To start with, you will need to install the following software applications:
In addition, you will need to register with the Mergin service. The Mergin service allows you to transfer data between your PC/laptop and mobile/table via the cloud. Follow the registration help page to sign up to the service.
Configuring QGIS project
To be able to survey data, we need to set up a project in QGIS. Usually, you will need some data for your background layer (so that you can locate yourself!). In addition, you need to set up a table (or layer), to store your survey information.
For background data, we are going to use Open Street Map. For survey table, we need to decide on a form structure and the type of feature you want to survey (e.g. point of interest, tracks or parcel of land). In this case, we want to survey potholes. Also, it would be good to attach some notes for each pothole, take a photo of it and add a date for survey. The GIS format best suited to store spatial information, is Geopackage.
Let’s start by opening QGIS and add the above layers to our project. To simplify things, we can create a folder on Desktop (referred to in this tutorial as data collection folder) and store everything there.
Open QGIS from your PC/laptop. From the Browser panel (usually located on the top left side), expand XYZ Tiles and double-click on OpenStreetMap to add it to QGIS:
You should see the OSM layer:
Save your project as pothole survey in the data collection folder.
To create a survey layer, in QGIS, from the main menu select Layer > Create Layer > New Geopackage Layer …. Note that Geopackage is a file based database where you can store multiple tables (spatial or non-spatial). A new window will appear:
For Database click on … and select the data collection folder on your Desktop and then type survey-db.gpkg for the name of your database.
For Table name, type Potholes.
For Geometry type, select Point.
For Coordinate Reference System (CRS), click on the icon to the right of EPSG:4326 - WGS84. A new window will appear. Under Filter section on the top of the window, type: 3857 and under Predefined Coordinate Reference Systems, select WGS 84 / Pseudo-Mercator EPSG:3857. Then click OK.
We can now create the column headers for our table under New Field section. For this form, we want to create the following columns to store data: Date, Notes, Photo
For Name, type Date
For Type, select Date
Click on Add to Field lists to add your column.
Repeat the same process for Notes and Photos columns, but make sure to change the Type for those columns to Text. At this stage, you should see an image similar to the one below:
Go ahead and click OK to create the layer and add it to QGIS.
Styling layers and setting up forms
The default style applied to Potholes layer is not very visible probably. To change it:
In the Layer Panels right-click on Potholes layer and select Properties. A new window will appear. From the left panel, select Symbology. Try to change the style to something shown in the image below:
Click on Apply.
We can also change the way user fills in the form. By default, you have to type in the values. But by using different widgets, we can simplify filling the form in the field.
In the Properties window, from the left panel, select Attribute forms.
We are going to change the Widget Type for each of the Fields.
fid is an auto-increment field and we can keep it hidden from users. So, highlight the fid field under Field section and then from the Widget Type select Hidden
For Data, it should have automatically selected the correct widget type:
For Notes, you can also leave the Widget Type as Text Edit.
For Photos, we need to change the Widget Type to Attachment. Also make sure to select the option for Relative paths. This will allow us to attach photos using mobile camera or gallery folder to the pothole point.
Tip: You can scroll further down and under Integrated Document Viewer and select Type as Image. This will show the image in QGIS forms too.
Project set up is completed and we can save the project. Read further to transfer the data to your mobile device.