Setting Up a Local Site Calibration From a Topcon .gc3 File

If you use Topcon surveying equipment on your site and operate in a local grid system, you should have access to a Topcon control point file (.gc3) from your rover or software suite. 

This file type can be opened with Topcon's 3D office software. It must contain the parameters from the calibration that describe the projection of the project and the horizontal/vertical adjustments to set up your site for local grid processing.

The local site calibration setup must be completed before data or AeroPoints are submitted for processing.

Creating a new site 

To start, create a new site in your portal to upload your .gc3 file. From the Welcome Page, click on the +NEW SITE button.

Alternatively, you can create a new site within the DATA PROCESSING tab in the top toolbar.


From the dropdown menu, select CREATE A NEW SITE.

Proceed through the Site setup wizard for creating a new site to the Site coordinate System setup step.

Uploading a .gc3 file

Choose Local grid system, and select your .gc3 file to set up the site coordinate system.

Tip: You can also drag and drop the .gc3 file into the upload box.

Important: Local site calibrations should not use a geoid.  You can check this by loading your file in 3D Office, going to the Project dropdown, selecting Control points, and checking the bottom of the Coord. System tab.  If "Use geoid model" is unchecked and blank, you can continue.  If this is not blank, and a geoid is being used, please discontinue this workflow and contact Propeller Support.

Once the file has been uploaded into the system, you can view the calibration file and enter a test point (optional).

The default unit is based on the Location set before the Coordinate System section. It can be changed by clicking on Local system unit dropdown list.

After you have verified the information, click NEXT.

Note: If your calibration uses a geoid, the global height coordinate will not be correct. Please discontinue and contact support.

I still can't do it!

We wrote these articles to equip you with everything you need to get the job done on your own, but we understand that sometimes this isn't sufficient.

If you're stuck, you can connect with our support team by clicking the support button on the top right corner of your user portal.