There are many data collection tools you can use to gather the information required to make maps, depending on your needs and resources. Working in Dar es Salaam, the Ramani Huria team have developed a systematic approach to collect data from a variety of sources and allowing us to have develop accurate & sophisticated maps. In this how to blog post, we will give you information about the tools we use specifically to map flood-prone wards of the city and the collection of data for flood resilience. All the data collected with these tools is shared on OpenStreetMap (OSM).
Data collection tools are the instruments and devices used to aid the process of gathering data and it’s vital for our mapping process that these tools can capture the information required, be usable by our mappers, and perform in the daily environment of Dar es Salaam. Our mappers, students and community members, use a range of tools including:
- stand alone GPS devices
- field papers
- note taking i.e. pen and paper
- mobile apps including OSM tracker
Together these tools allow us to collect the information we need and produce useful maps for the communities we work in. Many of these tools are accessible for anyone to use and we’ll tell you a bit more about how you can use them to create maps.
Stand alone GPS devices
GPS stands for Global Positioning System, a satellite-based navigation system made up of a network of satellites that function in any weather conditions, anywhere in the world, 24 hours a day. Put into orbit by the U.S. Department of Defense GPS was originally intended for military applications but has become available for civilian use. By receiving signals from satellites orbiting the earth, GPS calculates your exact location and provides it in coordinates of two numbers: longitude (how far west or east you are) and latitude (how far north or south you are). We use GPS devices with Ramani Huria because they are highly accurate and very simple to use by our mappers, regardless of experience. There are also small and lightweight making them easy to use wherever our mappers are in the city.
Ramani Huria mappers using a GPS unit in Ndugumbi ward PHOTO CREDIT: Ramani Huria
There are a range of GPS units that you can use and they function in much the same way. The units used by Ramani Huria are similar to those pictured above and allow our mappers to easily navigate their location.
How to use a GPS unit
Ramani Huria uses Garmin GPS units, here’s a guide using the tool in your mapping.
- Turn the unit on by pressing the lower button on the right hand side labelled ‘light’. Once the device is turned on, it will start receiving satellite signals.
- Using the joystick, navigate through the menu and select ‘Satellite’. A new window will pop up which will tell you the accuracy of the GPS unit and your current position. Ideally your accuracy should be 5-3 metres, you may need to stand still for a little while for the accuracy to improve.
- Freely move around as you collect information and whenever you would like to take a point of reference or save a location, select ‘Mark Waypoint’ from the unit’s menu. The GPS unit will save the location. By default the locations will be numbered but you can also customise the name of the location. For later reference, it’s also a good idea to write down in a notebook the name and tags of any waypoints you save.
- A series of locations that you move through, creating a path, are called tracks. You can also save these on your unit. Tracks are useful for mapping objects that are represented by lines or shapes, for example roads, drainage systems, or the shape of a field. As part of gathering information for flood resilience, Ramani Huria is mapping drainage systems, so this feature has been especially helpful for us. To see or edit your tracks, select ‘Track Manager’ and you will see both your current track and any other tracks you have saved. Click ‘Current Track’ to save your track, you can give it a custom name or leave it with the default name. Always ensure you save your tracks when you finish mapping an area!
- When you have finished mapping, ensure you turn off your device by pressing the ‘Light’ button. It’s important to turn the device off so that it does not continue to track your movements after you have finished data collection.
When you have finished data collection, it’s important to make this information usable, for example Ramani Huria uses JOSM to add the data collected to our maps. To do this:
- connect the GPS unit to a computer/
- wait for the computer to detect the device and display the files, for example, with the device above you will see a file name ‘Garmin’. Double click and you will see several files stored on the unit.
- Click on the file ‘GPX’ and this will display your saved waypoints and tracks you have collected.
- Once you have JOSM open, select ‘File’, then ‘Open’, and the choose the waypoints and tracks to import them into JOSM.
We will be releasing a ‘how to’ post on JOSM soon, but in the meantime, check out the official guide.
Field papers are pieces of paper that allow you to easierly gather data while in the field by printing a map of an area, drawing on it and adding notes, and then loading the paper back to JOSM before adding the locations to OpenStreetMap.
The Field Papers website allows anyone to create a multipage atlas of anywhere in the world. Ramani Huria is mapping the city of Dar es Salaam ward by ward but in order to allocate mapping tasks, we divide the ward into workable portions. With the assistance of GPS units, this ensures our mappers know exactly where to map in the field and makes the process very efficient.
A mapper with field paper and GPS unit PHOTO CREDIT: Ramani Huria
How create field papers
Using the Field Papers website, you can create field papers for anywhere in the world, perhaps you want to map your neighbourhood and upload it to OSM or maybe you’re visiting a new city. Here’s how to create your own:
Start by selecting MAKE or ‘Make yourself an atlas’
- Go to the Field Papers site: http://fieldpapers.org/. Creating an account is option but it’s a good idea if you would like to save the field papers you create online.
- Select the first option in the menu, ‘MAKE’ or click ‘Make yourself an atlas’. The next window will ask you ‘Where in the world is your atlas’.
Select the area you are interested in
- The next page will show the area you have requested on OpenStreetMap. Use the tools to select the specific area you would like. The buttons are as follows:
this tool moves the area selected on the map
this tool increases or reduces the coverage of the area you have selected
this tool reduces or adds the number of portions the area is split into, make sure you create a reasonable number of potions based on the atlas you are creating i.e. the map should be split into enough portions that is clear and usable
the top two buttons zooms in (+) or out (-), the bottom button centers the portions on the screen
Default settings for creating field papers once you have selected your area to map
4. You will see three tabs above the map, ‘Select’, ‘Describe’, and ‘Layout’. You will initially be on the ‘Select’ option giving you three elements to define from drop down lists.
- ‘Letter’ allows you to set the paper size, either A3 or A4. Most standard printers use A4 and this is also a more user friendly size for mapping in the field.
- ‘Landscape’ means that the portions will be wider than they are tall. If you would prefer ‘portrait’ (portions taller than they are wide), you can change this option from the drop down.
- ‘OpenStreetMap’ is the default option for source of the field papers. You can also select other options such as ‘black and white’ or ‘satellite’. Select the appropriate option for your mapping needs. For mapping conducting by Ramani Huria, we use satellite imagery so select ‘Satellite only’.
Once you have selected the appropriate options, click ‘Next’.
These settings will produce 4 landscape A4 field papers from satellite imagery
5. After clicking ‘Next’ you will go to the ‘Describe’ section which will allow you to name the atlas. You also have the option to make the atlas as private if you do not want it to be publicly viewable.
Selecting ‘Layout’ options
6. Clicking ‘Next’ again will take you to the ‘Layout’ tab. You can choose to add a UTM (Universal Transverse Mercator) grid and choose to either create ‘Maps Only’ (a full page map) or ‘Maps + Notes’ (a half page map with notes on the rest of the page). When you have selected your options, click ‘Finished’.
Rendering the atlas
7. Your atlas will then be rendered, and when completed a window will pop up. This window will show the portions you have created with imagery, with each portion having a unique label e.g. A1, A2, B1, B2. In the top left corner you will see the name of the atlas and the number of papers created. To save the papers, click ‘Download PDF’ in the lower right corner.
8. Your downloaded PDF will included overview information about the atlas as well as all the field papers you have created. You can either print the papers or keep them digital and use the filed papers to assist in data collection in mapping!
Note taking i.e. pen and paper
Note taking with pen and paper is always a useful compliment to any data collection tools. Mapping in Dar es Salaam Ramani Huria has found that pen and paper can also be very useful when there is no power, signal, or other tools run out of battery.
We advise creating and using data collection forms to gather additional data as you map, this can help you remember details of features you are mapping and is more efficient than noting all details in a GPS device, which can take a lot of time.
Sample of data collection form SOURCE: Ramani Huria
Above is an example of a data collection form Ramani Huria mappers have used. Before you begin mapping, be clear about what information you are looking to gather and design your form to assist you in capturing this information.
Mobile apps, including OSMtracker
There are a number of mobile applications that can assist you in data collection when mapping, one example used by Ramani Huria is the OSMtracker. This works similar to a GPS device and is designed to be a tracking tool for OpenStreetMap. This app requires GPS on your phone to be turned on and to have a working data connection while using the app.
Tracks, click ‘New track’ to start mapping
To start mapping, click ‘New track’. Your phone will ask you to enable GPS, this is required to collect data. Once enabled you will see a variety of options including a network signal bar, you may need to wait for this to turn from red to green, indicating the GPS has picked up the network.
OSMtracker menu on Android
As you move around the app will track your movements and from the menu you can select a number of options to add notes, for example take a photo, record audio, or make a text note. All of these notes will be geo-referenced and when uploaded show in JOSM exactly where the information was recorded. You can also add in information about features and waypoints.
Track list once stopped and saved tracking
While you are tracking, click ‘Stop & Save’ to return to the homepage. You will see the track you have just done (and any previously saved) listed.
Clicking on the track will give you a number of options including ‘Resume Tracking’.
When you have finished data collection in the field and are ready use your data, select ‘Export as GPX’ to make the information readable by JOSM. You can also share the data collected directly to OpenStreetMap.
Once you have exported the data as GPX, connect your phone to the computer. Once connected, located the OSM tracker file on the phone and copy to your computer.
Data collected by OSMtracker exported as GPX and imported to JOSM
After launching JOSM, you can open the tracks you have created, as well as any additional notes you saved while mapping. These notes are especially helpful in digitisation.
Now that you know more about data collection tools you’re ready to start mapping! Make sure you share your data on OpenStreetMap and contribute to the biggest community driven map of the world.