My way of mapping us typically to take a detour, whenever I’m going somewhere. This means that I end up having “hotspots” around typical points of departure/arrival, i.e. my home, my workplace, etc.
So questions is, how many times do we want to take the same road? Should i avoid having the same stretches photographed over and over? - OR, should I just let the camera run, as it gives input to the point cloud generating algorithm, thus improving it over time?
My “project” is to cover my home town in its entirety, but when are we “done”, when I’ve taken every street once? Or when it’s been taken in both directions? Or maybe, when it has been done at least n times, in order to stitch pictures together properly?
I guess I’m both looking for community input on the subject, as well as input from the Mapillary organization on how they like to be kept feed
as many times as you like, for e.g. the point in time feature.
But it is based on your opinion, how often you should take it. IMHO it is needed a few times, to get all areas of the road without cars in the way, also in winter, spring, summer, autumn, also with construction work going on,…
I do a road a few times in the beginning (if possible) and later on every few month ago, if I do ride it again.
I try to avoid to get to many pictures of the same road. I also try to plan my trips with detours on the way between home and work.
Should I just publish all the pictures, it would become very obious where I live and work. And I don’t know if that is smart or not. So most of the time I skip the beginning and the end of my trips.
But beside that problem, I think you can take as many pictures as you want.
I avoid taking pictures many times of the same place/same angle in a short period of time. But I am sure Mapillary is going to be happier if you just let the camera run. That 3D structure point cloud that Mapillary is building is just going to get more awesome the more pictures you feed the system with.
In the short run the street view navigation is going to be a bit more messy, at least that is my experience. But I assume Mapillarys system is going to get smarter and smarter, and then that messy stuff will sort itself out.
So, if you are interested in a dense pointcloud, feel free to add many images. They contribute to the stability of the rest of the images.
Otherwise, some frequency of days or weeks is more appropriate to document changes in the environment, I normally pull out the phone when there are new buildings or other changes.
These are my standards for taking photos in dense urban environment (for example city center):
My “base” scan of a street is in 4 directions: forwards, backwards, left and right. For forwards and backwards, it’s often enough with 1 photo per 10-25 meters (1-2 seconds between photos at 30 km/h). Sideways requires a lot more, depending on the distance to the features (width of the street), 1 photo per 2-5 meters (2-4 photos per second at 30 km/h, or 1-2 seconds between photos at 7 km/h).
Of course if objects or lighting are blocking a good view of the street, or when there have been changes, I return to take more photos.
Recently, I’ve also started taking photos at 45 degree angles, which means another 4 times through the street. It seems the Mapillary site prefers 90 degree angles for morphing from one photo to another, but many details are not so obvious at 90 degree angles, so especially for OpenStreetMap editing the 45 degree photos often are valuable.
Thanks for the comments so far, let me try to be a bit more specific…
I do reckon the part of taking the same street in different directions and when changes has occurred in the physical surroundings.
In my experience, taking pictures mostly in a build up environment, I think it’s more tricky than that…
Sometimes there is better GPS positioning than other times.
Sometimes there is more or less traffic. If you can be in pole position for a traffic light, the next stretch can be pretty unobstructed, while the next segment is crowded by somebody overtaking you.
Getting the exposure right for a long street segment might be achievable, but when you pass crossroads that allow the sun through between buildings, a few pictures might be overexposed.
Shadows on buildings do change the pictures significantly, i.e. which side of the road is in sun or in shade.
So, I think that my philosophy is in general to let the camera run, but when we get to the point that “hot spots” are created by 12-15 or even more traces of the same route appears, then I favor to switch the camera off.
As Mapillary is now, there is no good way to select a sequence for a certain time. Multiple angles can also be confusing at times. Further more alle images are shown. This points to trying to limit number of sequences, angles and deleting bad images.
I imagine a future Mapillary where the software is much better at guessing the exact location and angle and where some human or automatic system helps hiding bad images. Further I hope for easier navigation. This is all in the future, but here you should just have a lot of cameras pointing in many directions, taking as many images as you can.
My suggestion:
If you take the same route, point the camera in different directions. If you get 8 angles for a sequence, you should have a decent panorama. There are also many seasons: Summer, fall, winter, spring. Sunny, cloudy, busy, no people. Everything documents a different aspect. So I actually think there is room for a lot of images of each stretch.
I try not to do the same section of road more than once a month. Other than that, I just go for it. And like others, I also look for different routes from point A to point B, although before Mapillary I did that anyway, just for the variety (now I just do it more often).
I think this would be an example of what @peter was referring to. I don’t do it every work day but I do it quite often.
@peter This section would be great for playing with some change over time AI stuff. Tennessee DOT just started a project to rebuild this stretch of highway to freeway standards. We don’t believe in things being flat here so they have some big hills to deal w/ including building a 53 foot retaining wall.
