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First let's talk about the hardware I'm using:

When outside, I carry two mobile devices with me: a OnePlus One and a Samsung S5. Occasionally I also have a Nexus 9 tablet with me, which is connected to a mobile hotspot. All devices run Android OS.

Easy and small changes

A very common task is adding a bench or trash bin or bollard to the map. That's always a one-time operation, and I found that MAPS.ME does a good enough job for this. On the plus side, it let's you select the exact position on the map, right where you are. You move a crosshair to where you want to add the new object. That is very useful and handy. Unfortunately the app has some limitations:

• It does not edit the object tags, like "backrest" for a bench. I have to go back to the online map later on, and fix this.
• It does not know about street lamps. The positioning functionality would make this the ideal tool to add missing lamps.
• It does not allow any additions in certain areas, like in a nature reserve. Not even a bench, or an information panel.

Small changes, offline

Another way to just capture something is simply take a picture. The "tag GPS coordinates" functionaliy is always enabled on my mobile devices, I only have to ensure that the GPS position is up to date. For that, I'm using the "GPS Test Plus" app (free version available as well). It shows you if the mobile device has a GPS fix, and how accurate it is. After getting the GPS fix, just take a picture and later on check the Exif data. Keep in mind that the stored coordinates are the ones where you took the picture, not necessarily the coordinates of the object you want to add or edit.

I'm using a file explorer to copy the images from my mobile device to an incoming folder on my laptop. From there I can use a picture viewer on one screen, and edit OSM on another screen in parallel.

Bigger changes, GPS tracks

When I cycle around and visit a new place, I track the path I'm going. The app I'm using is "GPS Logger", with modified settings:

• Logging Details
  • Log to GPX: enabled
  • Log to KML: enabled
• Performance:
  • Time before logging: 0
  • Keep GPS on between fixes: yes
  • Distance filter: 0
  • Accuracy filter: 20
  • Don't log if I'm not moving: off
  • New file creation: Every time I start

Note: this will burn your battery, because the GPS is on all the time and it will log one new data point per second, on average. For me I can run the app for 2-3 hours before I should head back and look for a charger.

However it also results in very exact tracking data. For testing purposes I tried this with both my phones in parallel, while I had to ... run some errands in a marsh:

OnePlus One

Samsung S5

For unknown reasons the S5 is more accurate. The resulting data points are more smooth and match with the path I was cycling. Occasional diversion from the path, especially if it is shown on both mobile device maps, is an indicator for a path in OpenStreetMap which should be updated/adjusted. A cluster of points is a good sign that I stopped there, and I should cross-check with pictures for more detailed information. The S5 is accurate enough to show me on which side of a street I was cycling.

You can upload the GPX file from OSM Logger directly to OpenStreetMap. Usually I upload the file into a tmp folder in my Google Drive first, by using the "Share" functionality in the app. Then I download the file on my laptop. After you uploaded the file to OSM, it takes a few minutes to process, and then it is available in your menu. If you click on the "Edit" link for a trace, you will see above map with your trace overlaying the OSM. That makes it very easy to edit the map and adjust it based on your movements in the real world.

This trace, along with GPS tagged pictures taken, enable me to edit OSM and add all the missing items I found along the path.