To Define a Geodetic Transformation Path

To define a geodetic transformation path

1. Click Map Setup tabCoordinate System panel Create Create Geodetic Transformation Path.
2. In the Geodetic Transformation Path Definition wizard, Create A Geodetic Transformation Path is selected. Click Next.
3. specify whether to create a geodetic transformation path from scratch, or modify an existing one. Then click Next.

   To modify an existing transformation path, click Select and click the transformation path in the list that displays.

4. Enter a code and description for this transformation path.

   These entries are for your convenience. The name will be used in lists of geodetic transformation paths, and the description can help you remember any salient details of the transformation path.

5. Select the geodetic transformations that will be part of this path and then click Next.

   Add the transformations in the order that they will be used in this path. Available geodetic transformations are listed on the left. Their source and target datums appear below. Select a transformation and click Add.

   As you add transformations to the path, the list of available geodetic transformations is reduced to only show geodetic transformations where the source datum of the transformation is the (current) target datum of the transformation path. To remove a transformation from the path, select it and click Remove.

6. Enter a value for Accuracy.

   Enter a value to indicate the loss of accuracy (in meters) that applying the selected transformation might bring to target coordinates. This value is used to determine whether the accuracy of one coordinate operation is more accurate than another.

   Values are positive numbers and typically range from zero to 100. For projective calculations, which are considered exact by definition, the value is 0. The following table shows some recommended values.

   Method	Recommended Value
   Molodensky Geocentric Translation	10
   Abridged Molodensky four-parameter transformation	10
   Bursa Wolf 6-paramete transformation	5
   7-parameter Molodensky-Badekas transformation with multiple regression	3
   Grid File interpolation (All formats)	5

7. Click Next to see a summary of the geodetic transformation.

   To edit any displayed value, click Edit for that section. Make your changes and click Next to cycle through the remaining screens and return to the summary.

8. To make sure the transformation path works properly, click Test in the Geodetic Transformation Test dialog box and enter appropriate geographic coordinates. The conversion is performed using the new transformation path. AutoCAD Map 3D toolset displays and verifies the results.
9. When you are satisfied with the transformation definition, click Finish.