A Look at Different Apps for Conducting Surveys: Part 3 (Locus Free)

by | October 12, 2011
Category: Blog

Android devices are powerful tools for surveying because they are multifaceted. We used them to conduct questionnaires, to navigate, and to measure the area of plots. For each of these processes, we used a different free application (or app). This post on the Locus Free app is the third of three posts on this topic; for Part I, our use of ODK Collect, go here; for Part II, our use of Distance and Area Measurement, go here.

With limited resources and limited time, most researchers cannot survey everyone within their research area. Instead, they take a representative sample. Many researchers use a “phonebook” sampling method in which they randomly select names from a list. Where we work, there is no comprehensive list of names, so phonebook sampling does not work well. Instead we chose a geospatially randomized sample.

For our sample, we generated 400 tiles each 500x500m that make up our 10x10km research area. We selected 40 of these tiles and wanted to survey every household inside of each. In Google Earth those tiles look like this:


If you think about it for a second, this method, while easier in some ways, does have incredible logistic and navigation challenges. When looking for Android apps to meet this challenge, we discovered Locus Free.

Why we used it
The creator of Locus describes it as a “multi-purpose tourist app,” so it might seem odd that an agriculture research organization would use it for navigation. At first it seemed strange to us as well, but it was the only app we found that met all of our requirements. These included:

How it worked
Each day, our enumerators would meet at the office, load up into our truck, and head out to a particular tile. When we generated our tiles, we numbered them, so it was as simple as telling the enumerators and driver, “Today please start by visiting tile three and then move on to tiles 4 and 5 as time allows.” Then the enumerator who was navigating for the driver would open Locus, select tile three, and use the compass and map views to navigate as near as possible to that tile.

Then the enumerators would disembark from the vehicle and proceed the rest of the way on foot. Locus displays a little blue location dot on the map to represent your current location, so the enumerators would walk until their blue dot was inside the tile. Finally, the enumerators would survey every household within that tile. If they walked to a house and found it to be outside the tile, they would simply not survey that house.

We used Locus Free version 1.13.3 on all of our devices.

Settings Adjustments
Locus Free is a very powerful tool with a large set of features. It also means that the app was not optimized for our purposes right out of the box. Incredibly, the app does allow for a lot of customization that we took advantage of.

Importing data points and shape files. After we generated our tiles in the .kml file format on the computer, we added a point roughly in the center of each tile[1]. We then uploaded the polygons and points onto the phones and into Locus.


Customizing the Locus home screen. Locus allows for almost any feature to be added to the home screen. Rather than navigating through a series of menus to find the features you want each time, you can permanently set them on the home screen. We chose our three most common features (View Compass, View Data Points, and Start Track Recording) and added them there.

Steps: Open Main Menu (click Locus Icon in top right corner) > Functions > Add New Button > Select feature you wish to add

Setting background map. We originally looked at Locus Free because of its ability to download maps for offline use. We were never successful in doing so, but we also realized that navigating without any map at all (i.e. a blank canvas) was actually less confusing for our enumerators. Once we realized this, we set the app to display a blank map rather than any of the default maps.

Steps: Open Map Manager (Map icon in top right corner) > Blank

Turn off “Beep on GPS Fix.” Locus is designed to let you know whenever the GPS has fixed in on your location. As a general rule, we tried to avoid extraneous pops, whistles, and beeps because they were not helpful for the enumerators and could be distracting during a survey

Steps: GPS button (third button from the right along the top) > GPS/Location Button (Orange button on top) > uncheck ”Beep on GPS Fix”

Set to “Use Hardware compass.” Locus’s compass determines its bearing in one of two ways.

There are tradeoffs to consider with both options. If you are surrounded by metal (i.e. in a car), then the second option is probably better. If you are walking, the first might be better for you. Because our enumerators were normally using the app while on foot we turned on the “hardware compass.”

Steps: GPS button (third button from the right along the top) > Sensors Button (Purple button on top) > select “Use Hardware Compass”

Ease of Use
This app is not easy to use. Even for a technophile or cartophile (map lover) the app has a learning curve. The User Interface (UI) is fairly intuitive and well designed; there are just are a lot of features and settings to navigate. Our long term plans include the development of an app that is more tailored to our needs and, therefore, more straightforward to use.

Our youngest enumerator really enjoyed using it. The app sparked his interest in navigation and cartography. Most of the other enumerators used it as necessary but never grew truly comfortable with it.

The advertisement at the top of the app takes up a large portion of the screen, so the free version may not work well on very small devices. Just be aware of it when testing out hardware.

Locus Free has a GPS on/off switch within the app in addition to the device’s GPS on/off. For Locus to work, both switches have to be turned on. Almost every time an enumerator was having trouble with Locus, they had forgotten to turn on the GPS in both places.

[1] These points are not necessary, but they were very useful because it is much easier to navigate toward a point rather than toward an area.

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