centre | Type the centroid Z coordinate. |
| Rotation | Type the rotation angle of the axes. |
| Rotation Order | Select the order in which the axes rotations will be applied. |
| X Rotation | Type the rotation angle about the X axis. |
| Y Rotation | Type the rotation angle about the Y axis. |
| Z Rotation | Type the rotation angle about the Z axis. |
| Skew | Type the angular skew of the axes. |
| Grid File | Select the file that contains the grid based transformation. |
| Preserve Orthometric Heights | Select if orthometric heights should be preserved when applying the transformation. |
The Units and Parameters displayed will vary depending upon the Transformation Type selected.
Transformation Types
| ECEF | Description |
|---|---|
| Bursa-Wolf | A conformal three dimensional Cartesian coordinate transformation. Also known as a similarity or seven-parameter transformation. |
| Molodensky-Badekas | Similar to Bursa-Wolf except the coordinates of both systems are first shifted into a common origin via centroidal coordinates. |
| Grid | Description |
| Helmert | A two dimensional conformal transformation that applies a scale, a rotation and X & Y translations. |
| Semi-Affine | Compensates for differences in scale along the X and Y axes. Typically used to remove any stretch or shrinkage along the X and Y axes. |
| Affine | Similar to Semi-Affine except it also compensate for any difference in orthogonality. |
| Grid File (NTv2) | National Transformation version 2 (NTv2) is a standard binary grid shift format that consists of a single file with a .GSB extension. |
| Grid File (NADCON) | North American Datum Conversion (NADCON) is a standard binary grid shift format that consists of two files, one each for latitude and longitude shifts, with .LAS and .LOS extensions respectively. |
- From Coordinate System and To Coordinate System lists are populated from the coordinate system available in the project.
- If the Coordinate Type is set to ECEF then WGS84 and ETRS89 coordinate systems are also available. This enables transformations to be created that can be used when importing from or exporting to systems that do not have projected grid coordinates.
- Grid File transformations consist of a grid of shift values from which translations between the two coordinate systems can be interpolated. This type of transformation is generally considered to be the most accurate because it can compensate for any distortions between the two systems.
