Best Practices: Project Base Point and Survey Point

Experiment using a sample model

The best way to understand how the project base point and the survey point work is to experiment with them. Download this sample model to play with. It contains spot coordinates based on survey points (black) and project base points (orange).

In the model, open the site plan view, and try the following:

• Rotate True North.
• Move the project base point.Also try moving the project base point back to the startup location (the internal origin).
• Move the survey point when it is clipped, and again when it is unclipped.

In each case, notice the following:

• Which spot coordinates change?

  Remember: the black spot coordinates are relative to the survey point, and the orange spot coordinates are relative to the project base point.

• Does the change affect Project North? or True North?
• Does the survey coordinate system or the project coordinate system move in relation to the model?

This type of hands-on experimentation is one of the best ways to understand these important positioning mechanisms.

Use the visibility of Project Base Points and Survey Points in linked models

When working with linked models the Project Base Points and Survey Points of the linked model are shown in gray. Use these points to help you understand the relative positions of the host and linked models Project Base Points and Survey Points.

For additional information see: Display the Project Base Point and the Survey Point

Check the model's distance from the internal origin

To ensure accuracy of the model, the model geometry must be less than 32 kilometers or 20 miles from the startup location of the project base point (the internal origin). To check this measurement, do the following:

1. To measure the distance from the project base point to the model geometry, use the Measure tool on the Modify tab.
2. If the distance exceeds the maximum, move the model geometry within 32 kilometers or 20 miles of the startup location of the project base point.
3. Move the project base point back within 20 miles of the startup location.

Position an imported DWG site

If a civil engineer provides a DWG file that contains site information for your model, do the following to ensure that the DWG file is positioned correctly:

1. Define the survey point using the coordinates from the civil engineer.
2. Rotate True North to specify the correct angle in relation to the model.
3. Import or link the DWG file.

   When linking the DWG file, for Positioning, specify Auto - By Shared Coordinates.