Open Street Map - editing & learning

General cycling advice ( NOT technical ! )
matt_twam_asi
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Re: Open Street Map - editing & learning

Post by matt_twam_asi »

maximus meridius wrote: 13 Mar 2023, 4:22pmQuite possibly. The "truth on the ground" as you put it, may very well be vastly different to any legal rights. That's why I sometimes ride on the pavement. But if your point is that the intention of "allowed access" tags is to identify the legal rights of access then that is clear. My phrase "the law, land ownership, permissions" may have been too wordy for you, or unclear. But those three things may, or may not, overlap or combine to affect legal access.
Thanks, that's a fair challenge and one that I don't think is raised often in the OSM community. My understanding is that OSM leans heavily towards what is verifiable (either on the ground or via a permissive legal source, for example Definitive Maps to define PROWs). If a sign on the ground says 'Private' but there's a document to the contrary held in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying 'Beware of the Leopard', it's probably going to be marked as private in OSM.

There's a recent example/case study here and here. The farmer's intentions were noble, but we don't deny the reality of what is on the ground in OSM, and therefore the edits were reverted.
maximus meridius wrote: 13 Mar 2023, 1:23amInteresting, thanks for that. Notable that despite the idea that "access" tags are always to do with legal restrictions, the wiki article gives an example where "access=no" might be appropriate because of a physical barrier. In fact the section of the wiki article devoted to "access=no" is almost entirely concerned with physical reasons why that tag might be appropriate, rather than the legal ones which are supposed to be the reason for using an "access" tag. Hence why I suggest that a locked gate, being a physical barrier, would be a sensible thing to add to one end of the lane. And why an "access=no" tag might be appropriate (at least for a section of the track), as per the wiki article. Of course one may think that it can't be "access=no" because the farm workers need access. But the wiki article centres around the idea of "access=no" being use for work under construction. So the construction workers need access. It seems to me that "access=private" is actually appropriate there, except that of course will need updating once the work is done. But so would "access=no". The temporary nature of the roadworks notwithstanding. As some roadworks can last a long time.
You're right that access=no is more focussed on physical access, I consider it a subset of access=private. If you will, a "this is practically impassable" tag. My view is that if the locked gate were to be replaced with large slabs of concrete or a similar immovable obstacle, then access=no would be appropriate. But (in my opinion) it's often misused as closer to synonymous with access=private.
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

A friend who introduced me to osm has always held the view that osm shows paths that people actually use (he's a walker), whereas the OS series displays rights of way. As the screenhsot suggests, the local authority is the agency that holds the records and deals with queries - although thanks to the bankers' cavalier attitiude to risk, there'll hardly be any staff left these days to ask, I imagine...
screenshot of OS web page
screenshot of OS web page
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maximus meridius
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Re: Open Street Map - editing & learning

Post by maximus meridius »

matt_twam_asi wrote: 16 Mar 2023, 8:51pm
maximus meridius wrote: 13 Mar 2023, 4:22pmQuite possibly. The "truth on the ground" as you put it, may very well be vastly different to any legal rights. That's why I sometimes ride on the pavement. But if your point is that the intention of "allowed access" tags is to identify the legal rights of access then that is clear. My phrase "the law, land ownership, permissions" may have been too wordy for you, or unclear. But those three things may, or may not, overlap or combine to affect legal access.
Thanks, that's a fair challenge and one that I don't think is raised often in the OSM community. My understanding is that OSM leans heavily towards what is verifiable (either on the ground or via a permissive legal source, for example Definitive Maps to define PROWs). If a sign on the ground says 'Private' but there's a document to the contrary held in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying 'Beware of the Leopard', it's probably going to be marked as private in OSM.

There's a recent example/case study here and here. The farmer's intentions were noble, but we don't deny the reality of what is on the ground in OSM, and therefore the edits were reverted.
maximus meridius wrote: 13 Mar 2023, 1:23amInteresting, thanks for that. Notable that despite the idea that "access" tags are always to do with legal restrictions, the wiki article gives an example where "access=no" might be appropriate because of a physical barrier. In fact the section of the wiki article devoted to "access=no" is almost entirely concerned with physical reasons why that tag might be appropriate, rather than the legal ones which are supposed to be the reason for using an "access" tag. Hence why I suggest that a locked gate, being a physical barrier, would be a sensible thing to add to one end of the lane. And why an "access=no" tag might be appropriate (at least for a section of the track), as per the wiki article. Of course one may think that it can't be "access=no" because the farm workers need access. But the wiki article centres around the idea of "access=no" being use for work under construction. So the construction workers need access. It seems to me that "access=private" is actually appropriate there, except that of course will need updating once the work is done. But so would "access=no". The temporary nature of the roadworks notwithstanding. As some roadworks can last a long time.
You're right that access=no is more focussed on physical access, I consider it a subset of access=private. If you will, a "this is practically impassable" tag. My view is that if the locked gate were to be replaced with large slabs of concrete or a similar immovable obstacle, then access=no would be appropriate. But (in my opinion) it's often misused as closer to synonymous with access=private.
Thanks. I suppose here we are up against how deeply nested the structure of OSM can be. Or how deeply the designers were willing to make it. So though you think it's a subset (is that what you mean, it's a single tuple?), OSM doesn't, it's an alternative to "private".
mattheus
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Re: Open Street Map - editing & learning

Post by mattheus »

freiston wrote: 12 Mar 2023, 10:24pm That's a different take on previous posts than I had. I didn't take "IT wunder-kidz" to mean youngsters generally being tech savvy (as opposed to us older generations) but a rare and talented minority (probably younger rather than older) with a particular interest and talent in IT/computing/coding generally and digital mapping specifically. Similarly, I didn't take "us mere mortals" to mean anyone not young enough to have gone through school without modern computers or smart phones, but just those of us not so gifted.
[my bold]: yes!

I am of an age that my peer group at school/college are now far from young, and yet I know that some of them always had that talent/interest that set them apart*. And yet as teenagers, we were using tech invented by folks another 20 years older than us - those grey-beards are mostly sat in expensive armchairs now, probably still tinkering with some new thing that I would take twice as long to comprehend! :P

*of course it's really a spectrum, but that doesn't matter, as those at one end will still find certain tasks or tech easier than those lower down!

All these flavours of discussion (could be installing t*beless, or climbing a 20% gradient on the big ring, etc ... ) give a certain type the opportunity to arrogantly declare their own abilities with words similar to:
"if I could do it, it must be simple!"
Bragging without declaring yourself to be so :D

Anyway, monologue over. Fortunately these blow-hards are rarely blessed with the gifts of teaching, so I can happily ignore them (and indeed I have found the forum tech to assist me in this - a minor success, huzzah)
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

So though you think it's a subset (is that what you mean, it's a single tuple?), OSM doesn't, it's an alternative to "private".
For those interested, there is a description of how the database works, in broad terms, in the wiki.
https://wiki.openstreetmap.org/wiki/Database
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

Days afer I attempted to edit the nearby section of The Concorde Way to show its closure, it's still not showing in cycle.travel as closed. Have I done it wrong or is it that the data refresh into c.t takes place less often than I imagined?
screenshot of osm edit page
screenshot of osm edit page
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Richard Fairhurst
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Re: Open Street Map - editing & learning

Post by Richard Fairhurst »

The latter. c.t updates roughly every month from OSM; it's a long process that takes several days to do the website maps, the app maps, and the routing databases.
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

Cool... thanks Richard :-)
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matt_twam_asi
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Re: Open Street Map - editing & learning

Post by matt_twam_asi »

maximus meridius wrote: 17 Mar 2023, 12:00amThanks. I suppose here we are up against how deeply nested the structure of OSM can be. Or how deeply the designers were willing to make it. So though you think it's a subset (is that what you mean, it's a single tuple?), OSM doesn't, it's an alternative to "private".
I think we may be talking slightly at cross purposes. From the technical, database design view you can only have e.g. one access=* key per object (although one can bodge it by using ; delimiters). I'm talking about the conceptual idea of what each value means, which is built around community consensus and one's one interpretation. Here's some other access values that I consider to be different (and usually more specific) to access=private, and yet could all be conceptually grouped into the 'private' category in that they restrict access in some way to the general public:
  • access=customers
  • access=forestry
  • access=permit
  • access=destination
  • access=delivery
Again, this is just my interpretation. You may have a different one and that's OK.

It's also perhaps worth mentioning that access permissions in particular can be finicky in OSM - for example access=yes on its own infers permission to everyone and everything (including pedestrians, equestrians, cyclists, all other motorised and non-motorised vehicles etc. etc.) and therefore it's encouraged to think carefully when using generally permissive access tags. However, generally restrictive access tags are less of a minefield as it's safer to allow specific exceptions if needed. Anyone who's dealt with badly configured blacklists will know the pain of leaving something inadvertently open. ;) Of course, it may not matter either way if the downstream routers are well designed and consider other attributes, which I believe brings us full circle back to the original question.

Such is the fun of using a k=v system that allows users to add any key and/or value.
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Re: Open Street Map - editing & learning

Post by maximus meridius »

matt_twam_asi wrote: 20 Mar 2023, 5:05pm
maximus meridius wrote: 17 Mar 2023, 12:00amThanks. I suppose here we are up against how deeply nested the structure of OSM can be. Or how deeply the designers were willing to make it. So though you think it's a subset (is that what you mean, it's a single tuple?), OSM doesn't, it's an alternative to "private".
I think we may be talking slightly at cross purposes. From the technical, database design ...
From a "technical, database design" point of view a single tuple that contains the value "no" isn't a "subset" of a single tuple that contains the value "private".

We have just collided with the compromise that the database designers made. As they always have to.

Of course the values could be things like "private, no access", "private, contractors only", but then you haven't got atomic values, so the thing isn't even in 1NF. Depending what you consider an atomic value. It looks slightly better without the comma.

Though of course the OSM may not "really" be a relational database. Though I believe the base tables are stored in PostgreSQL.

Such is the nature of the compromises that designers of information systems have to make.
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

When I first came across digital databases and asked a trained colleague a question, his reply was, "It depends.". It wasn't the last time I heard that.
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Richard Fairhurst
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Re: Open Street Map - editing & learning

Post by Richard Fairhurst »

OSM's a community project rather than a computer science project really. As a result, the tagging model is full of redundancy, inconsistency and ambiguity. In that light working with the data can be... interesting!

Sarah Hoffmann (author of the Nominatim place search engine) and I did a talk on this at the OSM conference last summer: https://2022.stateofthemap.org/sessions/NAF9EN/
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

Jolly hockey sticks - I'll just go and pop the kettle on! :D
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simonineaston
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Re: Open Street Map - editing & learning

Post by simonineaston »

Just to say, I've watched the linked presentation which was interesting. I will watch some of others from the same (multi-day!) event. How entertaining to think of all you folks out there, beavering away on all this data and the way it comes together to make our lovely maps!! Thank-you!!
Another quick Q - well, two really. #1 Bristol's streets are chocka full of people living in vans - I know some of them and am not making a judgement here. With respect to osm, are their dwellings permanent enough to warrent appearing? Perhaps not individual vehicles but possibly instead, areas in which they are semi-perminantly parked.
#2 in your opinion, Richard, which is the most active and educational forum to read, that focuses on using osm, here in the UK?
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mattheus
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Re: Open Street Map - editing & learning

Post by mattheus »

simonineaston wrote: 26 Mar 2023, 3:22pm Just to say, I've watched the linked presentation which was interesting. I will watch some of others from the same (multi-day!) event. How entertaining to think of all you folks out there, beavering away on all this data and the way it comes together to make our lovely maps!! Thank-you!!
Hear hear!

(It's a bit like reading Wikipedia - I tend to take for granted the effort put in behind the scenes, so I've chucked in a couple of quid. But all these crowd-sourced facilities are a silver-lining to the evils of the modern internet x )
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