Custom Coordinate Transformation

To access the Transform Coordinates screen:

  • Data ribbon >> Transform >> Geographic.

  • Using the command line, enter "transform-coordinates"

  • Use the quick key combination "tco".

  • Display the Find Command screen, locate transform-coordinates and click Run.

Transform a spatial data file's coordinates from one system to another using your own conversion logic.

A transformation instruction is defined using one or more control point pairs, representing 3D coordinate positions in both a Source and Target world. Transformations can include as many control points as you need to define the 3D transition, and you can even pick control points in 3D using any available 3D window.

Once control points have been set, Calculate Transformation to determine the translation, scale and rotation parameters, which can be saved for later use.

Typically, transformations of this type are used to transform data between unknown and known coordinate references, where there are known destination points for data.

Note: you can also transform data between two standard coordinate systems, and can even automate the standard transformation function.

To set up a custom coordinate transformation:

  1. Define input and output files. See Transform Coordinates.

  2. Select the Custom tab.

  3. If relevant, load untransformed and reference data into a 3D window and display it, if this helps to define the target or destination coordinate spaces.

  4. In the Control Points table, define a control point representing a landmark for the untransformed source data. You can do this by either entering X, Y and Z coordinate values yourself, or using the pick button to choose a position in a 3D window.

    Tip: right click to snap to loaded data, or left click to select a position on the currently active 3D section.

    Defined points display in 3D. Source points are shown in green and, by default, with a numeric index. You can change the Label shown on screen by adding your own.

  5. Using the same approach, define a Target 3D point. Again, you can either set the position manually or pick 3D points.

    Target points display in red and carry the same Label as the Source.

    Note: at this point, a 2D transformation can be derived. Clicking Calculate Transformation at this point updates the Transformation table below to show the translation in X and Y (no scaling or rotation occurs).

  6. Add more control points if transformation in 3 dimensions is required.

  7. Click Calculate Transformation to update the table below.

  8. Review the Transformation table and adjust the transformation parameters if you need to:

    • Translation X/Y/Z—enter the translation distance in each major axis between Source and Target coordinate systems.

    • Scale Factor X/Y/Z—enter the exaggeration factor applied during transformation, along each axis. This factor essentially controls the modification of the data geometry to accommodate transformation between control points.

    • Axis 1/2/3—data may rotate during transformation. The Axis represents the major axis around which the Angle (degrees) rotation is applied (see below).

    • Angle—for each major axis, define the rotation applied during transformation.

  9. Save your transformation matrix as an external .xml file if you plan to share it with others, or other projects. Once saved, a transformation file can be Loaded to automatically transfer the settings to the Transformation group. This will also restore any control points that were saved.

    Note: you can also Restore previous settings made in a previous session.

  10. Click OK to transform your Input file based on custom transformation settings.

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