To Edit a Least Squares Input (LSI) File

The Edit Least Squares Input (LSI) File command provides an interface for editing or creating an LSI file. This command sorts the data in an existing LSI file into a more easily readable structure and allows you to specify standard error values for coordinates.

Prior to using the Edit Least Squares Input (LSI) File command, you can generate an LSI file to edit by using the Create Input File command. When you use the Create Input File command, all equipment precision values and standards errors are automatically generated, based on the survey equipment database.

You can also use the Edit Least Squares Input (LSI) File command to create an LSI file by entering field observations and the appropriate standard error values.

For a workflow of the process, see Workflow: Least Squares Analysis.

1. In the Toolspace, on the Toolbox tab, expand Miscellaneous Utilities Survey. Double-click Edit Least Squares Input (LSI) File to display the Edit Least Squares Input File dialog box.
2. Click and select the LSI file to open.

   By default, an LSI file that is created with the Create Input File command is named Network.lsi and is stored in \Civil 3D Projects\<survey database name>\<network name> folder.

   The file is opened in the Edit Least Squares Input File dialog box.

3. Under Coordinates, you can select the Fixed check boxes to fix certain points. Fixed points are not adjusted during least squares analysis. Coordinates in any row for which the Fixed check box is not selected are free to move.
4. Use the N Standard Error, E Standard Error, and/or Z Standard Error columns to add known error values to coordinate measurements.
   Note: The Fixed check box should be selected for any coordinate row for which you specify and want to apply standard error values.
5. Review and edit the data as needed. You can add a new observation by placing your cursor in an empty row in one of the sections of the dialog box and entering values. You can delete an observation by deleting each value in a row that contains observation data.
6. Click to save the file.

Continue the process of least squares analysis by processing the input file, viewing the output file, and updating the survey database.