gnesss's Diary

Recent diary entries

UK Quarterly project 1 2023

Posted by gnesss on 15 January 2023 in English (English).

Fifteen days in

Fifteen days into the year and the first UK quarterly project of 2023.

I’m quite encouraged by the early progress we’ve made on notes. As noted in the wiki page, there were just over 30,000 open notes at the start of the year. Right now that figure is 29,327. About 700 new notes have also been opened in that time, so that’s around 1500 notes closed already!

My own mapping efforts comes in peaks and troughs like I suspect many of ours do. Personally I’ve found this project quite fun. An open note can motivate me to help update the map as it gets me looking at the sources available whilst addressing the issue in the note.

So far my preferred way of browsing notes is using ResultMaps by Pascal Neis.

Types of notes

A few types of notes I’ve seen.

Nonsense, or notes used for non-mapping purposes

A fair few notes are clearly non-mappers who dropped a note on the map to share where they were planning to meet up, where they found random stuff or were otherwise planning work. Clusters of notes such as ‘Site Location’ ‘This is the place’ could be found in some cities, or ‘fungi?’ up a hill side.

Stuff that is already mapped

Many notes are highlighting new amenities, houses, roads, etc. These are then found to have been mapped since but the note not closed. An easy win for this project.

Partial info

A note that just says ‘closed’ or ‘paths missing’ is a good cue but would be much easier if it includes the business name that might have closed, or the vector of the missing paths at least - particularly in areas where some paths are already mapped. Or worse, a note that just says ‘Name changed’ with little indication of what was the old name, let alone the new one.

Street Complete generated

This is not a knock on street complete. It’s an invaluable tool. It does add a lot of notes though. In later versions of street Complete people are able to include a photo at least, which is hugely useful and the standard structure of the notes includes a lot of good information.

House numbers (but anonymous)

Anonymous notes with addresses are awkward. It’s useful info but I don’t add them unless I can cross reference them to other data. On a street where a dozen notes were added for house numbers, I could add the ones where mapillary imagery existed and showed house numbers, but the houses down a small cul-de-sac where imagery was not captured I’d not add.

This kind of extends to address info from non-anonymous notes. Do you just add addresses and house numbers from notes, or do you seek out an additional data point as proof?

OnOsm/business is here

See above. There’s many notes which say with their full contact details, but i'd not blindly add them to the map without street level imagery to confirm where they've placed the note on the map (it can sometimes be quite far off!) or even going to the effort of calling them to confirm. FHRS data and places where addresses are already mapped makes this *much* easier.

Always check.

Some of the notes are highlighting mistakes which have been present in the database for quite a while. I’ve resolved a couple notes which were along the lines of “This road is actually that other road. That other road ends at the previous junction”. With the aid of streetside imagery, it can be confirmed. A look at the history of the ways shows that they were mapped 10-14 years ago using NPE or Yahoo imagery.

Checking the history of elements that you may need to change is important. The older the note, the greater likelihood that it has been actioned, but independently surveyed on the ground found to have again changed. If relevant changes have occurred on the map since the note, I’d sooner leave a comment querying it than pushing ahead with armchair mapping. Even if it is well covered with aerial and streetside imagery.

Final thoughts

Street-level imagery helps so, so much. I especially appreciate mapillary imagery as I can associate a photo from a mapillary sequence with an item in the database. This has proven useful when resolving some notes along a canal for ‘water points’ and ‘service points’. Street Complete notes can include photos, but I think cannot be associated with items in the database in the same way. It leaves me uncomfortable to map something from an image that I’ve not personally surveyed, especially as a note vanishes from the map after 7 days of being closed/resolved.

Where I live, I’ve done a lot of mapillary coverage, but it is up to 5 years old in places. Considering how useful it is proving to be, I’ll be trying to update that.

Again, I’d like to know whether you would add to the map using data provided just from a note (anonymous or not) or from a website.

I hope we can maintain the progress we are making. This would put us on course to resolve ~ 9000 notes. This isn’t just a numbers game though. If you close 1 note but add 2 more to highlight areas of the map that need resurveying, updating or attention, that’s still improving the quality of the map.

Location: Brownsover, Rugby, Warwickshire, England, CV21 1PL, United Kingdom

Incremental detail

Posted by gnesss on 18 June 2019 in English (English).

Building the map up

Thinking about how data is contributed to OSM, an interesting problem is how the detail and level of information is increased over time. Some things are quite easy to refine, but others are definitely not.

Adding basic data

This appears to be straight forward. OSM makes it easy to add some data. Things like tracing aerial imagery to add roads, residential land use, parks. It’s rough data quality, but is not a problem, as to put assumed detail in would not be so helpful.. In the UK, it is increasingly rare to have a totally blank canvas to start with. It feels like most of the coarsest data of roads and villages have been mapped.

Improving data

Once new data sets are available, like street level imagery, further granular detail can be added. The ability to refine the coarsely entered data varies a lot, depending on what it is. A building being determined as a place of worship, or simply a detached house is easily done. change the tag, draw the outline or adjust the bounds if needed. Adding an address.

You can do this on one building on a street and it is an improvement, even if you haven’t done the rest of the street.

Some cases where it falls down

A few examples I’ve seen through my own experience or via talk-gb is where useful data could be added, but unless it is entered to a high level of detail throughout the vicinity, and in its entirety, instead of enriching the map, it can hinder its use.

Sidewalks and pavements

I love this kind of information, but it is difficult to add. You can add it as a tag to a way, or as a separate way. There are many long standing differing of conventions of where to add this data and where not to. The topic of sidewalks/pavements merits its own post. In the UK, sidewalks are generally not added at all, or only added if the pavement is separated from the adjacent road by something else. Routing engines seemingly assume most roads (motorways excluded) as possible to walk along. With the exception of some major roads and motorways, there’s no legal reason not to thing that, but plenty of practical ones.

But the point here is, if you only add the pavement as a separate way (or as tags, even) to a single road in a neighbourhood, it needs a lot of detail up front. Without that detail, it can be found to be not useful, confusing routing engines, data extraction and humans reading the map.

The ease of humans reading the map is interesting. Mapping for the renderer is not a great habit, but presentation of data for users is important, such that you can’t totally ignore it. Yeah, the renderer should be fixed instead, but with half a dozen rendering engines dominating the usage, there’s some convergence of how tags are being interpreted and drawn.

Road Junctions

A simple junction might first be mapped as a couple or more ways intersecting. To enrich this data, you can fairly easily be converted into a roundabout, or add turning restrictions.

It gets more difficult once traffic signalling is to be added, and exceptionally more difficult to add in pedestrian crossing points - particularly if the pedestrian crossing is split to only cross one direction of traffic at a time. Pedestrian interfaces to the road junction are hugely important and useful to have mapped - in my opinion. No one likes to find they can’t cross over the road from one particular side of the junction and could have done so had they crossed onto the opposite pavement 100 meters earlier. Or having to cross 4+ lanes of traffic where a traffic island could have halved that.

This is not something that can be gradually added to a map. You need certain things to be at a suitable level of detail before you can meaningfully add this adjacent data.

I like that openstreetmap allows people to map the things that interest them the most, but there’s clearly a hierarchy of detail where some items enable others.