@pkoby, thanks for the details! We want to solve this problem for the generic usecase, so I will try to cluster the offsets in a time-calculated sequence in order to find the right offset-buckets (which are in this case not (-45 to +45 degrees, pointing ahead) and (-125 to -45 degrees, pointing to the left) but rather ahead and a bit more to the right. If I can find these values (let’s say assuming 4 buckets in total), we should catch most of the outliers that are creating the spiderwebs right now.
I have some other things to do today but will get back to this ASAP - this is a very good training ground for getting things right, and we want to solve this in a good way, for obvious reasons.
Thanks for the help @pkoby - I’m actually thrilled to finally get to this.
So,
today I hacked this little debugging html to see the recalculated sequences (different colors per sequence so you can see how they stretch and where they cross) before putting them into the backend system. This is the result after todays work @pkoby - look MUCH better. Now I’m applying this to the system, let’s see what you think!
This is a screen of 110.000 of your images in that area
So,
now the area is re-rendered and re-calculated using the latest version of our repair-algos. @pkoby please let me know if this is better than before - I even see you have some streets left to cover here and there, for instance Mapillary
The algo is not working perfectly on tight turns and varying offsets, but I think this is a good start for this iteration. we will work more on this, so expect some minor changes is some of the still falsely cut sequences, like Mapillary - we need to think a bit more about how to do the dynamic-range offset-clustering in order to catch these variations.
I will try to get to it, but for now, let me know if this is good as a start and proof-of-concept that we are able to repair the spiderwebs form old inconsistencies regarding sequences?
Good:
Looks like the algorithm is handling the issues better, and catching the correct sequence more often. I haven’t seen any sequences that bounce between directions.
Bad (and unfortunately some very bad):
Some sequences that are the only one in a day/ride are still split in weird ways. See this: Mapillary
As you mentioned, still some issues with tight turns, understandable.
I think you lost a lot of photos. Hopefully they’re still in the database?
Some of those empty roads showing up weren’t empty before. I didn’t note that these regions were broken or missing prior, so they seem to be just left out.
Here’s August 7th: Mapillary. Strangely, it seems to only have kept images with headings between 270 and 360 degrees (from both sequences).
Here’s August 9th: Mapillary. Same problem, but more directions (though mostly 90-180).
So what works seems to work okay, not perfect, but something bad happened to some dates.
EDIT: The missing images don’t load with a cache refresh or in JOSM, either.
@pkoby now I rerendered the whole area with dynamic clustering regarding the camera offset variations within a time-cut sequence, separating the 2 cameras quite nicely, please let me know what you think. Also, the 7/8th of Aug 2018 etc are back, see screenshot.
This definitely is an improvement. I’m still seeing some issues around tight corners, but again, it sounds like that’s tough for a computer to guess. There are also some weird short bits in sequences that don’t really make sense to me (e.g. here), but I don’t see any conjoined directions nor photos where there aren’t any, and those were the two big issues for me.
@pkoby I improved the algorithm for this a bit more, I think things are almost perfect now. Let me now if you have any more problematic sequences in this area, I have been training on these tracks: Mapillary
Thanks for the Feedback! I’m now trying to sort out the recalculation of tracks with more than 2 cameras with their own tracks which involves averaging the (e.g. 4) tracks and then calculating the offset against that track in order to reduce noise. When that is working, we are ready to reprocess the older imagery without shredding things.
It requires some more work but I think this is a first good step, thanks for the patience and testing so far!
Yeah, no problem! I went through all of August checking my tracks, and I notice that the sequences often split at traffic lights. I assume that’s because I delete photos during processing, so there’s a jump of a number of seconds. Other than that, I find no issues.
However, it seems like August 30th snuck through unprocessed, because it’s the only day that’s still switching between the straight and left directions, and has some spiderwebbing (Mapillary). Otherwise, all of August looks great!
Not all questions and remarks are directed to the Mapillary team. Sometimes messages are just a chat between users.
But I agree it would be nice to see a category “Questions for developers” or “General support” when users really expect an answer from the team, and not only from other users.
Good input, will try to push for that. If we do that I believe we need to be more stringent in not changing the topic too much, otherwise categories might fall short to describe the discussion adequately.
