To Process GPS Measurements

For this task you use the Calculation wizard to process coordinates measurements. You import the GPS sessions to the Survey database, and transform the new coordinates to the existing network.

Requirements

• The Survey database is configured, see Configuring Survey Projects
• The coordinates of the connecting points/base points are stored in the database.
• Instrument of type GPS, representing the coordinate precision.
• Field code list containing the field codes of all points that have been measured.

Creating the Calculation Project

1. In the AutoCAD Map 3D Maintenance workspace, do one of the following:
   • Connect to an enterprise industry model project that contains the Survey model.
   • Open an industry model drawing that contains the Survey module.

   Your System Administrator adds the Survey module to a project or industry model drawing in Infrastructure Administrator .

   Click Insert tab > Survey panel > Survey.

2. Select the Project Group, and the Project.
3. Under Select A Calculation Project, click Manage Calculation Project.
4. Under Calculation Project, click Create.
5. In the Create Calculation Project dialog box, enter a name, such as GPS Example 1, and enter a description, such as GPS Measurements.
6. Click Create, and click Close.
7. In the Survey main window, click Next.

Step 1, Calculation Project Settings

1. Click to display the Advanced Options. Do not modify the default values.
2. Click Next.

Step 2, Import Measurements

1. Under File Data Source, File Format, select Cplan RO.
2. Under Files To Import, click Add, and browse for the files (*.RO).
3. In the file list, select the GPS coordinate files.
4. Under Attributes, enter a field date, and an operator.
5. Select the instrument, such as <GPS name>.
6. Click Import.
7. Click the Show Measurement link to open the Measurement dialog box.
8. In the Measurement dialog box, on the Transformation tab, select a session, such as <GPS 1>. Click to show the transformation parameters.
9. On the Transformation Planimetry tab, you select the transformation parameters to be used. See also Transformation Parameters. The default settings are for a Helmert transformation, as shown in the following list.
   • Delta Easting: New.
   • Delta Northing: New.
   • Rotation 1: New.
   • Rotation 2: No.
   • Scale Easting: New.
   • Scale Northing: No.
10. In the Measurement dialog box, click Close.
11. In the Survey main window, click the Show Imported Files link. The Imported Filed dialog box displays all files that have been imported into the calculation project. Click Close.
12. In the Survey main window, click Next.

Step 3, Find Reference Points

Step 3, Find Reference Points, provides information that helps you to detect possible errors, such as missing base points, field coding errors, or point number typos.

1. Under Find Reference Points, click Find.
2. Under Information, click the Show Coordinate link. The Coordinate dialog box displays the reference points. The Planimetry Fix Point tab displays the existing base points. The Planimetry New Point tab displays the detail points that will be transformed.
3. In the Coordinate dialog box, click Close.
4. Click Next.

Step 4, Calculate Approximation

1. Under Calculate Approximation, click Calculate.
2. Under Information, click the Show Message link. Close the Messages dialog box.
3. Under Information, click the Show Coordinate link to open the Coordinate dialog box.
4. Click the Planimetry New Points tab. The tab displays the approximate coordinates of the each measured point.
5. In the data grid, click the Identifier heading to sort the points by their point number. Note, that some points have been measured several times, and that approximate coordinates have been calculated for each point.
6. Click Close.
7. Click Next.

Step 5, Find Identical Points

1. Under Find Identical Points, click Find.
2. Under Information, click the Show Coordinate link.
3. Click the Planimetry New Points tab. The tab displays the approximate coordinates of the new points.
4. In the data grid, click the Identifier heading to sort the points by their point number. All point numbers are unique. Double measurements have been merged. Click Close.
5. Click Next.

Notice that by default, step 6, Find Existing Points is skipped, and the Calculation wizard continues with step 7, Calculate Adjustment.

See also Find Identical Points

Step 7, Calculate Adjustment

1. Under Calculate Adjustment, click Calculate.
2. Under Information, click the Calculate Indicators link.

See also Analyzing Precision and Reliability.