# To create a Helmert transformation

Local transformation support is available only when the Advanced Geodetic option is enabled in the Cogo settings screen of the job properties.

1. Tap and select Cogo / Adjust / Transformations.
2. Select Manage local transformations. Tap Next.
3. Select Create new transformation. Tap Next.
4. Set the Transformation type to Helmert and then enter the Transformation name.
5. Set the Scale factor type to one of the following:

- Free – The computed best fit scale factor is used in the transformation.
- Fixed– The scale factor you enter is used in the transformation.

6. Set the Vertical adjustment to one of the following:

- None – No vertical adjustment is carried out.
- Constant adjustment only – The average vertical correction computed from the elevations of the point pairs is used for vertical adjustment in the transformation.
- Inclined plane – A vertical correction plus a best fit correction plane is used for vertical adjustment in the transformation.

7. Tap Next.
8. Tap Add to select the Grid point name and Local grid point name pairs of points and then set the Use field to one of the following:

- Off – Do not use this point pair in the computation of the transformation parameters.
- Vertical only – Use this point pair only in the computation of the vertical adjustment parameters.
- Horizontal only – Use this point pair only in the computation of the horizontal adjustment parameters.
- Horizontal & vertical – Use this point pair in the computation of both the horizontal and the vertical adjustment parameters.

9. Tap Accept to add the pair to the list and then tap Add again to add more pairs of points.
10. To view the result of the transformation, tap Results.
11. Tap Store.

If you change the coordinates of a point used to define a Helmert transformation, you must recompute the Helmert transformation the new transformation to use the new coordinates.