The 3DR GCP app is an Android app that’s integrated with the Trimble Catalyst platform. With it and with Trimble’s low-cost digital Catalyst antenna, what used to be an expensive, time-consuming workflow for shooting accurate Ground Control Points is now as simple as the press of a button.

What you'll need

  • An Android phone or tablet
  • An active Site Scan account
  • An active Trimble Mobile Manager account
  • A Trimble Catalyst antenna
  • The 3DR GCP app downloaded from the Play Store
  • The Trimble Mobile Manager app downloaded from the Play Store
  • The Trimble Catalyst Service app downloaded from the Play Store

Setting up your app

Make sure you've downloaded all 3 apps before you get started. The Trimble Catalyst Service app will run on your phone's background but won't have a user interface app. You can check if you've installed it correctly by navigating to your Settings>Apps>Trimble Catalyst Service.

Next, navigate to your 3DR GCP app. As a first time user, the app will display two splash screens that will request access to photos, media, and files on your device, as well as your device's location. Once you've accepted, you'll have to enter valid Site Scan credentials and follow the instructions on the welcome page.
Connect the Catalyst antenna to your phone/tablet via USB cord and to an external power source.

In the Antenna Configuration page, your default RTK Settings will be set ToGlobal. On this page you'll also be able to select your preferred antenna height (the default will be 2m). When you click Connect, you should see a pop up once your antenna is properly connected. If you can't connect your phone/tablet to the antenna, make sure it's plugged into an external power source.

If you're not yet signed into your Trimble Mobile Manager (TMM) account, you'll be redirected to the TMM app to enter your credentials. 

If you're already signed into your TMM account, the 3DR GCP app will display a "Connecting to Service" message, followed by a "Starting N-trip Service..." message, and finally a "Starting Survey..." message.

Make sure your TMM app and your 3DR GCP app aren't running at the same time, otherwise your 3DR GCP app won't be able to work appropriately.

Once everything is paired and working correctly, the app will redirect you to an atlas view, from which you can select any of your existing Site Scan projects by clicking on the hamburger menu on the top left corner. 

If you're not a first time user and you're accessing the 3DR GCP app again, make sure you click on the Connect button from the right hand corner.

In your atlas screen, you'll see the number of GPS satellites your app is getting data from, as well as the accuracy distance you're antenna is currently getting. If you're curious about the coverage area accuracy for the Catalyst antenna, visit Trimble's info page

The 3DR GCP app automatically connects to N-trip servers to increase the accuracy of your readings, but you can change those settings if needed by clicking on the three dots on the right hand corner and selecting your settings button.

Once you select a project in the app, you'll see if it has any GCPs attached to it. If you'd like to add a new GCP point to the list, click on the Add Point icon. You'll be able to adjust the label and add a description to your new GCP.

If you'd like to add a new GCP set to your project, click on the New GCP Set icon. Keep in mind that if you add a new GCP set, it will be used as the default for that project moving forward and the data from your previous GCP set won't be usable. 

Collecting GCPs is now easier than ever thanks to the 3DR GCP app and Trimble's Catalyst antenna.

If you want more information regarding the 3DR GCP app, check out our app release blog post

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