Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
Martijn van Exel m...@rtijn.org writes: On Wed, Mar 25, 2015 at 3:00 AM, Minh Nguyen m...@nguyen.cincinnati.oh.us wrote: If you're lucky, you can find an Ohio city limit's legal definition in county commissioners' minutes when an annexation is proposed. The most authoritative data representation is the county GIS database, which anyone can easily access -- for a fee. After paying the county for that database, you might well forget about OSM, because it's also the authoritative source for road centerlines and names. That is actually not what I meant, but I could have been more precise. I guess this turns into a discussion of what 'authoritative' actually means. This is different things to different people. As OSM becomes better, increasingly folks will start looking at us for authoritativeness, which would make sense because everything is (supposed to be) verified on the ground. authoritative is a complicated word. One sense is the source that legally defines something. The other sense is what people usually mean with maps, which is about whether the map production process is such that a user can have a high degree of confidence Because administrative boundaries have legal implications, the authoritative source will need to be someplace outside of OSM. True, but I don't see the point. The authoritative source for whether a road exists is the fact in the real world, so that's outside OSM too. A map (database; that's not the point here) is a collection of useful facts, and except for maps published by entities whose word defines the world, no maps are authoritative in this sense. It's certainly true that no court would decide if a house is in a particular town by looking at OSM. I'm not sure if you're suggesting deleting all the boundary data, or just pointing out that most court cases will not use OSM data, or something else. It may actually hurt OSM down the line if we include information that suggests authoritativeness we cannot provide. I really don't follow your logic here. OSM has all sorts of information, and is the authoritative-as-defining source for essentially none of it. This is true of arguably every general-purpose map. Even the USGS map includes information where the Board of Geographic Names is authoritative. When I hear regular GIS people talk about authoritative data in the context of OSM, the concern is that anyone can edit and there is no QA process, so how can the data be trusted? This is compared to NAVTEQ (just to pick on), which presumably takes State DOT data and surveys/QAs it (so how can the data be up to date?). Whether the crowdsourcing process or the standard process leads to better data is not a settled question; there are valid arguments about the process both ways. (I find OSM data to be generally better in Massachusetts than e.g. the proprietary data that comes with a Nuvi, but in some places it's worse.) With respect to boundaries, careful curation of boundary information (from the law, as Minh suggests, or actual stones in my state) by OSM people leads to a good set of data, arguably as good as included in any other general-purpose map. So it's just the usual grand struggle to improve and add data, and I don't see why there should be any special concerns about authoritativeness. All of this has little to do with neighborhoods, which are mostly (?) vernacular in naming and delineation, and even when there are official neighborhood designations, in my own experience they do not always match the vernacular names. I support point mapping of vernacular neighborhoods. If you really want to have shapes for vernacular neighborhoods, you can look at the now-ancient-but-still-cool flickr Alpha Shapes[2], last updated in 2011 but still available for download[3]. But please don't upload 'em to OSM :) As a political boundary (in the political map sense), an official neighborhood designation can be distinct from the neighborhood with a vernacular name, but that's an argument to map both rather than favoring one over the other. They coexist and might share a name but aren't necessarily the same thing. People should be able to get the concrete, objective boundary of an official neighborhood from OSM and an amorphous, subjective boundary of an informal neighborhood from Alpha Shapes. Sure, but vernacular and official neighborhood objects would then need to be represented differently so folks can tell them apart and know what they are dealing with. That's basically admin_level=10 for an official neighborhood (I think Boston and Newton have these), and some sort of place=locality for things without legal boundaries. This is related to the hamlet discussion. One of the issues with OSM's place name schema is the confusion between place names and boundaries. Boundaries are actually pretty clear how they should be. But the place=town etc. talk about population, and you can't have population without a boundary. That probably
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
Serge Wroclawski writes: It's entirely possible that the names the locals use for that river differ from the government dataset, in which case, OSM would prefer you use the local name as the primary name, and not the official one. This is the USGS standard for naming in their topo maps. -- --my blog is athttp://blog.russnelson.com Crynwr supports open source software 521 Pleasant Valley Rd. | +1 315-600-8815 Potsdam, NY 13676-3213 | Sheepdog ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Wed, Mar 25, 2015 at 3:00 AM, Minh Nguyen m...@nguyen.cincinnati.oh.us wrote: On 2015-03-24 13:57, Martijn van Exel wrote: I have long been on the fence about boundaries in OSM, and while I don't feel as strongly about it any longer, it still feels wrong to make this sweeping exception to one of the fundamental conventions of OSM mapping: verifiability. For many types of land use, anyone would be able to verify boundaries on the ground: a forest, a corn field, even a retail zone in most cases. But administrative boundaries can only be observed in a limited number of places: wherever there is a sign or a physical boundary in place, and rare other cases. Admittedly, a given border can be observable along one segment but not another. However, we tend to map the entire border for the sake of completeness, convention, and technical reasons -- closed areas are much more useful than stray lines. OSM has long gone to extremes on this point, going so far as to enclose all continents and island nations in maritime borders. Hopefully you had the chance to read my case study on Illinois, Indiana, Ohio, Kentucky, and West Virginia earlier in this thread. [1] You can observe much of the Ohio-Indiana state line quite precisely, both on the ground via welcome signs and mile markers and from the air via changes in land use and pavement quality. But you cannot observe the Ohio-Kentucky state line except by visiting a library, and the Ohio-Ontario border is an imaginary line. Which of the five options would you have chosen for Ohio? [1] https://lists.openstreetmap.org/pipermail/talk-us/2015- March/014485.html I have, and my (admittedly much more limited) experience in Utah does not suggest I would be able to determine a reliable state boundary from information on the ground. County lines even much less so. More importantly though, there is an authoritative source for official administrative boundaries that can be easily accessed by anyone: TIGER[1] You mean the way TIGER is an authoritative source for road centerlines? TIGER's boundaries vary in quality just as its roads and railroads do. I've taken quite a few imported municipal boundaries, lined them up with road easements or hedges between farms _when that is obviously the intent_, and deleted extra nodes. These borders become far more accurate and precise in OSM than in commercial maps, which regurgitate TIGER boundaries verbatim. The most authoritative source for most U.S. land borders, going all the way down to the parcel level, is a legal prose definition in conjunction with any number of monuments on the ground. Both metes and bounds and the Public Land Survey System rely on monumentation. A monument may be a major road or as obscure as a small iron pin embedded in that road, but even that pin is verifiable if not particularly armchair-mappable. If you're lucky, you can find an Ohio city limit's legal definition in county commissioners' minutes when an annexation is proposed. The most authoritative data representation is the county GIS database, which anyone can easily access -- for a fee. After paying the county for that database, you might well forget about OSM, because it's also the authoritative source for road centerlines and names. That is actually not what I meant, but I could have been more precise. I guess this turns into a discussion of what 'authoritative' actually means. This is different things to different people. As OSM becomes better, increasingly folks will start looking at us for authoritativeness, which would make sense because everything is (supposed to be) verified on the ground. Because administrative boundaries have legal implications, the authoritative source will need to be someplace outside of OSM. It may actually hurt OSM down the line if we include information that suggests authoritativeness we cannot provide. All of this has little to do with neighborhoods, which are mostly (?) vernacular in naming and delineation, and even when there are official neighborhood designations, in my own experience they do not always match the vernacular names. I support point mapping of vernacular neighborhoods. If you really want to have shapes for vernacular neighborhoods, you can look at the now-ancient-but-still-cool flickr Alpha Shapes[2], last updated in 2011 but still available for download[3]. But please don't upload 'em to OSM :) As a political boundary (in the political map sense), an official neighborhood designation can be distinct from the neighborhood with a vernacular name, but that's an argument to map both rather than favoring one over the other. They coexist and might share a name but aren't necessarily the same thing. People should be able to get the concrete, objective boundary of an official neighborhood from OSM and an amorphous, subjective boundary of an informal neighborhood from Alpha Shapes. Sure, but vernacular and official neighborhood
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Wed, Mar 25, 2015 at 2:00 AM, Minh Nguyen m...@nguyen.cincinnati.oh.us wrote: I've taken quite a few imported municipal boundaries, lined them up with road easements or hedges between farms _when that is obviously the intent_, and deleted extra nodes. These borders become far more accurate and precise in OSM than in commercial maps, which regurgitate TIGER boundaries verbatim. The most authoritative source for most U.S. land borders, going all the way down to the parcel level, is a legal prose definition in conjunction with any number of monuments on the ground. Ah, another sticky wicket. There are many defacto boundaries created by roads, hedges, powerlines, ridges or bodies of water. I argue the most appropriate boundary in OSM is indeed the defacto boundary. If people are using, paving, weeding and farming the boundary, that's the one we can map. The legal boundary is not something OSM can adjudicate. Finding that boundary is a complex process involving survey points, land descriptions, and often handwritten records stored in dark basements. It also hardy ever matters, at least to a mapper or map reader. Note that in the USA boundaries are determined by reference to written deeds, and subject to challenge in court. Various non-registered rights, including right of passage, may exist. It's a huge mess. In Australia, as I understand, land ownership is a matter of public record, and all ownership changes must be registered. The government records are, by definition, correct. ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On 03/23/2015 12:29 PM, Bryce Nesbitt wrote: The nice thing about mapping a neighborhood name as a point feature is: a) It helps people locate the neighborhood b) it completely sidesteps the question of the exact, possibly fuzzy, boundaries. For 10% of the hassle you map 90% of the benefit. Or follow the obvious rule: Let the local mappers decide. Use point features for indeterminate things. In areas where neighborhoods have borders that are identifiable on the ground, map the borders. Some neighborhoods are gated. Some are signed. Some, all the locals understand, are bounded by major streets. Many subdivisions, even if not signed, have homogeneous enough architecture that the borders are obvious. And some cities try to foster neighborhood identity and specifically identify neighborhoods, even where the neighborhoods are not legal political entities. Don't decide as an armchair mapper that you know better than the locals. This goes double for using a mechanical edit to fix what the locals have done. Fix only what you can see is wrong on the ground (or what you can't see on the ground at all). This sort of fixing requires boots on the ground. (I'm willing to allow an exception for repairing the damage done by ill-advised mechanical edits - but only after consultation with the locals.) -- 73 de ke9tv/2, Kevin ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
I would politely disagree that TIGER is an authoritative source for two reasons: 1) The extensive TIGER cleanup that is still being done years after the last import, and 2) While helpful at compiling data, the federal government is not authoritative for any boundaries within a state (and once established, not even for the boundaries of the states themselves). -jack On March 24, 2015 4:57:44 PM EDT, Martijn van Exel mart...@openstreetmap.us wrote: there is an authoritative source for official administrative boundaries that can be easily accessed by anyone: TIGER -- Typos courtesy of fancy auto-spell technology. ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On 3/24/15 6:01 PM, Jack Burke wrote: I would politely disagree that TIGER is an authoritative source for two reasons: 1) The extensive TIGER cleanup that is still being done years after the last import, and well, if that data were removed and sourced externally, the problems with TIGER boundary data and OSM would change in character rather substantially. 2) While helpful at compiling data, the federal government is not authoritative for any boundaries within a state (and once established, not even for the boundaries of the states themselves). as part of the ongoing improvements in TIGER, the Census Bureau is increasingly pulling data from County GIS departments rather than maintaining it themselves. the quality is much better. and since it's digital, the game of telephone metaphor does not apply so much any more. richard -- rwe...@averillpark.net Averill Park Networking - GIS IT Consulting OpenStreetMap - PostgreSQL - Linux Java - Web Applications - Search signature.asc Description: OpenPGP digital signature ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Tue, Mar 24, 2015 at 7:46 AM, Kevin Kenny kken...@nycap.rr.com wrote: Or follow the obvious rule: Let the local mappers decide. Use point features for indeterminate things. In areas where neighborhoods have borders that are identifiable on the ground, map the borders. Some neighborhoods are gated. Some are signed. Some, all the locals understand, are bounded by major streets. Many subdivisions, even if not signed, have homogeneous enough architecture that the borders are obvious. And some cities try to foster neighborhood identity and specifically identify neighborhoods, even where the neighborhoods are not legal political entities. Don't decide as an armchair mapper that you know better than the locals. This goes double for using a mechanical edit to fix what the locals have done. Fix only what you can see is wrong on the ground (or what you can't see on the ground at all). This sort of fixing requires boots on the ground. (I'm willing to allow an exception for repairing the damage done by ill-advised mechanical edits - but only after consultation with the locals.) +1 -- @osm_seattle osm_seattle.snowandsnow.us OpenStreetMap: Maps with a human touch ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
I have long been on the fence about boundaries in OSM, and while I don't feel as strongly about it any longer, it still feels wrong to make this sweeping exception to one of the fundamental conventions of OSM mapping: verifiability. For many types of land use, anyone would be able to verify boundaries on the ground: a forest, a corn field, even a retail zone in most cases. But administrative boundaries can only be observed in a limited number of places: wherever there is a sign or a physical boundary in place, and rare other cases. More importantly though, there is an authoritative source for official administrative boundaries that can be easily accessed by anyone: TIGER[1] All of this has little to do with neighborhoods, which are mostly (?) vernacular in naming and delineation, and even when there are official neighborhood designations, in my own experience they do not always match the vernacular names. I support point mapping of vernacular neighborhoods. If you really want to have shapes for vernacular neighborhoods, you can look at the now-ancient-but-still-cool flickr Alpha Shapes[2], last updated in 2011 but still available for download[3]. But please don't upload 'em to OSM :) [1] https://www.census.gov/geo/maps-data/data/tiger-cart-boundary.html [2] http://code.flickr.net/2008/10/30/the-shape-of-alpha/ [3] http://code.flickr.net/2011/01/08/flickr-shapefiles-public-dataset-2-0/ Martijn van Exel Secretary, US Chapter OpenStreetMap http://openstreetmap.us/ http://osm.org/ skype: mvexel On Mon, Mar 23, 2015 at 11:39 AM, Clifford Snow cliff...@snowandsnow.us wrote: On Mon, Mar 23, 2015 at 10:29 AM, Bryce Nesbitt bry...@obviously.com wrote: The nice thing about mapping a neighborhood name as a point feature is: a) It helps people locate the neighborhood b) it completely sidesteps the question of the exact, possibly fuzzy, boundaries. For 10% of the hassle you map 90% of the benefit. Except when it reports you are in a different neighborhood than you actually are. When neighborhoods are not clearly defined then yes, a point is the best choice. But when neighborhoods have defined boundaries then they should be added. Just going up the admin level to city level, points work until it says you are in a different city. We can not see city boundaries but OSM has thousands of city boundaries. The simple solution is if the neighborhood boundaries are clearly defined they belong in OSM as polygons. If neighborhood boundaries are not clearly defined then they should be represented by points. For the supporters of no admin boundaries in OSM, build the case on the mailing lists instead of just saying there is a growing support for no boundaries. In some parts of the US there is a growing support that climate change is a hoax. That doesn't make it true. Build a case for removing admin boundaries (and please include landuse.) Ideally in the future we can have a fuzzy boundary. But until then I think what I proposed is an acceptable solution. Clifford -- @osm_seattle osm_seattle.snowandsnow.us OpenStreetMap: Maps with a human touch ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
Greg, 3. It is my belief and experience that the ground observable rule is something that only applies to Europe or older metropolitan areas. I think there's a misunderstanding here. Of course even in European metropolitan areas there will *not* be a sign bearing the name of every stream that you drive across! That doesn't keep Europeans from mapping the stream (the fact that there *is* one is at least observable), or naming it according to common knowledge or whatever the locals will tell you the name is. We usually draw the line when it is about features that cannot be seen on the ground; these should be in OSM only in exceptional cases (for example we do map administrative boundaries and post code areas even if they're invisible; the discussion about how much of a railway must still be there to map it as abandoned is going on elsewhere; the mapping of airways is strongly discouraged; some people map long-distance radio links but that is not likely to catch on). Your remark that OSM is different from the old GIS world with ESRI and $20k GPS receivers is correct, however it is not a suitable basis for reasoning (following the same logical path as you did, I could say they use computers; we are different, so we should not use computers). The ground observable rule kicks in most strongly when there's a dispute. If one mapper happily maps an invisible boundary and another mapper pops up and maps it differently, and they later apply to someone to mediate in their conflict, that third person will ask whether there is any proof for each mapper's version, and if there isn't any because both just map from hearsay, then the feature will have to be tagged as disputed or removed altogether. 9. Taking Serge's example of neighborhood boundaries to the logical conclusion, nothing should be put in OSM because an edit war __could__ ensue. Again, you've misunderstood Serge; because as long as we stick to observable things, the edit war can be resolved by fact-checking. This is what Serge hinted at when he talked about Alice and Bob. Crucially he also mentioned that there's a high risk that if we allow un-substantiated mapping of neighbourhoods, this might be at the expense of the underprivileged who seldom participate in OSM. For some, it might make a very big difference whether their address resolves to neighbourhood A or neighbourhood B if they live just on the border. As long as we're talking facts there's not much that can go wrong - an able-bodied, college-educated caucasian male can trace a stream through the slums from Bing without being in much danger of unwittingly applying prejudice. The same is not true for the same able-bodied, college-educated caucasian male drawing the boundary of the neighbourhood they are unlikely to ever set foot in. There's actually quite a few things apart from neighbourhoods that are not defined. For example here in Germany, if a village can advertise themselves as being in the Black Forest, that's a plus, tourism-wise. But the Black Forest is not a forest where you simply check the treeline; it's a large region with not-really-well-defined boundaries. There's places where 99% of interviewees would says clearly that's in the Black Forest, and places where 99% would say clearly not, but a grey band in between. The kind of area that is labelled with a curved, wide-spaced font on old-school maps. OSM doesn't have a good mechanism to record these; OSM only accepts precise geometries, not fuzzy ones. 7. The ground observable rule is a barrier to new mappers. I helped a new mapper at a Editathon add taco stands. She did everything wrong. I did say no you cannot add that node. We have not gone and surveyed that node exists. I let her add the node with abbreviated street names and all. She was so exited to add here research data to OSM. There's absolutely no problem with adding Taco stands from memory as they are observABLE (even if not observED) and if someone else starts a fuss about the Taco stands, we can just go there and check. People add data from memory all the time, and if it's wrong, it get fixed. But that's not the point when discussing neighbourhood boundaries. I failed to map for months because it sounded like I had to have a GPS five years ago before I could map. I think you're consistently misunderstanding the difference between observable and observed. Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09 E008°23'33 ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
Greg Morgan wrote: 2. To quote Richard Fairhurst, Seriously, OSM in the [England] s still way beyond broken. You can open it at any random location and the map is just __fictional__. Here are two random examples bing;OS StreetView [2] shape is approximate. Needs proper survey as mostly built after current BING imagery date [3] I have no idea, at all, what point you are trying to make, but I would appreciate it if you didn't make it by deliberately misquoting me. Thank you. Richard -- View this message in context: http://gis.19327.n5.nabble.com/Retagging-hamlets-in-the-US-tp5837186p5838190.html Sent from the USA mailing list archive at Nabble.com. ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Mon, Mar 23, 2015 at 2:30 AM, Greg Morgan dr.kludge...@gmail.com wrote: 1. Every time this boundary debate or accuracy debate comes up, I image that I am supposed to have $20,000 of GPS equipment[1]; post process the data so that it is accurate; before I dare put the data in OSM. I agree with you that things which you can't verfiy without thousands of dollars of equipment doesn't belong in a generalized dataset like OSM. 3. It is my belief and experience that the ground observable rule is something that only applies to Europe or older metropolitan areas. Then you're going to have problems with all of OSM, since we use that rule to handle virtually any dispute. I am curios what river or wash I just drove over. It is not posted. I had to go to the US government sites to find the information because it is useful in OSM. It's entirely possible that the names the locals use for that river differ from the government dataset, in which case, OSM would prefer you use the local name as the primary name, and not the official one. Ground observable in this case is Local knowledge. Of course that requires consensus, but this is why we have so many tags related to names 6. The ground observable rule is trying to take over the more important rule: Mappers with local knowledge of their area add valuable data that commercial mapping companies cannot always afford to add to the map. This is based on a misunderstanding of your understanding of what the ground observable rule is. A person who lives in an area and can talk about it will actually trump most other sources, including signage, but that requires that we get lots of people involved and working in a diplomatic way. 7. The ground observable rule is a barrier to new mappers. I helped a new mapper at a Editathon add taco stands. She did everything wrong. I did say no you cannot add that node. We have not gone and surveyed that node exists. I let her add the node with abbreviated street names and all. She was so exited to add here research data to OSM. Why not help her ensure that her data be in OSM by being a teaching resource? Also, what does sign names have to do with ground surveying? 8. The ground observable rule is a barrier to new mappers. Most of the new mappers I know started mapping by signing up and adding data. Adding data they surveyed or adding data they got from another source? 9. Taking Serge's example of neighborhood boundaries to the logical conclusion, nothing should be put in OSM because an edit war __could__ ensue. This is quite the stawman argument you've build in my name, but it's not my argument. OSM has a long history of encouraging surveyed data. 11. The ground observable rule fails to acknowledge that not every feature is observable but still is useful to OSM. I had to talk the rent-a-cops out of arresting me for taking pictures around Chase Field [8]. I could not see around the building or under the 7th street bridge via satellite imagery. In this post 911 world, the ground observable rule is an unrealistic requirement. I've never encountered a problem with law enforcement officials when mapping, so I can't speak to your experience. 12.I am passionate about what I do with OSM and the out reach that I do. I am game to survey and map my city, county, and state. It feels like this growing number of people believes that every mapper has to map just like Steve Coast did ten years ago. Congratulations Serge! It is my growing belief that your growing number of people has stymied growth in new and different valuable ways of mapping data. I failed to map for months because it sounded like I had to have a GPS five years ago before I could map. Last year (or was it the year before) at SOTM US, there was discussed with Ian Dees leading the discussion about using municipal data in a separate dataset, and yet I don't see you being as viscous against him. Whether it's deliberate or not, please stop misquoting me to further your arguments. - Serge ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
I agree 100% with Bryce. - Serge On Mon, Mar 23, 2015 at 12:29 PM, Bryce Nesbitt bry...@obviously.com wrote: The nice thing about mapping a neighborhood name as a point feature is: a) It helps people locate the neighborhood b) it completely sidesteps the question of the exact, possibly fuzzy, boundaries. For 10% of the hassle you map 90% of the benefit. ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Sun, Mar 22, 2015 at 2:04 PM, Minh Nguyen m...@nguyen.cincinnati.oh.us wrote: tl;dr: I'm against a blanket rule when it comes to administrative boundaries. They're really nuanced, and so should we. On 2015-03-22 04:32, Serge Wroclawski wrote: Imagine if Bob and Alice conflict on where a neighborhood boundary is inside OSM. The issue escalates to an edit war and the DWG is called in to resolve the conflict. Let's say that Frank is our DWG member. How is Frank supposed to resolve the conflict between Alice and Bob? Often neighborhoods don't have administrative recognition, or administrative recognition is not in alignment with the people. I imagine this would be especially an issue with neighborhoods where lots of the under-represented populations live. This is an important consideration. As I mentioned in a footnote earlier, even a city with strong neighborhood organization can have boundary disputes. However, the problem exists for administrative boundaries in general, all the way up to admin_level=2 boundaries that cut right across ethnic fault lines. My point was that we should map neighborhood boundaries in cities where doing so requires little editorial judgment, thanks to signage, distinctive lamp posts, etc. And we are quite clear (via the tag value administrative) that this isn't the only way by which a community can be delimited. As numerous threads have pointed out, the USPS has very different ideas of location (ZIP codes), but that's OK. When it comes to all our discussions around *administrative* boundaries, I like this two-point test as a rule of thumb: 1. Are people or property governed differently on one side versus the other? 2. Is this distinction observable on the ground? Municipalities generally pass both points. Congressional districts pass #1 but not #2. CDPs generally fail both. School districts can be observed, but not with the granularity required for mapping a boundary. City neighborhoods may pass one, both, or neither. Maybe all the locals you interview can agree on the name of a neighborhood but not its shape -- in which case it should be nothing more than a POI. Which brings me to Serge's other point: First, there are a growing number of people who believe that administrative data is very useful, but breaks OSM's ground observable rule. That is, someone who is present on the ground should be able to observe the data in OSM. It's usually not possible to do that with administrative boundaries. SteveA has responded more forcefully on this point, and so have I in the past. [1] Fortunately, Alice and Bob's disagreement sounds pretty clear-cut. If the city didn't go through the trouble of demarcating any part of the boundary in some way, perhaps the general public shouldn't expect OSM to reproduce their two neighborhoods' boundaries at all. But I see no reason why such a decision would impact boundaries with very different characteristics. tl;dr: I'm against blanket rules especially when they don't reflect the realities of the world or how far we have come in ten years. These rules prevent progress and new ways of thinking about solutions. Imagine the changes OSM, OpenLayers, Leafet, MapBox have made. The ESRI rule said that we shouldn't do it that way. You should spend large amounts of money to do GIS things. Based on my ESRI analogy, the ground observable rule feels like using ArcGIS Desktop to do mapping. Is that a reality anymore? In actuality, the OSM and ESRI way complement each other and can be used together. 1. Every time this boundary debate or accuracy debate comes up, I image that I am supposed to have $20,000 of GPS equipment[1]; post process the data so that it is accurate; before I dare put the data in OSM. 2. To quote Richard Fairhurst, Seriously, OSM in the [England] s still way beyond broken. You can open it at any random location and the map is just __fictional__. Here are two random examples bing;OS StreetView [2] shape is approximate. Needs proper survey as mostly built after current BING imagery date [3] I thought Bing was so bad that it is broken. What is happening with this growing number of people is they say or imply that England, the birth place of OSM, is the bee's knees for accuracy because it was surveyed the old fashioned way. I find no difference in these two examples in England than adding an approximate area in the US based on a subdivision or some other locally named area. 3. It is my belief and experience that the ground observable rule is something that only applies to Europe or older metropolitan areas. There's a number of times that I have read on the US list that either the signs are missing, stolen, or never posted. One of the reasons I map what I do is because the signs are missing. I am curios what river or wash I just drove over. It is not posted. I had to go to the US government sites to find the information because it is useful in OSM. So what do you want
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
The nice thing about mapping a neighborhood name as a point feature is: a) It helps people locate the neighborhood b) it completely sidesteps the question of the exact, possibly fuzzy, boundaries. For 10% of the hassle you map 90% of the benefit. ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Mon, Mar 23, 2015 at 10:29 AM, Bryce Nesbitt bry...@obviously.com wrote: The nice thing about mapping a neighborhood name as a point feature is: a) It helps people locate the neighborhood b) it completely sidesteps the question of the exact, possibly fuzzy, boundaries. For 10% of the hassle you map 90% of the benefit. Except when it reports you are in a different neighborhood than you actually are. When neighborhoods are not clearly defined then yes, a point is the best choice. But when neighborhoods have defined boundaries then they should be added. Just going up the admin level to city level, points work until it says you are in a different city. We can not see city boundaries but OSM has thousands of city boundaries. The simple solution is if the neighborhood boundaries are clearly defined they belong in OSM as polygons. If neighborhood boundaries are not clearly defined then they should be represented by points. For the supporters of no admin boundaries in OSM, build the case on the mailing lists instead of just saying there is a growing support for no boundaries. In some parts of the US there is a growing support that climate change is a hoax. That doesn't make it true. Build a case for removing admin boundaries (and please include landuse.) Ideally in the future we can have a fuzzy boundary. But until then I think what I proposed is an acceptable solution. Clifford -- @osm_seattle osm_seattle.snowandsnow.us OpenStreetMap: Maps with a human touch ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
Re: [Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
On Mon, Mar 23, 2015 at 10:39 AM, Clifford Snow cliff...@snowandsnow.us wrote: Except when it reports you are in a different neighborhood than you actually are. A point feature does not imply a radius. A governmental defined neighborhood boundary is totally mappable at the right admin level, and you would not need point features in such a case. ___ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
[Talk-us] Boundaries and verifiability (was Re: Retagging hamlets in the US)
tl;dr: I'm against a blanket rule when it comes to administrative boundaries. They're really nuanced, and so should we. On 2015-03-22 04:32, Serge Wroclawski wrote: Imagine if Bob and Alice conflict on where a neighborhood boundary is inside OSM. The issue escalates to an edit war and the DWG is called in to resolve the conflict. Let's say that Frank is our DWG member. How is Frank supposed to resolve the conflict between Alice and Bob? Often neighborhoods don't have administrative recognition, or administrative recognition is not in alignment with the people. I imagine this would be especially an issue with neighborhoods where lots of the under-represented populations live. This is an important consideration. As I mentioned in a footnote earlier, even a city with strong neighborhood organization can have boundary disputes. However, the problem exists for administrative boundaries in general, all the way up to admin_level=2 boundaries that cut right across ethnic fault lines. My point was that we should map neighborhood boundaries in cities where doing so requires little editorial judgment, thanks to signage, distinctive lamp posts, etc. And we are quite clear (via the tag value administrative) that this isn't the only way by which a community can be delimited. As numerous threads have pointed out, the USPS has very different ideas of location (ZIP codes), but that's OK. When it comes to all our discussions around *administrative* boundaries, I like this two-point test as a rule of thumb: 1. Are people or property governed differently on one side versus the other? 2. Is this distinction observable on the ground? Municipalities generally pass both points. Congressional districts pass #1 but not #2. CDPs generally fail both. School districts can be observed, but not with the granularity required for mapping a boundary. City neighborhoods may pass one, both, or neither. Maybe all the locals you interview can agree on the name of a neighborhood but not its shape -- in which case it should be nothing more than a POI. Which brings me to Serge's other point: First, there are a growing number of people who believe that administrative data is very useful, but breaks OSM's ground observable rule. That is, someone who is present on the ground should be able to observe the data in OSM. It's usually not possible to do that with administrative boundaries. SteveA has responded more forcefully on this point, and so have I in the past. [1] Fortunately, Alice and Bob's disagreement sounds pretty clear-cut. If the city didn't go through the trouble of demarcating any part of the boundary in some way, perhaps the general public shouldn't expect OSM to reproduce their two neighborhoods' boundaries at all. But I see no reason why such a decision would impact boundaries with very different characteristics. -*-*-*- Serge's focus on verifiability relates to a boundary I've spent a lot of time on lately, so I'm going to go way over my word limit. Last month, I reminded this list that state borders along the Ohio River actually follow the river's historical northern bank, not its present-day thalweg or centerline. [2] Even if you send a diver into the river, there isn't always going to be a natural feature to verify OSM data against. We have a few options: 1. Try to be as accurate as possible by tracing USGS topo maps. Treat these borders as a practical exception to the on-the-ground rule. Use the source tag rigorously. 2a. Conflate the state borders with the current thalweg. We'd give Ohio and Indiana various islands and dams that actually belong to Kentucky and West Virginia, ignoring the Supreme Court ruling. We'd be putting intentionally inaccurate data into OSM. 2b. Conflate the state borders with the current northern bank, siding with Kentucky and again ignoring the Supreme Court ruling. We'd give the entire river to Kentucky and West Virginia, including riverboat casinos that keep to the Indiana side but are illegal in Kentucky. 3. Omit the river boundaries but leave the rest of the state lines intact. This approach introduces technical problems like broken multipolygon relations and just confuses people. Where does West Virginia end? 4. Omit the entire boundaries of states that border the Ohio River. It'll look like a mistake, so people will helpfully and sloppily add the boundaries back in. 5. Omit all state lines, everywhere, throwing away lots and lots of fixup work done with care by volunteer mappers. And all because Kentucky wanted the whole river. Everyone agrees the river is the boundary, just not what the river means. In this case, I say we hold our noses and go with #1 as the most accurate, least disruptive approach. [3] [1] https://lists.openstreetmap.org/pipermail/talk-us/2013-January/010162.html [2] https://lists.openstreetmap.org/pipermail/talk-us/2015-February/014307.html [3]
