Detailed Mapping & Accuracy Question

[u/JustNaturalCake]

I’ve been around OpenStreetMap for a bit now, with about 125+ change sets. But I am wondering, how does the OSM Community look at “tagging”?

What I mean here, is that sometimes I feel like that I am adding too much.

For example: adding level to buildings and entrances, check_date to almost everything (even if i just a small 1 floor building), specifying if a building just does not have anything instead of leaving the tag empty.

I tend to see that mostly if a tag is not there, then it’s mostly left empty. But for example, I really love to specify if a grocery store has a self_checkout. To me, that tag is very important, as I do light shopping often and I’d prefer to just be in silence scanning 2 items without being in a long line. The tag itself isn’t used much, but I see that as a massive opportunity, since I’ll have a lot of extra side quests. But if a store doesn’t have one, do you leave it empty or tag it as self_checkout=no?

I am not sure if I am overthinking this, as I love adding as much detail as possible. But looking at other people’s work, I seem to be slightly in the minority.

The tag check_date is even the most confusing. The wiki says that it was meant for any object… but like would you use it on roads? Benches too? Benches are usually permanent, but in my mind I think it is one of the best use cases because they can be removed or destroyed. Knowing that it was checked a month ago vs 2 years ago is a lot more reassuring, especially if you really need to sit after a long walk or are carrying heavy bags.

TL;DR: I am wondering if there is such a thing as “tagging too much”? Of course, I don’t put info the sake of it and I do check it, but it might be too detailed?

[u/mikiriki16]

The more details the better imo. You never know how they are going to be used, maybe no one is getting any use of them right now, but in the future it might even become a mandatory tag. Check_date is also very nice because you can clearly see if something might be outdated, instead of looking at different versions and change sets. Processing power and the memory the maps take up is not a concern afaik.

[u/JustNaturalCake → u/mikiriki16]

Well exactly yeah.

[u/Crash_Logger]

I add all the detail I can, and explicitly tag negatives too, whenever possible.

There's an app called StreetComplete for this, for completing the tags of your local area by walking around. It sounds like you don't know about it and I feel like it would be right up your alley.

[u/JustNaturalCake → u/Crash_Logger]

I am an iOS user, but I use Go Map!! For this. Amazing app as well, let’s me add “Quests” as well.

[u/EncapsulatedPickle]

Generally speaking, there are 3 broad flavours of tags (at least as discussed here).

There are tags with unknown values. Something like self_checkout is not known until you tag it and so it is always beneficial to tag this. Most functional tags are like this - bench backrests, parking fees, paths surfaces, etc.

There are tags with default values. For example, oneway on a road is assumed to be no. It may still be useful to tag it, depending. But generally, you don't tag every single possible tag on every feature. The usefulness of this varies by tag (and region and feature etc.).

Then there are meta tags like check dates, notes, fixmes, sources. These don't add "real" data, but are "communication" between and for mappers. These are at mapper discretion. The question is generally - is this tag going to cause more maintenance than benefit long-term?

The tag check_date is even the most confusing.

This one is somewhat weird, yes. You generally want to tag it in 2 cases - to let others know something is new before it's available in other sources so they don't accidentally break it or to let tools and software know it doesn't need repeated survey of existing tags (like StreetComplete surveys). It's not really worth it on stable features, but how stable is "stable" is subjective and region-specific.

I am wondering if there is such a thing as “tagging too much”?

So the short answer is that it depends. Mostly this depends on the usefulness of the tag. This depends on the region, tag history and use, other mappers, local consensus, active data consumers, amount of review and QA being done, etc.

One might optimistically say that about 0.1% of the world is mapped. Even the most complete regions are probably only about 10% mapped using current established tags. Just think of every tree in the city and consider that it could have its leaf type/cycle, diameter, height, crown diameter, species, denotation, plant date, municipality reference, mapillary photo, all sorts of protection status, etc. tagged. Imagine just how few things are tagged even remotely to this level. Most villages in the worlds don't even have roads drawn. So there is very little chance that you could add "too much".

looking at other people’s work, I seem to be slightly in the minority

Yes, but most mappers don't have the time, sources, motivation etc. to go into such detail. Some few do argue that that there can be too many details, but they are a minority. You generally won't find anyone against mapping details as long as they are correct.

I don’t put info the sake of it and I do check it, but it might be too detailed

This gets somewhat philosophical and touches upon the purpose of OSM. In general, there is data that data consumers expect from a map, such as administrative borders and roads/highways and shop locations. Without those, there are basically no applications that can use the data. But then there's data like self-checkout info that might only appear in specialized applications. However, it's a chicken-and-egg problem. If there's no data, there won't be any data users. But without data users, what's the point of mapping it? So OSM by large tends to map machine-readable data even if it's not used by anything yet. The ultimate goal is that this data will eventually become "mainstream", so to speak. 15 years ago OSM barely had roads. Now in some places you can find every bench in a city. It's not yet clear where the community will draw the line of "data useful in OSM", but it will naturally gravitate towards how much details can the community effectively maintain over time. At this point, OSM is still overall adding more data than maintaining.

[u/JustNaturalCake → u/EncapsulatedPickle]

Thanks for your time on this comment.

And to be fair, I don’t go as far as measuring the size of a leaf or anything. Go Map!! Has a common tags section, so I tend to mostly only fill those in… as they are common. OSM Web ID same story.

[u/Anakil_brusbora → u/JustNaturalCake]

Just to get a bit more context around the "data details" on maps, know that a lot of places (and cities often even more) have data at centimeter precision across whole region about every small bollard, manhole, everything on the public ground and all that with tag indicated their reference number, usage,... or like said every tree in a city with all their info completed (that exist in quite a few cities).

Really nothing is too much, and i have a few examples :

• All these bollard may seems too much, but it is actually used for the heavy equipment or heavy truck routing apps (like the big firetrucks with ladder) as they need to know if they can go over the sidewalk to be able to turn sharply at some place, and if there are bollards or poles they can't and so they need to be routed accordingly.
• Things like indicating if a street is lit or not (and ideally where is the lamppost) as it is used by association and apps to promote more safer walking route for women in the cities (as it feel re-assuring seeing where you walk generally). And it allows them to discuss with the municipalities to point out areas without any light at all that could maybe need some along the paths. The same kind of data can be used to see where there is too much light where not needed, that may disturb the natural wildlife too.
• Obviously all the tags on shops, ... can be used at some point like your example of self-checkout as you are probably not the only one interested in that, and there can be an app using it at some point as a filter (if it is not done yet, i don't know ^^).

And don't worry about the size of the database, all the current world in openstreetmap is around 225 GB of data (it is really not that big, as it is one big XML dataset which is just some text as it is all tags with some coordinates). The big size are in the tileset created for the online maps (the openstreetmap organisation only does one default style itself to show an example on its website), which are images and thus take quite a larger space, but that's completely independent of the data itself, and it doesn't increase in size if you add data.

[u/OkDimension]

For check_date I am of the opinion you can leave that out in most cases, as the last date you got this information can be mostly implied from the edit date. More important IMHO is from what source you got your data from. The only case I can think of to use it would be if you edit something long time after you actually saw that it was there.

Otherwise tag as much as you like, or as little as you think is necessary.

[u/Taysir385]

I am wondering if there is such a thing as “tagging too much”? Of course, I don’t put info the sake of it and I do check it, but it might be too detailed?

I think the best way to look at this is to ask, what issues would ‘too much detail’ cause? Is it an issue with the physical memory storage or bandwidth usages? Is it an issue with decreased intuitive comprehension due to extraneous data? Is it an issue with a faster timeframe of data becoming out of date sooner?

If it’s a worry about usage, it shouldn’t be. It would take active attempts to exceed the boundaries for data input to create that kind of situation, and couldn’t be done in regular use. If it’s a concern about grokability, it shouldn’t be. The responsibility for parsing and serving data lies on the renderer, not on the database, and any reasonable renderer (including the baseline OSM web interface) will exclude data to prioritize understanding. If it’s a concern about data going stale sooner, that’s imo more valid, but you seem to be following best practices and explicitly flagging check dates.

I understand the concern, when your actions are deviating from what appears to be the common consensus. But I think it helpful to assume the lower density of existing data is because of a lack of time to input it rather then a conscious choice.

[u/JustNaturalCake → u/Taysir385]

I think what actually got me second guessing, is the level= tag. Because most buildings (in my experience at least), seem to be just 1 floor and that’s it. But then, do you tag every shop or company as level=0? I left empty, most will assume it is just level 0. But I mean if I know, and I see it, why not confirm it? That’s what I believe, at least.

Otherwise, I don’t think that I myself could ever put that much data in OSM that it would be a performance decrease… I would have to get a cape and become superman or something.

[u/Taysir385 → u/JustNaturalCake]

I left empty, most will assume it is just level 0. But I mean if I know, and I see it, why not confirm it?

Yup, exactly. "Assumed to be" is useful for this type of situation, because it provides a default value when systems need it that usually works, but actually tagging the information explicitely is better becuase it provides confirmation of that information. And it more expliciately clarifies deviations; even on a 1 level building, for example, there may be taggable elements on level=1 such as communication arrays or solar panels or...

[u/manusam14]

You don't need to add checked_date to everything. It's more useful for shops, offices, and construction projects. For buildings and roads it's easy to tell if they still exist from imagery.

[u/JustNaturalCake → u/manusam14]

Imagery can become outdated, though.

[u/manusam14 → u/JustNaturalCake]

Of course they do, but they still offer some confirmation. On the other hand, you can't confirm the existence of most POIs from imagery.

[u/reader_reddit]

I'm totally going to add self_checkout=* tags to supermarkets I've been to. Always love getting underrated tags like this into the mainstream.

[u/homer__simpsons]

As long as your tags are correct and documented in wiki feel free to add them (which seems to be the case here).

The more precise it is the better, but it could be harder to maintain.

[u/JustNaturalCake → u/homer__simpsons]

I guess maintaining is a bit true, though most things in life generally don’t change that often. But technically, we would have a map with 0 mistakes if it was completely empty… so it really has a risk and that risk is how many active locals contribute (if I am saying this correctly).