The last month I have had to walk a lot, so I created a 4 camera rig. The purpose is that I can walk the same trip, in time in each direction, and in theory get 8 images that will form some sort of a panorama. Not something I can stitch together, because the images are not taken at exactly the same time and the GPS is not precise enough to match the two tips. But they create a lot of images for Mapillary.
It looks like this:
The cameras a angled with a 45 degree difference, at -45 deg, 0 deg, 45 deg and 90 deg.
In the ends I have two Xiaomi Yi, at 45 deg (white one, with bottom up) a Sony HDR-AS100V and at 0 deg a Garmin Virb Elite. Each has a 64 GB memory card, because I hate running out of space and the price difference up to 64 wasn’t that big.
Each take an image every 2 seconds and I start them manually. I have learned, that every time I start them, I’ll have to check that they run - AND check them every 5-10 minutes. It is easy to hit the button wrong, or a camera might have run out of power or just gotten into a bad mood. When 4 times as many cameras you will have about 8 times as many failures.
They are mounted on one of the metal bars with holes you can get at the hardware store - don’t know the english name, but they are cheap and works great. I got the screws from dealextreme.com. Note the rubber o-ring under some of the screws. It will keep the cameras much better in their position than without, and especially the Xiaomis does not respond well to a tight screw.
When I get home
I create a folder named after todays date. I create a sub folder in each named after the camera and its angle, e.g. yi-45deg. Then I always knows what it contains.
I use the GPS from the Garmin, because it is better than my phone. So I use exiftool to create a gpx file from the images (See http://www.sno.phy.queensu.ca/~phil/exiftool/geotag.html#Inverse).
I use GPSPrune to watch that gpx trace, because the GPS may create bad points or drift completely.
Then I geotag the other folders and runs Mapillarys interpolate direction script, with the degree correction of each camera. Then I run the remove duplicates script, also from the Mapillary repository, then time split (from same repo). I then look at the first+last 5-10 images from each sequence, because they often contains a hand that is turning a camera on or off. Some times I look at more images and some times I run a script that remove all images with slow shutter speeds. When done, I upload.