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Tutorial: Field surveys using Mergin Maps

4. Capturing data and editing forms using Input

Accessing projects

1. Install the Input app from Google Play Store.

Once you open the application for the first time, it will take you to Home screen. This screen displays all the projects stored locally (under /sdcard/INPUT folder).

Input Home​

2. To access your projects on the Mergin cloud, select My projects. You will need your log in details to sign in to Mergin:

Login Input​

Once logged in, you can download your project to work on it locally by pressing download button to the right of the project.

3. Download the survey project from the previous sections by tapping the cloud with the downward arrow.

Input My Projects

The project will be available for loading in Input after you download it locally.

4. Select Home and you should be able to see your downloaded project:

Input homescreen

5. Tap the project under to open it in Input.

You'll now see one of the map themes.

Input project

Change background layers

We can change the background layers to be displayed using the Map themes that we created in QGIS.
6. Tap the More button Input more button.
7. Choose Map themes.
Input_more_menu

8. Choose Sentinel True Colour
Input map_themes
Input will now show the Sentinel True Colour image as a background map with the study area boundary on top.

9. Tap at the border of the Boundary layer polygon. The attributes will be shown.

Adding/editing features

Now we're going to add a feature to our survey layer (Groundtruth).

10.  To add a feature, tap the Record button Input record button from the lower panel. When you tap on the record button, it will list all the layers, you can edit. In our case that's only the Groundtruth layer.

Input survey layer

In Input, you have two modes to capture feature:

  • GPS location or streaming (if you are capturing lines/areas)

  • Free hand: by adding points or nodes to lines or areas

Capturing points

Our survey layer is a point layer, it will show a cross-hair at your GPS location.

11. Move the map to the parcel that you are observing and tap Add Point Input Add point button. The point below the cross-hair will be used as the recorded location. You can move back to your location if needed, by tapping GPS Input GPS button.​ If needed you can switch to other Map themes to better orient yourself.

Input Add point to parcel

12. Fill in the form. To fill in the current date/time automatically, tap the calendar button Input Calendar button. The fields that are depending on choices are displayed in red.
Input form

13. Tap Save Input save point button to save the form data to the attribute table of the survey layer.

Edit captured points

You might still want to correct  something in the form while you're in the field.
14. Tap the point you've just created. A preview will show up as defined in QGIS.

Input point preview panel
15. Tap the edit button Input edit button and edit the form. You can also tap Edit geometry Input Edit geometry button to change the location of the point. Tap Save Input save point button to save the updates. If you want to delete the item, you can press the recycle bin Input recycle bin.

Synchronisation of data/ projects


You can upload your changes through the Mergin service, once you have network connectivity.
16. Tap Projects Input projects buttonfrom the lower panel.
17. Tap My projects Input My Projects button
Now you see Input Sync buttonnext to your project.
Input automatically flag schanged projects with a synchronise icon.
18. Tap Input Sync button  to synchronize your edits with Mergin.
Input Synch my project

Similarly, if a project and its data has been updated through the Mergin service, you will be notified to synchronise the changes to your local copy.

Download the data into QGIS

Now we want to further process the data in QGIS.
With the Mergin plugin we can syncronize the project in QGIS.
19. Right-click on the project under Mergin, from the browser panel
20. Select Download
21. A new window will appear to set the folder path. Select the project folder of the original project.
22. Once the project is downloaded, select Open the downloaded project.

23. Check the results using the Form view of the attribute table.
QGIS Form view of the attribute table

Now you've completed this tutorial.
Below some instructions for capturing lines or areas.

Capturing lines or areas

If your survey layer is a line or area, the panel at the bottom changes to a figure similar to the one below:

​

You can:

  • Use Add point Input Add point button to define the shape of your line or area manually by navigating through the map

  • If you want to stream the GPS to shape your line or area, press and hold GPS button Input GPS button on the bottom left corner.

Once finished, press Done. If your feature is an area, it will join the last point to the first point to close the shape.