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Two mobile data collection apps you need to know about

Let’s revisit QGIS.  Why?  Its ecosystem is vast, and the two apps that plug into it, QField and Input, are well worth talking about.  If you do field campaigns, data collection, display your data offline, or have to synchronize it to a central database, you would be wiser for knowing about them.



Kurt Menke is the founder of Bird’s Eye View GIS, based in Albuquerque, New Mexico, USA.  He does a bit of everything from cartography and geospatial modeling to training.  Kurt is also a member of the QCooperative – an umbrella organization of QGIS developers, spatial analysts, and trainers.  They work together to provide QGIS support services for users who need new features or custom plugins.

QField? Input? What’s In It For Me?

These two QGIS project-based apps plug into QGIS, a free and open-source geographic information system.  They both honor the symbology and project settings that the users set up in QGIS and allow them to take project files to the field on mobile devices.  Once the data collection is complete, users can then go back to their desks and synchronize their project on their desktops or wherever they store their data.

QField, developed by a Swiss company called OpenGIS, is available for Android.  Input comes from Lutra Consulting in the UK and is now available for iOS and Android.

Setting Up Your Projects In QGIS

First things first.  Before any data collection in the field, you need a round of project planning and determine what you want to collect.  Both Input and QField allow collection of point, lines, or polygons, given that you set up empty layers and populated those with attributes you wish to collect in QGIS.

If you collect data on trees on a farm, you could for example to set up one column for species, one for the diameter of the tree, one for the data collector, one for the date, and so on.

QGIS’s attribute forms and widgets customize the data collection process by incorporating intelligence for data layers and columns before transferring data to a mobile device.  Suppose you set up a column called date and time.  You can add the default “now,” and it would auto-populate that column with the current date and time.

Another widget is called the value map.  It lets you create a picklist of different tree species that you may want to collect data for on that farm.

Checkbox allows you to check if something is true or not.  Constraints can be added and applied.  Sometimes you only need to answer a question if you’re mapping out a particular type of tree. The relevant question is triggered and appears because you answered and satisfied the previous question.

For instance, “Is this an oak tree?” If it’s a yes, then, “How tall is it?”

If it’s a no, then next item.

Does This Work For Existing Data Layers?

Absolutely. It’s a typical workflow with ongoing data collection efforts.  Collect the same data for months and add to the existing data set.  Most users, however, start from scratch with a brand new layer.

How Do I Prepare For An Offline Situation?

Map themes in QGIS allow the user to filter the layers that will be represented on the map.  You can use QGIS to create an inset or locator map.

For example, you only want to include the study area on the locator map, and you set up a map theme that’s just the study area polygon.  The rest of the layers become the main map.  Then you would go ahead and map the themeslocator, and main map.

Map themes can create an online and offline version of a map.  Users often use a base map, like an Open Street Map, and then generate MB tiles or vector tiles for the layers and set those up as an offline map theme.  Once out in the field, choose the map theme you’ll be working with, depending on your current situation.  The tiled layer will sit on the device itself and act as the background for the data collection.

At the preparation stage, it’s common to use GeoPackage to format vector layers and set up a folder for MB tiles.  All of the data and the QGIS project file are transferred to your mobile device, so when you open up QField or Input, it looks exactly as it does in the desktop version of QGIS.

How Do I Transfer The Project File Onto The Apps And The Mobile Device?

QField and Input are similar, with a difference. It’s worth noting that they’re both undergoing rapid development, so a difference today may not be the case a month from now.

In QField, there is a sync plugin with QGIS.  It packages your project as a GeoPackage into a folder you specify.  You then hardwire your mobile to your laptop and drag and drop that project folder onto the mobile device.

In Input, the plugin is called Mergin. It’s also a cloud service provided by Lutra.  A free account that comes with 100 MB of storage space needs to be set up online.  Once the plugin is installed, you can log in to your Mergin account and choose QGIS as a data provider.  Synchronize your project through Mergin, and it will upload it to your cloud account.  The Mergin cloud account is the middleman between your mobile device and your desktop.  It allows you to synchronize your project back and forth between the two.

Synchronizing Collected Data With My Central Database?

Once you’re done with data collection, Mergin lets you open QGIS.  Choose your  provider and synchronize your project from the cloud account to the desktop.  If you have things set up differently, such as your data is being stored online, the synchronization wouldn’t always be necessary.  If you’re working in a file or GeoPackage, Mergin will take care of that too.

OpenGIS is currently working on a cloud service for QField, and presumably, this service will be available very soon.

How Does This Work In Action?  Can You Give Us A Recent Example?

For the National Library of Medicine, we developed a project called Community Health Maps.  Public health workers, not your typical GIS professionals, were trained to use QField and Input for field data collection.  They then used QGIS for analyzing the data and mapping their process afterward.  The process is simpleintuitive, and easily accessible.  Users required minimal training in the form of a four-hour workshop.

In Miami, sea-level rise is becoming an issue.  How is this a public health issue?  The highest tides of the year are called king tides.  At high tide, the situation can be alarming.  Within the space of a couple of hours, you can have entire neighborhoods submerged in knee-deep water.  Water that could have a varying degree of bacterial contamination and salinity.  Just think about your children walking to school that morning, or your lawn being flooded by saline water.

Florida  International University set up a data collection protocol, but they needed help with turning it into a GIS format.  We translated their protocol into QGIS with the intention of using apps on mobile devices for data collection.  Data was collected on the depth of the floodwater, and water samples were taken for testing bacterial contamination such as fecal coliform and salinity.  Users were then trained on how to make maps that showed results for a particular community and how much contamination is in that floodwater.  This is an ongoing effort, and the program is still running, two years after implementation.

How Do You Even Manage Such A Massive Data Collection Effort?

At the time, technology didn’t allow us to clone and share a project database.  It would be much easier today with Mergin, for example.  It also helps to have a data manager assuring data accuracy and merge.

What About Visual Attributions? 

Users often need to take a picture and include a comment.  Both Input and QField allow for this, provided that a column was set up in the GIS layer in advance.  Once out in the field, you take a photo, and the designated column has a path to the image. Or you can use a photo from your gallery or from another app where you made a markup or circled something of interest. This is possible, and the function was utilized in Miami with the floodwater sample collection as a backup measure.  Pictures were taken of the water samples as well as the salinity meter.  Three shots were taken for every point that information was being collected on.

Is GPS Still The Best Way To Get Location? 

These apps understand GPS, and there is always an option of using a third-party Bluetooth GPS receiver.  They are more and more affordable and easy to use.  These increase horizontal and vertical accuracy and offer better signal lock. If you’re in a park with tree cover with no clear view of the sky, some of these receivers will lock onto the satellites better than a mobile would, for improved results.  Accuracy should always be your concern.

Phones use hybrid locational technology, locating by triangulating off cell phone towers or, slightly more accurately, in a Wi-Fi network, usually within a few meters of the true location.  If you have an assisted GPS chip, that’s the most precise, and if all three are accessible at the same time, the phone uses all three and an algorithm to pinpoint the location.  There is a lot of technology packed into these mobile devices these days, and we take them for granted. It’s surprising why there are so few studies on the accuracy of cell phones.

GIS chips are getting better and better with each version. Here is a more in depth discussion on the future of precise geolocation and smartphones.

It’s worth noting that you don’t have to be physically standing at the location you wish to collect data about. Users can simply move crosshairs to the desired location on the map and register data about that location.

Maybe you want to map something that’s behind a fence, like a bird’s nest, and you don’t want to disturb the nest.  You can be standing on the street next to the tree where the bird’s nest is.  Take the point anywhere on the map and later offset the point and put it in the desired location.

Data Analysis And Snapping

Currently, there is no snapping option with the apps – however, both Qfeild and Input are undergoing rapid development and we can expect to see more features being added in the future.

QField has a split tool that lets users cut a polygon in half or carve it up.  It also has a measure tool and compass integration, a bit like what you see in Google Maps on your phone when you want to see which direction you’re facing.

Crowd Sourcing GIS Data Collection And Citizen Science Projects

It’s exciting to see these open source apps come to the scene and collect data and perform as well as any proprietary data collection app.   They are available to anyone who wants to use them, like the Community Health Maps project.  They allow scalable solutions for community efforts, such as the one in Miami, where ordinary residents got involved because they were interested to see what we were doing in their neighborhoods.  We held an evening workshop in Miami, and people from the area were trained on our data collection protocol.  They installed the app and collected the data, which was supervised by experts.

It’s empowering to see how this project was personally affecting them.  This kind of scalability is only possible when you have something that’s free and open source.

Collaboration And Synchronization

Both of these apps can be further improved for collaborative editing for multiple data collectors and teams.  This will result in even better synchronization.  QField is working on this aspect, and Input is looking into metadata support.

Both OpenGIS and Lutra are responsive to user feedback, addressing bugs, and updating new versions.  The way they’re set up is ideal.  Their plugins and apps are not tied to QGIS versions.  The plugins can be updated as often as needed, irrespective of the current QGIS version.

Are you currently using apps for managing your projects on and offline?  Have they made your life easier?  Can you see how implementing them would be helpful to your team, or do you think this is just more effort, and you’d rather continue with how you’ve been doing things? I’d love to hear your thoughts.

About the Author
I'm Daniel O'Donohue, the voice and creator behind The MapScaping Podcast ( A podcast for the geospatial community ). With a professional background as a geospatial specialist, I've spent years harnessing the power of spatial to unravel the complexities of our world, one layer at a time.

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