Mergin Maps

# Creating a Project in QGIS

In earlier tutorials you created a new survey project from within Mergin Maps mobile app. That was a very fast (albeit limited) way of creating a Mergin Maps project. In QGIS, it is possible to create more complex projects and make the field survey more effective.

In this tutorial you will create a new project for surveying trees and hedges using QGIS.

# Before we start

Please ensure you have already:

# Create a minimal project

  1. Open QGIS

  2. Locate the Mergin Maps QGIS plugin toolbar in the upper navigation panel in QGIS. Click on the Create Mergin Maps Project button
    QGIS plugin Create Mergin Maps Project

  3. Choose the first option: New basic QGIS project
    Create Mergin Maps project: New basic QGIS project

  4. When creating a Mergin Maps project, we need to set:

    • a workspace (here: sarah). If you have multiple workspaces available, choose the one you want to use.
    • Project Name
    • The folder where the project should be created. Here, we use Documents\MerginMaps Projects

    Press Finish to create the project.

    Create new Mergin Maps project in QGIS

  5. Your new project should now be created and uploaded to Mergin Maps cloud.

    Close the dialog window to continue working with this project in QGIS.

    Mergin Maps project created and uploaded successfully

# Add layers

You may have noticed that the project we have just created with Mergin Maps QGIS plugin is very similar to the project created in Mergin Maps mobile app in the previous tutorial. This basic project contains a single point layer called Survey and OpenStreetMap as a background map.

TIP

Various background maps can be used in Mergin Maps mobile app, if they are supported by QGIS. You can learn how to add offline and online background maps here.

We will now add two more survey layers - a point layer for surveying trees and a line layer for hedges.

  1. Select Layer > Create Layer > New GeoPackage Layer...
    QGIS Create new GeoPackage layer

  2. Now we will create the trees layer:

    • Database: navigate to the project's folder and save the GeoPackage as trees.gpkg
      Here: Documents\MerginMaps Projects\trees-and-hedges\trees.gpkg
    • Table name will be set as trees by default
    • Geometry type: Point

    New GeoPackage point layer

  3. Add a New Field called date with the data type Date
    New date field

  4. Add two more new fields called species and conditions with the data type Text Data.

    In the Fields List, you can see the overview of added attributes and their respective data types. It should look like this:
    Field list with created attributes

  5. Click OK. A new layer called trees has now been added to the Layers panel.
    Point layer added to QGIS project

  6. Repeat steps 1 to 5 above to add another new layer called hedges with these details:

    • Database: Documents\Mergin Projects\trees-and-hedges\hedges.gpkg
    • Geometry type: LineString
    • Fields:
      • both_sides_surveyed, data type Boolean
      • num_access_gates, data type Whole Number (integer)
      • photo, data type Text Data

    Create GeoPackage line layer with defined attributes

Once you are finished, there should be two new layers on the Layers panel: trees and hedges.
Layers panel in QGIS with created layers

# Configure attributes forms

Before we try out this new project in Mergin Maps mobile app we will make a couple of small changes to the layers' form settings. The forms define how users interact with feature attributes in the field.

To illustrate how the form setup can affect the field survey, notice on the example below how the tree species, Black alder, has been accidentally mistyped during the field survey. This can be avoided by setting up a drop-down list (right image). Attributes can also be aliased (renamed) for easier reading.

Attributes form drop-down list in Mergin Maps mobile app

Now we will set up the drop-down list for the trees layer:

  1. Double-click the trees layer in the Layers panel to open the Layer properties
    Trees layer in QGIS Layer panel

  2. Select Attributes Form on the left and click on the species attribute
    QGIS Attributes form

  3. Make the following changes to the species attribute:

    • Enter the Alias that defines how the attribute's name is displayed in the form.
    • Change the Widget Type to Value Map
    • Enter Values and Descriptions similar to these (both are set the same in this example):

    QGIS Attributes form Value Map

    TIP

    Value is how the data will be stored in the underlying dataset and Description is how it will be displayed in the form to the user.

  4. Click on the fid attribute. Uncheck Editable option so that it can not be edited during the survey.
    QGIS Attributes form unchecked editable option

    TIP

    fid is a special attribute used to identify features. We recommend not allowing users to edit this attribute.

  5. The setup of the trees layer is complete. Click OK to close the Layer Properties window.

# Configuring photo attribute

The hedges layer has an attribute called photo. The attribute itself is stored as Text Data and we will use it to attach photos to surveyed features. To achieve this, we need to configure the photo attribute's Widget Type as Attachment.

  1. Double-click the hedges layer to open the Layer properties

  2. Select Attributes Form on the left and click on the photo attribute

  3. Set the form for the photo attribute as follows:

    • Widget Type to Attachment
    • Path defines where the photos will be stored. Set Store path as Relative to Project Path:
      QGIS Attributes form Attachment photo widget

  4. fid should not be editable. Click on the fid attribute and uncheck the Editable option.

  5. Click OK to close the Layer properties.

TIP

There is much more that can be done with the Attributes Form in QGIS when preparing a Mergin Maps project! You can learn more about forms in Setting Up Form Widgets, Advanced Form Configuration or other pages in the Configure Survey Layer part of this documentation.

# Saving changes to Mergin Maps

In the next tutorial we will see how this project looks on Mergin Maps mobile app. We'll now make some last changes, save them and sync the project back to the Mergin Maps cloud.

  1. Right click on the layer called Survey and find the Rename Layer option. Rename the layer to Survey notes (the name Survey is too general in this context).

  2. Save the QGIS project
    save QGIS project

  3. Use the Synchronise Mergin Maps Project button in the Mergin Maps QGIS plugin toolbar (it is located in the upper navigation panel)
    Synchronise Mergin Maps project in QGIS

  4. The Project status window will open. It contains the overview of local changes that were made since the last synchronisation: two layers were added to the project (hedges.gpkg and trees.gpkg) and some changes were made in the QGIS project file (trees-and-hedges.qgz).

    Click Sync to synchronise the project
    Mergin Maps plugin synchronisation Project status

In a few moments your changes are safely stored in the Mergin Maps cloud
Successful synchronisation of Mergin Maps project in QGIS

Synchronising changes between users and devices is a core principle of Mergin Maps. When you sync a project, changes that have been made by other users and devices since you last synced are fetched and any changes you've made are pushed.

Changes are merged safely and easily from different users, even when they edit the same feature. Mergin Maps tracks project version history so you can download a previous version of a project if you need to.

Public project available

The project created in this tutorial Mergin Maps Project documentation/t3-trees-and-hedges documentation/t3-trees-and-hedges (opens new window) is public. If needed, you can download it and compare it with your results.

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