You cannot upload images to Mapillary unless they are geotagged, i.e. have location information written into their EXIF data. The Mapillary mobile apps do this for you, using your mobile phone’s GPS.
However, sometimes you might be capturing images with a camera that does not have a built-in GPS (such as the GoPro) and is not integrated with the Mapillary app. Or you might want to capture your tracks with a GPS device that is more accurate than a mobile phone or have a backup in case your default device should fail with recording the correct locations.
In that case, you can use an external device, like a GPS tracker or your mobile phone with a suitable app, to capture your tracks and combine that information with your images afterward. This will be done based on the timestamps of your images and the GPS track, so you should make sure your devices are synced on time. (This will make your life easier, but if you do have an offset then it’s possible to correct for that afterward as well.)
The best is if you can capture the GPS track in the .gpx format since it’s the most standard one and gives you the broadest opportunities for tools to use later. Many devices will provide that format, just check the producer’s information. You can also use your mobile phone with a GPS tracker app. We can recommend OsmAnd (available both for Android and iOS) which has a trip recorder plugin for logging a gpx track (check out the instructions for trip recording). But feel free to use anything else you like.
There are several tools available for combining the GPS track with your images. We found a good overview of the best programs for geotagging, which lists several that we know our community has been using, like Geosetter, GPSPabel, and HoudaHGeo.
If you’re comfortable with using a little coding, we also have a set of Python tools prepared for managing your images using scripts, including one for combining images with a gpx track.