# Using Mergin Maps Mobile App


Our mobile app was redesigned. We are in the process of updating this content to reflect these changes.

In the last tutorial we created a new Mergin Maps project in QGIS with layers for surveying trees and hedges. You'll now learn how to:

  • Open the QGIS project in Mergin Maps mobile app
  • Set GPS accuracy thresholds
  • Switch between layers to capture new point and linear features
  • Sync and save your data in Mergin Maps cloud


Need help navigating Mergin Maps mobile app? Mergin Maps mobile app Interface contains the overview of the functionality of the app's buttons and features.

# Opening the project on your mobile device

  1. Open Mergin Maps mobile app on your mobile device

  2. Open the My projects tab of the Projects page

  3. Download the trees-and-hedges project:
    Downloading project from Projects tab

    The project should now be downloaded to the device:
    Downloading project progress bar

  4. Switch to the Home tab and tap the trees-and-hedges project
    Open downloaded project from Home tab

    The project should now be shown:
    Project opened in Mergin Maps mobile app

  5. Pinch the screen to zoom in on your location. If you lose sight of your location, use the GPS button to recentre the map on your position.

# GPS accuracy

Current GPS accuracy affects the quality of field data that you capture in the field.

Let's see what can happen when capturing field data. Press the Record button:
Entering recording mode in Mergin Maps mobile app

You may now see a warning about GPS accuracy:
Low GPS accuracy warning

What does it mean? When GPS accuracy falls below a threshold, Mergin Maps mobile app reports this to the user using this warning. This threshold can be changed and it is highly recommended to set it to a sensible value as described below.

The mobile app uses a traffic light system to display GPS status:

  • Green: OK - GPS accuracy within defined threshold
  • Orange: Warning - GPS accuracy outside of defined threshold
  • Red: No GPS - there's no GPS signal or the GPS is unavailable

The current value of GPS accuracy, traffic light dot and accuracy bubble is displayed here:
GPS accuracy info in Mergin Maps mobile app

# How to change the GPS accuracy threshold

  1. Cancel recording and open Settings:
    Open settings in Mergin Maps mobile app

  2. Set Accuracy threshold to a sensible value
    Typical values could range between 2m and 25m and typically depend on the accuracy of your mobile device and your use case. Higher accuracy can be achieved by using external GPS antenna.
    Accuracy threshold setup in Settings

    Watch the traffic light change colour as you change the accuracy threshold.

# The active layer

In a moment we'll survey a tree. Surveyed features are added to the active layer. The project contains three different layers so we'll now ensure the trees layer is set as the active layer.

  1. Press the Record button:
    Entering the recording mode in Mergin Maps mobile app

    The active layer is shown just above the button bar:
    Active layer highlighted in Mergin Maps mobile app

  2. Tap the active layer and set it to trees:
    List of editable layers

  3. Press the Add Point button to survey a new tree.

    Notice how the form (e.g. species drop-down list) reflects how we configured the project in QGIS:
    Drop down form in Mergin Maps mobile app

  4. Enter some values and Save the new point

# Editing features and the preview panel

Tapping a map feature shows its preview panel.

  1. Tap the tree you just surveyed:
    Detail of surveyed tree

    Information shown in the preview panel can be customised. We'll learn how in the next tutorial.

  2. Experiment with editing the tree's species and location using the edit button:
    Edit button icon

    The edit button can be used to edit the feature's attributes (e.g. species, condition) and even its location/geometry.

# Survey linear features

When creating the project in QGIS, we included a layer for linear features called hedges. We'll now learn how to survey lines in the mobile app.


Areas can be captured in a similar way to lines if the project has editable area/polygon layers.

  1. Set hedges as the active layer.

    Refer back to the active layer section if you cannot remember how to do this.

    We'll now survey a hedge feature.

  2. Use tools in the bottom panel to survey the line: use Add Point to add points along the line and tab Done when finished
    Surveying line feature in Mergin Maps mobile app


Drag the map to position points manually or press GPS to recentre the map on your location.

  1. Enter some attributes and a photo for the hedge:
    Feature form in Mergin Maps mobile app

When I surveyed my hedge, it was quite difficult to distinguish from the background map - it was a thin, light green line:
Poor symbology of feature on the map

We will learn how to change layer styles in the next tutorial.

# Saving data to the cloud

To conclude this tutorial we will push the data we just collected back to Mergin Maps.

  1. Open the Home tab of the Projects page
  2. Press the sync button:
    Synchronising changes to Mergin Maps cloud

When the sync process has completed your data has been stored safely in the cloud.