Re: [Tagging] coastline v. water
Hi, Recently, Chesapeake Bay (the largest estuary in the United States with a surface area of over 10,000 sqkm) has been changed from "natural=coastline" tagging to form a large "natural=water;water=lagoon" multipolygon instead. The area has also been split into the bay itself, the Pocomore Sound, the Tangier Sound, and other smaller bodies. Current coastline:https://overpass-turbo.eu/s/10xZ (zoom in or out and re-query as desired). Previous coastline as of 2020-06-01:https://overpass-turbo.eu/s/10y1 (again, zoom in or out and rerun the query). As a consequence, the world-wide coastline processing is stuck. Discussions have happened here on this list, as well as on talk-us and on the changeset itself:https://www.openstreetmap.org/changeset/94093155 Among the reasons for this change, the following have been mentioned: * polygon allows better labelling * polygon allows better geocoding for points on bay water surface * bay is not really "sea" hence coastline is incorrect * natural=water tagging allows for quicker turnaround times to see your edits on the map * local mappers should decide how they want stuff tagged Opponents of the change have said, among other things: * natural=coastline does not mean "literal" coastline * a major change like this should be discussed thoroughly before executing * large polygon hampers editing+QA * boundaries between water polygons, or between water polygons and sea, are arbitrary and not verifiable The possible solutions to this issue are: * accept current situation as correct and resume world-wide coastline processing based on this as a new "known good" state * revert the change wholesale and request prior discussion and consensus in the community * any mixture of the above Following internal discussion within the DWG, we propose the following: * the polygons that have been created will not be removed * the land-side members of the polygons for Chesapeake Bay, Tangier Sound, Pocomore Sound and potentially others that have been created as part of this operation will be given back their natural=coastline tags In addition, currentlyhttps://www.openstreetmap.org/relation/11884052 is mapped as "natural=water; water=lagoon" which does not match the wiki definition athttps://wiki.openstreetmap.org/wiki/Tag:water=lagoon . Perhapshttps://wiki.openstreetmap.org/wiki/Tag:natural%3Dbay would be a better tag? This is of course an entirely separate discussion to where the OSM concept "natural=coastline" should go - we don't propose to change the tagging on relation 11884052 now but it probably does need looking at. This is not intended as a definitive solution for all times, just as a stop-gap measure until a consensus is found and, once it has, tools have been amended where necessary. Future community discussion may still lead to the removal of the coastline tagging, or to the removal of the polygons and their replacement by a label point. For now we're just trying to get to a place where other people around the world can make valid coastline edits and see their changes go live. The current impasse over Chesapeake Bay is currently stopping that. Are the local mappers willing to help implement this? If not, the DWG will do it so that normal coastline processing elsewhere can resume. We apologise in advance to anyone who thinks that this is an incorrect decision, but unfortunately sometimes a decision between one of two outcomes (neither of which is universally popular) has to be made. In such cases the DWG often reverts to the "status quo ante", and we think that makes sense here too. Best Regards, Andy Townsend, on behalf of the Data Working Group On 18/11/2020 20:19, Eric H. Christensen via Tagging wrote: After a few days of much work, a recent collaborative project to turn the Chesapeake Bay from a nothing space outlined by natural=coastline to what we considered to be a more accurate relation of natural=water, we've received some negative feedback. The difference of opinion seems to lie in the definition of what we're mapping. The use of coastline is for "seas"[0] while the use of water is for "inland areas of water"[1]. Even though the Chesapeake Bay is tidal, there is no question that it is an inland waterway (it is completely surrounded by land except for the mouth at its southeast side). The idea of using coastlines for basically creating an edge between the land and the nothingness of the ocean makes sense when, as far as the eye can see it's only water. Now, some of the feedback that has been presented[2] is that because it is tidal it is part of the sea. I have pointed out that many rivers and streams (and ditches!) are tidal; does that make them part of the sea? I would not think so. In fact, there are named seas on this planet that are not even connected to other water formations (the tiniest, according to the National Geographic, is the Sea of Marmara which has an area just less than 12,950 s
Re: [Tagging] coastline v. water
By the way, an... amusing test case for all things related to water and label placement is Lake Mälaren, the lake that Stockholm is separating from the sea, and all its (named!) nooks and crannies: https://www.openstreetmap.org/relation/1433877 . I've had at least 3 different bits of it poking into different corners of the map at times. ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
On Wed, 25 Nov 2020 at 08:45, Ture Pålsson via Tagging < tagging@openstreetmap.org> wrote: > > (And I agree with Kevin about reconstructing an area from a point + > surrounding coastline. I'd like to see at least an outline of an > algorithm for that! Having said that, I also recognise that > gazillion-point polygons to outline Skagerrak, Kattegatt, the North Sea > and what-have-you may not be the prettiest state of things either...) > I'm not convinced that point + coastline will give a reasonable result enough of the time. But I could be wrong about that. Polygons that are contiguous with the coastline are a pain to add, even with generalized coastline (and even worse if Slartibartfast has added crinkly bits to the coastline). It's a lot of work. If the polygon is crude and not contiguous with the coastline that can give bogus results when trying to determine if a given co-ordinate is in a named bay or not. However, it is often the case that the ends of bays are known (local knowledge that village X is in Y bay) or are obvious from inspection. Since at least one person is confident that a single point is enough to create a workable algorithm, two points should be twice as good! Yeah, I was joking, but a lot less code and a lot less algorithmic guesswork would be involved in marking two points on a coastline that define the extent of the bay. An algorithm can generate a bounding polygon from those two points, the coastline between them, and a straight line connecting them. The hardest part would be ensuring that the algorithm takes the shortest segment of coastline between the two points and not the longest segment. Better than two points would be a way joining those two points. In the absence of further knowledge, map a simple straight line. A straight line is an approximation because currents and water depths might mean hydrographers and/or mariners regard the seaward extent of the bay to be wibbly-wobbly (one of the examples posted on the list showed a convex seaward extent of a bay). So use a way rather than two points to allow for curvy seaward extents, where known. Using a way rather than a polygon avoids the problems of nested bays. There are many small bays within Cardigan Bay (mapped by somebody as a polygon): https://www.openstreetmap.org/way/651881240 It would also deal with the potential problem of overlapping bays (imperfect nesting), should that ever be necessary, without mappers having to jump through hoops constructed of multipolygons. As far as I can see we can use a point, placed by visual inspection, and add a tag for importance which determines (in cartos that make use of it) the size of the label and at what zooms the label appears. Or we use a way to determine closure of the bay and let an algorithm handle placement and importance of the label. An algorithm would give greater consistency than mappers using their best guess at how important the label should be. Yes, the way could be abused by people wanting to control placement of the label. As could the point. As could any other way of mapping bays that we come up with. I don't think we should reject solutions because somebody could abuse them, otherwise we wouldn't have any tags at all. -- Paul ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
I mentioned the problem of mapping "fuzzy" areas to a friend, who replied along the lines of "why, of course such areas should be mapped as functions, taking a point as input and returning a real between 0 (definitely outside) and 1 (definitely inside)!". I'd rather not have to implement that, though. =) (And I agree with Kevin about reconstructing an area from a point + surrounding coastline. I'd like to see at least an outline of an algorithm for that! Having said that, I also recognise that gazillion-point polygons to outline Skagerrak, Kattegatt, the North Sea and what-have-you may not be the prettiest state of things either...) ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
On Tue, Nov 24, 2020 at 9:23 AM Christoph Hormann wrote: > The problem we have here is that of a widening gap between the goals and > aspirations of the mapper community - which naturally grow as OSM grows in > ambitions - and the abilities and engagement in the non-mapping part of the > community to develop and satisfy similar ambitions in cartographic quality > without outsourcing the hard part of that work to the mappers. Too many > people have followed the illusion for too long that the large corporate OSM > data users will provide the necessary support in that field while it turns > out (non-surprisingly in my eyes) that they have neither an interest in > above average cartographic quality nor in substantially sharing methods and > competency in the little work they do in that domain. > (Brief summary: 1. Many area features are indefinite only at margins that do not have a significant deleterious effect on statistics when analyzed or on the understanding of the map when rendered. 2. Topology still matters - for analyzing or rendering them. 3. Algorithm development needs data to chew on. Blocking the data while waiting for the algorithms is a 'deadly embrace.' 4. Mappers are continuing to enter the data for approximate regions because they understand 1.-3. above. 5. Which argument are you willing to give up in order not to argue against all progress in this domain?) In my earlier message, I was speaking not as a mapper looking to enter data, nor as a map user looking for a pretty rendering - although I wear both those hats from time to time - but as a newly-retired applied mathematician (A.B., mathematics, Dartmouth College, MS in electrical engineering, Arizona State University, PhD, computer science, University of Illinois, about forty years of experience with GE, Northrop, Honeywell, and others), with a reasonable background in computational geometry, thinking of what challenges I ought to tackle next. Given that one of my principal avocations is hiking, my chief rendering interest is not with an endlessly-panning map, as useful as that is; it is with paper maps where labeling must conform with the neatline. For those maps, simply placing a point for 'label painting' near the center of an indefinite feature is not sufficient. Instead, a first step has to be calculating the intersection of the area feature with the region of interest, leading to one of the results: (a) the area is totally within the region; (b) the area is totally outside the region and may be discarded; (c) the area intersects the region partially and one or more regions of intersection must have labels placed individually. The 'one or more' arises from the fact that a non-convex area feature or a non-convex region of interest (a rectangle, for instance, with a corner cut out for placement of a legend) may yield more than one polygon of intersection. You have on several occasions advanced the argument that the central label should be enough for this and made a contention that I don't understand about projecting from the central label of a bay onto the shoreline to reconstruct the area. With that contention came the implication that the topological information about an indefinite area would not be needed, if only the renderers and data analysts worked hard enough. Unless you can provide me with literature citations to what you have in mind, I'm afraid that I'll have to dismiss your claim as hand-waving. As far as I can tell, there is no known way to achieve the result that mappers want - or at least I want - without the detailed geometry of the partially indefinite area. If you can provide such citations, I'm eager to follow up with you! I should digress into the phrase, 'partially indefinite,' that I've already been using. For the contentious areas such as the Red Sea, the indefinite portion about which the controversy arises is typically small, and typically of a nature where a rough approximation is acceptable to all users. There is no controversy arising from the shoreline of the Red Sea except for a trivial amount of border. Very few claim that the Red Sea exists only as a social construct. Scientists discuss its hydrology and ecology in contradistinction to that of the region of the Indian Ocean to which it connects. Mariners speak of Port Sudan, Jeddah, Sharm al-Sheikh, or Eilat as Red Sea ports (Eilat may be further specialised as being a port on the Gulf of Aqaba, a smaller area that is similarly well-defined; the relation is one of hierarchy rather than exclusion. (Moving somewhat to the northwest, I've seen papers on hydrology that have tabulated observations in rows labeled 'Ionian Sea', 'Ægean Sea', 'Tyrrhenian Sea', 'Adriatic Sea', and so on. There is _some_ shared understanding that those words have meanings.) 'Partially indefinite' extends to other features such as peninsulæ (a mirror image of bays - the indefinite boundary is one of land rather than water); straits (indefinite water margins at both ends)
Re: [Tagging] coastline v. water
> there were some attempts to suggest universally mapping bays with polygons > rather than nodes previously: > > > https://lists.openstreetmap.org/pipermail/tagging/2014-October/thread.html#19775 > > which however never reached consensus because of the weighty arguments > against this idea and because it was always clear that this would be a > non-sustainable strategy for OSM in the long term. > It seems to me that consensus is achieved via three, often overlapping methods, in no particular order: 1. The proposal process 2. What's documented on the wiki 3. How tagging is actually used by mappers and data consumers Specific discussions on the tagging lists are not necessarily good indicators of consensus because they are often dominated by whomever happens to be shouting the loudest and subscribed to the tagging list at that moment. With regard to mapping named bodies of water, possibly with fuzzy boundaries, using polygons, the wiki documents that this is an acceptable practice, as long as those polygons aren't too large (though, unhelpfully, without defining what "too large" means). As you note, osm-carto supports this method of tagging for marginal seas, and mappers have adopted such tagging. Thus, by wiki, and by actual tagging, and by data consumer usage, there IS consensus - it is acceptable but not required to tag such things as polygons. We should not expect mappers to read the minds of people that are subscribed to this list or comb through years of mailing list archives to understand how tagging standards have evolved. The history of how we got here is irrelevant -- what matters is what exists now, what problems it may or may not be causing, and what to do about it going forward. Since you note that there is not a technical limitation, the argument seems to boil down to "I don't like the standard of verifiability that other mappers are using." That is a perfectly valid opinion to have, but it does not trump de facto, documented usage. Given the community acceptance of polygon mapping for smaller marginal seas, it would seem that a formal proposal is the minimum standard required for documenting that there is consensus to change de facto usage. If this is a truly bad idea, and the arguments against such mapping are so strong, it should be a no-brainer to draft a proposal laying out such arguments so that the broader community can consider them and demonstrate true consensus. ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
There seems to be quite a lot of anger and animosity in here - paired and in parts probably caused by a very selective and in parts flat out wrong perception of history so i will try to sketch quickly how the development of mapping of names of parts of waterbodies (that is mostly bays and straits) in OSM developed historically. For a long time - until a few years back - these features were overwhelmingly mapped with nodes. This was consensus, not because of technical constraints disallowing something else, but because of the realization that in the vast majority of cases this is perfectly sufficient to document all verifiable information available about the feature in question. Practically in 2016 there were about 5 percent of all bay features mapped with polygons: https://github.com/gravitystorm/openstreetmap-carto/issues/2068#issuecomment-191677580 which - generously estimated - probably matches about the percentage of cases where you could argue that with a polygon you could record some verifiable information that cannot recorded with a node or a linear way (which still does not mean the polygon is a good data model for such features, just that it has in those cases - besides all disadvantages - also some advantages over a node or a linear way). This situation was relatively stable - there were some attempts to suggest universally mapping bays with polygons rather than nodes previously: https://lists.openstreetmap.org/pipermail/tagging/2014-October/thread.html#19775 which however never reached consensus because of the weighty arguments against this idea and because it was always clear that this would be a non-sustainable strategy for OSM in the long term. Until early 2018 when OSM-Carto (where merging changes was at that time possible without consensus) added rendering of labels for bay polygons with label size and starting zoom level being determined by the size of the polygon but otherwise with no visual feedback or consideration for the geometry of the polygon: https://github.com/gravitystorm/openstreetmap-carto/pull/3144 - dismissing warnings about the counterproductive incentives this creates: https://github.com/gravitystorm/openstreetmap-carto/issues/2068#issuecomment-191677580 This lead to a massive change in mapping activities with some mappers engaging in systematic endeavors of removing bay nodes and drawing labeling polygons instead. You can probably say this was by far the most successful attempt at steering mappers into a certain direction ever undertaken by OSM-Carto. While the relative number of bay polygons compared to nodes only increased from about 5 to 15 percent while very few bays were actually newly mapped the total surface area of bay polygons probably increased by a factor of 100-1000 - many of them evidently pure labeling geometries. See https://www.openstreetmap.org/user/imagico/diary/47432 for some examples. This has lead to some mappers removing such label geometry drawings as non-verifiable and pointless (like the mentioned Gulf of Bothnia) - though practically none of these attempts could make a dent against the massive labeling polygon drawing trends. What does this have to do with technical limitations or constraints? Very little. Technical limitations and performance constraints in rendering have never been a factor speaking against drawing large and non-verifiable labeling polygons. OSM-Carto and countless other map styles have for many years labeled huge administrative boundary relations without issues and this is not any more difficult for bay polygons. And if it was an issue the solution would be rather simple: Precalculating ST_PointOnSurface() on import in osm2pgsql. The argument against drawing bay and strait polygons is one of practical verifiability and maintainability for the mapper. This is not a technical issue, this is a social issue. Now i completely get the frustration of both mappers and map producers here. Mappers want their mapping to be shown in good quality in maps and if the only way to achieve that is to draw non-verifiable labeling geometries they are willing to invest significant time and energy into that and rationalize that in various ways. And for map producers with a rudimentary GIS data analyst background and experience mostly in more or less atomic processing of point, linestring and polygon geometries and their spatial relationships but no deeper background in cartographic data processing specifically, the task of producing high quality labeling from bay nodes and a flat set of coastline ways or the osmcoastline output is a steep hurdle. And in conventional digital map production from dedicated cartographic databases (in contrast to OSM with its generic geodatabase scope) labeling polygons is the state of the art to manage labeling of course. The problem we have here is that of a widening gap between the goals and aspirations of the mapper community - whi
Re: [Tagging] coastline v. water
On Mon, Nov 23, 2020 at 2:57 PM Frederik Ramm wrote: > Now, you might smirk and say "let's fix the tools then", but until the > tools are fixed - which might take years -, you've made life a hell of a > lot harder for anyone editing or quality monitoring in the whole area. > > And all for what - a nice blue label in the bay? > TL;DR: I understand the technical problems. Don't let the technical problems block the discussion for people who might be able to develop technical solutions. Back when this discussion started, it started because you deleted a relation for the Gulf of Bothnia, entirely without warning, without discussion, and without mentioning it in public even afterward until it was noticed and you were called on it in public. Generally speaking, it was accepted, ex post facto, as an emergency measure needed to rescue the servers from a performance trap, and most of us were willing to accept a temporary moratorium on creating large area relations because of the technical complications. That issue became complicated because others chimed in and started to argue that, rather than being a measure to rescue the servers from trouble, it was actually a reflection of a universally accepted policy that every millimetre of an area feature's boundary must be unambiguously defined and visible on the ground, and the discussion rapidly deteriorated because that definition, taken to its logical extreme, would exclude virtually all rivers, lakes and streams from being distinct bodies of water, would entirely exclude features such as bays, isthmi, peninsulae, and so on from ever being mapped regardless of size or obvious closure, and in general would dismiss topology as being entirely unimportant. The arguments went as far as to have one user advance the claim that a number of counties and townships north of me should not be mapped, despite having well-defined borders in the inhabited regions, because portions of their boundaries have never been successfully surveyed. But somehow, those voices never gained entirely the upper hand. If so, features like `bay`, `peninsula`, `strait`, `isthmus`, `ridge`, `valley` and so on would all bear prominent warnings on the Wiki that it is inappropriate to map them. Somehow, the people who loudly proclaim that objectivity and observability require that every feature be bright-line observable in the field cannot bring themselves to do that, or know that the community would reject it. For myself, I've deferred to you on the matter - including refraining from mapping even small features like Jamaica Bay ( https://www.openstreetmap.org/#map=12/40.6125/-73.8082) - despite the fact that the specific feature is reasonably sized, local, quite different from the Atlantic Ocean (calm water, much lower salinity, much greater tidal range, and a very different ecosystem) and that I would very much like at some point to produce a detailed paper map of my boyhood home town ( https://www.openstreetmap.org/relation/174930) including, of course, labeling the waterways that lie only partially within its neatline. I'm willing to accept for now that OSM cannot cope with that requirement and I'll have to develop another system alongside OSM and manage multiple map layers to produce such a thing. That sort of desire - wishing to include some information about long routes or about area features that are large, diffuse, imprecisely defined, or otherwise difficult - appears to be fairly commonplace, given the number of words that have been expended on the subject here and elsewhere. Those of us to whom the topology of area features is important - for instance, because we produce paper maps and wish to produce normal rendering, including labeling, of area features that extend outside the neatline - rapidly grew frustrated, and eventually the discussion died from exhaustion, as discussions on this list usually do. Meanwhile, there's no indication to mappers (for example, warnings in the popular editors) that creating enormous area features is inappropriate because of inability of the tools to deal with them. Moreover, those who actually have the technical expertise to experiment with solutions to the problem feel stymied at every turn by the gatekeepers - who may also have the technical expertise, but have a different opinion of the problem's importance. I've talked off-list with several skilled programmers and data analysts who definitely believe that even if a solution were to be developed, it would be rejected. There is certainly zero interest from the gatekeepers in maintaining a discussion of the requirements for such a thing - it turns into 'I haven't seen a good enough solution yet, and I'll know it when I see it,' without an answer to, 'in what way is a given proposal unsatisfactory and how might it improve?' There's a natural temptation to transform, 'this problem is too hard for me to solve in the time I have available' into 'this problem is too hard in relation to its importance', to
Re: [Tagging] coastline v. water
Hi, I would like to make one point that has been touched on but not said clearly, I think. Some proponents of the recent changes to Chesapeake bay have used reasoning like: "Only by mapping the bay as a polygon can $SOFTWARE properly determine that a given location is in the bay, as opposed to in some undfined part of the sea." To this, Jochen has even replied along the lines of "create a polygon if you want but additionally use the natural=coastline tag". I want to issue a stern warning here: This line of thinking will not stop with Chesapeake bay. People are already creating giant multipolygons for the Strait of X and the Gulf of Y all over OSM. Before too long, a desire to have $SOFTWARE properly decide that a given location is, say, in the Atlantic Ocean, will give rise to demands that the Atlantic Ocean be mapped as a giant, named water polygon. Our current tooling makes this impractical (that's the very reason why we handle the coastline like we do). Even the 2000+ member "gulfs" and "bays" and "straits" that some people seem to derive endless pleasure from plastering the map with - often using questionable third-party sources or guesswork to define where exactly you leave the ocean and enter the gulf - already complicate the delicate community processes of editing and quality assurance. Splitting a single piece of coastline anywhere along Chesapeake bay now will, for example, give your changeset a bounding box that encompasses the whole bay. Anyone monitoring local edits gets swamped with false positives like that. It will also require uploading a complete new version of the giant bay polygon, vastly increasing the likelihood of edit conflicts that might well lead a hapless novice to abandoning their work, rather than trying to solve the conflict. Now, you might smirk and say "let's fix the tools then", but until the tools are fixed - which might take years -, you've made life a hell of a lot harder for anyone editing or quality monitoring in the whole area. And all for what - a nice blue label in the bay? Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
I've spent a significant amount of time painstakingly re-mapping the crudely-drawn PGS coastal boundaries of Rhode Island to conform to the wiki definition of natural=coastline, having it traverse all the little bays, coves, inlets, etc. I've also been adding named bodies of water as polygons outside of the coastline ways as these two techniques can coexist just fine. I would be quite upset if another mapper came along and undid all that work because they didn't like the documented definition and chose to arbitrarily apply a different one. On Sun, Nov 22, 2020, 3:41 AM Sarah Hoffmann wrote: > Hi, > > On Sat, Nov 21, 2020 at 07:09:45PM +, Eric H. Christensen via Tagging > wrote: > > You cannot point to other area that may, in fact, be improperly mapped > as an example when they are like that because locals have been shouted down > for doing it correctly. The fact that this keeps coming back up literally > means that there is not universal agreement that "marginal seas", whatever > that means, are to be mapped with natural=coastline. > > > > The Chesapeake Bay is an estuary that, by definition, opens to the sea. > It can't be a sea and open to a sea at the same time. In this environment, > it is different from the ocean in which it opens into and is also different > from the tributaries that feed it. These are protected waters for ships. > You won't find any high seas forecasts for the Bay unlike the ocean. The > Bay is also brackish and not defined as salt water, unlike the ocean. > > There is a very fundamental misunderstanding on how OpenStreetMap works > in here. The definition of a tag comes from the agreed-on understanding > of the OpenStreetMap community as a whole of what that tag should be. This > may or may not agree with defintion of the same word in other contexts. > That's just the way it is with defintions. They may differ. You cannot just > uniterally apply a definition of coastline that you think is more > appropriate, or scientifically correct or whatever and change the map. > It is OSM's definition that counts, and OSM's defintion only. > > That doesn't mean that definitions can't evolve over time but that needs > to be discussed when it has a larger impact. natural=coastline > is a particular touchy tag here because it is one of the few tags where > we rely on a agreed-on definition that works on a planet-scale. Even if > you change something relatively locally, it has an effect on how the > planet map as a whole is rendered. You can't just apply a new definition > to one bay. We must agree on a new definition globally here and apply it > globally or the tagging becomes a worthless mess. > > So please, by all means, start a discussion about a new definition of > coastline, make a wiki page, put it up for voting. But all this should > be done **before** making any larger changes. For now, please, put > the Chesapeake Bay back into its original state. > > Kind regards > > Sarah > > > ‐‐‐ Original Message ‐‐‐ > > On Saturday, November 21, 2020 1:14 PM, Joseph Eisenberg < > joseph.eisenb...@gmail.com> wrote: > > > > > Eric, > > > I don't think the previous discussion is quite as inconclusive as your > evaluation. > > > > > > While it is true that there is not widespread agreement on where the > natural=coatline ways should transect a river mouth or river estuary, there > is nearly universal agreement that marginal seas, including bays, are > mapped with the natural=coastline. > > > > > > Using the rendering at https://www.openstreetmap.de/karte.html - > which differentiates the marine water polygons outside of the coastline > from lakes and rivers, by using slightly different colors, we can see how > bays are mapped in other parts of North America and the world. > > > > > > For example, check out Delaware Bay, just up the coast from your area: > https://www.openstreetmap.de/karte.html?zoom=10&lat=39.14649&lon=-75.07302&layers=B000 > - it is mapped as a natural=bay with natural=coastline around it, not > natural=water > > > > > > Upper and Lower New York Bay are mapped as bays outside of the > natural=coastline - you can see the line where the waterway=riverbank area > starts just at the north end of Manhattan island (though this placement is > somewhat controversial) - > https://www.openstreetmap.de/karte.html?zoom=10&lat=40.63628&lon=-73.93525&layers=B000 > > > > > > Tampa Bay: > https://www.openstreetmap.de/karte.html?zoom=10&lat=27.80801&lon=-82.63368&layers=B000 > - outside of the natural=coastline > > > > > > Galveston Bay: > https://www.openstreetmap.de/karte.html?zoom=10&lat=29.49869&lon=-94.94249&layers=B000TT > - outside of the natural=coastline > > > > > > San Francisco Bay and connected bays: > https://www.openstreetmap.de/karte.html?zoom=10&lat=37.79939&lon=-122.06911&layers=B000TT > - outside of the coastline > > > > > > Puget Sound - while Lake Washington on the east side of Seattle is > natural=water, also most of the ship canal connecting them: > https://www.op
Re: [Tagging] coastline v. water
Hi, On 23.11.20 15:10, David Groom wrote: > Using this logic the Mediterranean Sea, the Red Sea, and the Persian > Gulf should all have the coastline tags removed from their defining ways > and converted to water areas! Italy, Greece, Libya, Egypt and a large > group of other counties would find they had no coastline, which might > come as a surprise to anyone lining there. I'll probably have to inform the tourism guys in Annapolis too and tell them to stop calling themselves a "coastal place" https://patch.com/maryland/annapolis/annapolis-among-20-best-coastal-places-live-magazine ;) sorry folks, you're on an inland waterway. Bit like Richmond really! Bye Frederik -- Frederik Ramm ## eMail frede...@remote.org ## N49°00'09" E008°23'33" ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
See comments below: David -- Original Message -- From: "Eric H. Christensen via Tagging" To: "tagging@openstreetmap.org" Cc: "Eric H. Christensen" Sent: 18/11/2020 20:19:51 Subject: [Tagging] coastline v. water After a few days of much work, a recent collaborative project to turn the Chesapeake Bay from a nothing space outlined by natural=coastline to what we considered to be a more accurate relation of natural=water, we've received some negative feedback. The difference of opinion seems to lie in the definition of what we're mapping. The use of coastline is for "seas"[0] while the use of water is for "inland areas of water"[1]. Even though the Chesapeake Bay is tidal, there is no question that it is an inland waterway (it is completely surrounded by land except for the mouth at its southeast side). Using this logic the Mediterranean Sea, the Red Sea, and the Persian Gulf should all have the coastline tags removed from their defining ways and converted to water areas! Italy, Greece, Libya, Egypt and a large group of other counties would find they had no coastline, which might come as a surprise to anyone lining there. The idea of using coastlines for basically creating an edge between the land and the nothingness of the ocean makes sense when, as far as the eye can see it's only water. Now, some of the feedback that has been presented[2] is that because it is tidal it is part of the sea. I have pointed out that many rivers and streams (and ditches!) are tidal; does that make them part of the sea? I would not think so. In fact, there are named seas on this planet that are not even connected to other water formations (the tiniest, according to the National Geographic, is the Sea of Marmara which has an area just less than 12,950 sq km, larger than the Chesapeake Bay). But, tagging the Chesapeake Bay, and its tributaries, as "water" brings several benefits to the map and the users. First, it helps identify the sections of water that exist in these areas (this can't really be done with node points as there is no way to define start and end points of an area). There are many defined bays, rivers, and streams that make up the greater Chesapeake Bay area. What one may see as one large mass of water is actually many smaller defined segments each with their own history. This is irrelevant to the question of whether the ways should be tagged as natural = coastline. You have had to create a multipolygon containing the ways which form the "sections of water", its perfectly possible to add the "name" tag to this multipolygon without removing the coastline tag from the ways Second, we can speed up any updates (fixes) to outlines of the polygons that happen in these water areas without having to wait for the entire Earth's coastlines to be re-rendered. Changes to tagging should not be done to facilitate easier rendering on one particular map. I suspect having less coastline to render would also speed up the rendering of coastlines as well? Very unlikely. I would like for the tagging community to clarify the different between "water" and "coastline" and when to use each. The definition on water seems to say to use it on inland water but there seems to be, at least, and open interpretation of the word "sea" for coastline that is dragging many inland waters into that category. Thanks, Eric "Sparks" Christensen [0] https://wiki.openstreetmap.org/wiki/Tag:natural%3Dcoastline [1] https://wiki.openstreetmap.org/wiki/Tag:natural%3Dwater [2] https://www.openstreetmap.org/changeset/94093155#map=10/37.1620/-76.1581 ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
Hi, On Sat, Nov 21, 2020 at 07:09:45PM +, Eric H. Christensen via Tagging wrote: > You cannot point to other area that may, in fact, be improperly mapped as an > example when they are like that because locals have been shouted down for > doing it correctly. The fact that this keeps coming back up literally means > that there is not universal agreement that "marginal seas", whatever that > means, are to be mapped with natural=coastline. > > The Chesapeake Bay is an estuary that, by definition, opens to the sea. It > can't be a sea and open to a sea at the same time. In this environment, it is > different from the ocean in which it opens into and is also different from > the tributaries that feed it. These are protected waters for ships. You won't > find any high seas forecasts for the Bay unlike the ocean. The Bay is also > brackish and not defined as salt water, unlike the ocean. There is a very fundamental misunderstanding on how OpenStreetMap works in here. The definition of a tag comes from the agreed-on understanding of the OpenStreetMap community as a whole of what that tag should be. This may or may not agree with defintion of the same word in other contexts. That's just the way it is with defintions. They may differ. You cannot just uniterally apply a definition of coastline that you think is more appropriate, or scientifically correct or whatever and change the map. It is OSM's definition that counts, and OSM's defintion only. That doesn't mean that definitions can't evolve over time but that needs to be discussed when it has a larger impact. natural=coastline is a particular touchy tag here because it is one of the few tags where we rely on a agreed-on definition that works on a planet-scale. Even if you change something relatively locally, it has an effect on how the planet map as a whole is rendered. You can't just apply a new definition to one bay. We must agree on a new definition globally here and apply it globally or the tagging becomes a worthless mess. So please, by all means, start a discussion about a new definition of coastline, make a wiki page, put it up for voting. But all this should be done **before** making any larger changes. For now, please, put the Chesapeake Bay back into its original state. Kind regards Sarah > ‐‐‐ Original Message ‐‐‐ > On Saturday, November 21, 2020 1:14 PM, Joseph Eisenberg > wrote: > > > Eric, > > I don't think the previous discussion is quite as inconclusive as your > > evaluation. > > > > While it is true that there is not widespread agreement on where the > > natural=coatline ways should transect a river mouth or river estuary, there > > is nearly universal agreement that marginal seas, including bays, are > > mapped with the natural=coastline. > > > > Using the rendering at https://www.openstreetmap.de/karte.html - which > > differentiates the marine water polygons outside of the coastline from > > lakes and rivers, by using slightly different colors, we can see how bays > > are mapped in other parts of North America and the world. > > > > For example, check out Delaware Bay, just up the coast from your area: > > https://www.openstreetmap.de/karte.html?zoom=10&lat=39.14649&lon=-75.07302&layers=B000 > > - it is mapped as a natural=bay with natural=coastline around it, not > > natural=water > > > > Upper and Lower New York Bay are mapped as bays outside of the > > natural=coastline - you can see the line where the waterway=riverbank area > > starts just at the north end of Manhattan island (though this placement is > > somewhat controversial) - > > https://www.openstreetmap.de/karte.html?zoom=10&lat=40.63628&lon=-73.93525&layers=B000 > > > > Tampa Bay: > > https://www.openstreetmap.de/karte.html?zoom=10&lat=27.80801&lon=-82.63368&layers=B000 > > - outside of the natural=coastline > > > > Galveston Bay: > > https://www.openstreetmap.de/karte.html?zoom=10&lat=29.49869&lon=-94.94249&layers=B000TT > > - outside of the natural=coastline > > > > San Francisco Bay and connected bays: > > https://www.openstreetmap.de/karte.html?zoom=10&lat=37.79939&lon=-122.06911&layers=B000TT > > - outside of the coastline > > > > Puget Sound - while Lake Washington on the east side of Seattle is > > natural=water, also most of the ship canal connecting them: > > https://www.openstreetmap.de/karte.html?zoom=11&lat=47.59544&lon=-122.39252&layers=B000 > > > > I would like to request that the tidal channels and estuaries around > > Chesapeake Bay be re-mapped with natural=coastline. If you wish to keep the > > natural-water polygons for the estuaries that is not a problem. > > > > But it would be contrary to normal practice to map the main body of > > Chesapeake Bay as natural=water because it is clearly part of the sea - > > there is no barrier between it and the open ocean, since there is an open > > channel through US 13 where the tunnel is. While it is an estuary by > > hydrological definitions, so are the Baltic Sea
Re: [Tagging] coastline v. water
You cannot point to other area that may, in fact, be improperly mapped as an example when they are like that because locals have been shouted down for doing it correctly. The fact that this keeps coming back up literally means that there is not universal agreement that "marginal seas", whatever that means, are to be mapped with natural=coastline. The Chesapeake Bay is an estuary that, by definition, opens to the sea. It can't be a sea and open to a sea at the same time. In this environment, it is different from the ocean in which it opens into and is also different from the tributaries that feed it. These are protected waters for ships. You won't find any high seas forecasts for the Bay unlike the ocean. The Bay is also brackish and not defined as salt water, unlike the ocean. If the rendering engine isn't showing it correctly, fix that; *that's* what's broken. Eric ‐‐‐ Original Message ‐‐‐ On Saturday, November 21, 2020 1:14 PM, Joseph Eisenberg wrote: > Eric, > I don't think the previous discussion is quite as inconclusive as your > evaluation. > > While it is true that there is not widespread agreement on where the > natural=coatline ways should transect a river mouth or river estuary, there > is nearly universal agreement that marginal seas, including bays, are mapped > with the natural=coastline. > > Using the rendering at https://www.openstreetmap.de/karte.html - which > differentiates the marine water polygons outside of the coastline from lakes > and rivers, by using slightly different colors, we can see how bays are > mapped in other parts of North America and the world. > > For example, check out Delaware Bay, just up the coast from your area: > https://www.openstreetmap.de/karte.html?zoom=10&lat=39.14649&lon=-75.07302&layers=B000 > - it is mapped as a natural=bay with natural=coastline around it, not > natural=water > > Upper and Lower New York Bay are mapped as bays outside of the > natural=coastline - you can see the line where the waterway=riverbank area > starts just at the north end of Manhattan island (though this placement is > somewhat controversial) - > https://www.openstreetmap.de/karte.html?zoom=10&lat=40.63628&lon=-73.93525&layers=B000 > > Tampa Bay: > https://www.openstreetmap.de/karte.html?zoom=10&lat=27.80801&lon=-82.63368&layers=B000 > - outside of the natural=coastline > > Galveston Bay: > https://www.openstreetmap.de/karte.html?zoom=10&lat=29.49869&lon=-94.94249&layers=B000TT > - outside of the natural=coastline > > San Francisco Bay and connected bays: > https://www.openstreetmap.de/karte.html?zoom=10&lat=37.79939&lon=-122.06911&layers=B000TT > - outside of the coastline > > Puget Sound - while Lake Washington on the east side of Seattle is > natural=water, also most of the ship canal connecting them: > https://www.openstreetmap.de/karte.html?zoom=11&lat=47.59544&lon=-122.39252&layers=B000 > > I would like to request that the tidal channels and estuaries around > Chesapeake Bay be re-mapped with natural=coastline. If you wish to keep the > natural-water polygons for the estuaries that is not a problem. > > But it would be contrary to normal practice to map the main body of > Chesapeake Bay as natural=water because it is clearly part of the sea - there > is no barrier between it and the open ocean, since there is an open channel > through US 13 where the tunnel is. While it is an estuary by hydrological > definitions, so are the Baltic Sea and all fjords and Puget Sound and San > Francisco Bay - all of which are mapped as outside of the natural=coastline. > > Also please consider that the community here approved the proposal for > waterway=tidal_channel which said that the area of tidal channels (aka tidal > creeks) should be mapped with natural=coastline at their edges - see > https://wiki.openstreetmap.org/wiki/Tag:waterway%3Dtidal_channel#How_to_Map > and > https://wiki.openstreetmap.org/wiki/Proposed_features/Tag:waterway%3Dtidal_channel > - most of the "creek" features along the Bay are tidal channels. > > -- Joseph Eisenberg > > On Thu, Nov 19, 2020 at 6:46 AM Eric H. Christensen via Tagging > wrote: > >> ‐‐‐ Original Message ‐‐‐ >> >> On Wednesday, November 18th, 2020 at 11:34 PM, Brian M. Sperlongano >> wrote: >> >>> This was fascinating reading. I do agree that we ought to have a definition >>> for what gets tagged natural=coastline, and I think it's fine if that >>> definition has some subjectivity. >>> >>> I would offer something as simple as: >>> >>> "The coastline should follow the mean high tide line. In some cases this >>> rule would result in the coastline extending an unreasonable distance along >>> the banks of tidal rivers. In those cases, mappers should identify a >>> reasonable choke point at which to terminate the inland extent of coastline >>> tagging." >> >> I would just classify it as "where the ocean meets the land". Any other >> water that isn't ocean should be mapped as wa
Re: [Tagging] coastline v. water
Eric, I don't think the previous discussion is quite as inconclusive as your evaluation. While it is true that there is not widespread agreement on where the natural=coatline ways should transect a river mouth or river estuary, there is nearly universal agreement that marginal seas, including bays, are mapped with the natural=coastline. Using the rendering at https://www.openstreetmap.de/karte.html - which differentiates the marine water polygons outside of the coastline from lakes and rivers, by using slightly different colors, we can see how bays are mapped in other parts of North America and the world. For example, check out Delaware Bay, just up the coast from your area: https://www.openstreetmap.de/karte.html?zoom=10&lat=39.14649&lon=-75.07302&layers=B000 - it is mapped as a natural=bay with natural=coastline around it, not natural=water Upper and Lower New York Bay are mapped as bays outside of the natural=coastline - you can see the line where the waterway=riverbank area starts just at the north end of Manhattan island (though this placement is somewhat controversial) - https://www.openstreetmap.de/karte.html?zoom=10&lat=40.63628&lon=-73.93525&layers=B000 Tampa Bay: https://www.openstreetmap.de/karte.html?zoom=10&lat=27.80801&lon=-82.63368&layers=B000 - outside of the natural=coastline Galveston Bay: https://www.openstreetmap.de/karte.html?zoom=10&lat=29.49869&lon=-94.94249&layers=B000TT - outside of the natural=coastline San Francisco Bay and connected bays: https://www.openstreetmap.de/karte.html?zoom=10&lat=37.79939&lon=-122.06911&layers=B000TT - outside of the coastline Puget Sound - while Lake Washington on the east side of Seattle is natural=water, also most of the ship canal connecting them: https://www.openstreetmap.de/karte.html?zoom=11&lat=47.59544&lon=-122.39252&layers=B000 I would like to request that the tidal channels and estuaries around Chesapeake Bay be re-mapped with natural=coastline. If you wish to keep the natural-water polygons for the estuaries that is not a problem. But it would be contrary to normal practice to map the main body of Chesapeake Bay as natural=water because it is clearly part of the sea - there is no barrier between it and the open ocean, since there is an open channel through US 13 where the tunnel is. While it is an estuary by hydrological definitions, so are the Baltic Sea and all fjords and Puget Sound and San Francisco Bay - all of which are mapped as outside of the natural=coastline. Also please consider that the community here approved the proposal for waterway=tidal_channel which said that the area of tidal channels (aka tidal creeks) should be mapped with natural=coastline at their edges - see https://wiki.openstreetmap.org/wiki/Tag:waterway%3Dtidal_channel#How_to_Map and https://wiki.openstreetmap.org/wiki/Proposed_features/Tag:waterway%3Dtidal_channel - most of the "creek" features along the Bay are tidal channels. -- Joseph Eisenberg On Thu, Nov 19, 2020 at 6:46 AM Eric H. Christensen via Tagging < tagging@openstreetmap.org> wrote: > ‐‐‐ Original Message ‐‐‐ > > On Wednesday, November 18th, 2020 at 11:34 PM, Brian M. Sperlongano < > zelonew...@gmail.com> wrote: > > > This was fascinating reading. I do agree that we ought to have a > definition for what gets tagged natural=coastline, and I think it's fine if > that definition has some subjectivity. > > > > I would offer something as simple as: > > > > "The coastline should follow the mean high tide line. In some cases > this rule would result in the coastline extending an unreasonable distance > along the banks of tidal rivers. In those cases, mappers should identify a > reasonable choke point at which to terminate the inland extent of coastline > tagging." > > I would just classify it as "where the ocean meets the land". Any other > water that isn't ocean should be mapped as water and tagged appropriately. > That makes the map more accurate and detailed. > > R, > Eric > > ___ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
‐‐‐ Original Message ‐‐‐ On Wednesday, November 18th, 2020 at 11:34 PM, Brian M. Sperlongano wrote: > This was fascinating reading. I do agree that we ought to have a definition > for what gets tagged natural=coastline, and I think it's fine if that > definition has some subjectivity. > > I would offer something as simple as: > > "The coastline should follow the mean high tide line. In some cases this > rule would result in the coastline extending an unreasonable distance along > the banks of tidal rivers. In those cases, mappers should identify a > reasonable choke point at which to terminate the inland extent of coastline > tagging." I would just classify it as "where the ocean meets the land". Any other water that isn't ocean should be mapped as water and tagged appropriately. That makes the map more accurate and detailed. R, Eric ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
‐‐‐ Original Message ‐‐‐ On Wednesday, November 18th, 2020 at 5:04 PM, Christoph Hormann wrote: > > Eric H. Christensen via Tagging tagging@openstreetmap.org hat am 18.11.2020 > > 21:19 geschrieben: > > > [...] > > First: the matter has been discussed at length previously so i would advise > anyone who wants to form an opinion on the matter to read up on past > discussion where essentially everything relevant has been said already. Most > relevant links: > > https://lists.openstreetmap.org/pipermail/tagging/2020-July/054405.html > > and resulting discussion: > > https://lists.openstreetmap.org/pipermail/tagging/2020-August/thread.html#54434 > > https://wiki.openstreetmap.org/wiki/Proposed_Features/Coastline-River_transit_placement Whew, after reading all of those messages, my take-away is that it's mostly what the locals see the water as. > Third: > > While this is ultimately not relevant because the delineation of tags in OSM > should be based on verifiable criteria obviously i have never seen any map > that displays ocean water and inland waterbodies in differentiated form that > shows the Chesapeake Bay as inland water. > > Classical examples with differentiated rendering are TPC/ONC (caution: links > go to large images): Pilot maps don't usually have lines deliniating sections of water. Marine charts do, however. R, Eric ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
This was fascinating reading. I do agree that we ought to have a definition for what gets tagged natural=coastline, and I think it's fine if that definition has some subjectivity. I would offer something as simple as: "The coastline should follow the mean high tide line. In some cases this rule would result in the coastline extending an unreasonable distance along the banks of tidal rivers. In those cases, mappers should identify a reasonable choke point at which to terminate the inland extent of coastline tagging." This would clearly include bays and coves on the marine side of the coast. For rivers, local mappers could decide on where the coastline stops by consensus, and the decision space is limited to a discrete set of chokepoints in the river geography (or when the river stops being tidal if the tidal portion is reasonably short). An objective definition that we can all live with is probably not achievable, but a partially-subjective one would at least minimize the arbitrary decision-making while still allowing flexibility for edge cases. On Wed, Nov 18, 2020 at 5:07 PM Christoph Hormann wrote: > > Eric H. Christensen via Tagging hat am > 18.11.2020 21:19 geschrieben: > > > > [...] > > First: the matter has been discussed at length previously so i would > advise anyone who wants to form an opinion on the matter to read up on past > discussion where essentially everything relevant has been said already. > Most relevant links: > > https://lists.openstreetmap.org/pipermail/tagging/2020-July/054405.html > and resulting discussion: > > https://lists.openstreetmap.org/pipermail/tagging/2020-August/thread.html#54434 > > > https://wiki.openstreetmap.org/wiki/Proposed_Features/Coastline-River_transit_placement > > Second: > > > > > Now, some of the feedback that has been presented[2] is that because it > is tidal it is part of the sea. [...] > > As you can read in the proposal linked above the range of tidal influence > forms the upper limit of the range practical coastline mapping in areas > with significant tidal range but as it is in practical mapping not the > universally used limit. > > Third: > > While this is ultimately not relevant because the delineation of tags in > OSM should be based on verifiable criteria obviously i have never seen any > map that displays ocean water and inland waterbodies in differentiated form > that shows the Chesapeake Bay as inland water. > > Classical examples with differentiated rendering are TPC/ONC (caution: > links go to large images): > > http://legacy.lib.utexas.edu/maps/tpc/americas-pacific-index.html > http://legacy.lib.utexas.edu/maps/onc/txu-pclmaps-oclc-8322829_g_21.jpg > > -- > Christoph Hormann > http://www.imagico.de/ > > ___ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
> Eric H. Christensen via Tagging hat am 18.11.2020 > 21:19 geschrieben: > > [...] First: the matter has been discussed at length previously so i would advise anyone who wants to form an opinion on the matter to read up on past discussion where essentially everything relevant has been said already. Most relevant links: https://lists.openstreetmap.org/pipermail/tagging/2020-July/054405.html and resulting discussion: https://lists.openstreetmap.org/pipermail/tagging/2020-August/thread.html#54434 https://wiki.openstreetmap.org/wiki/Proposed_Features/Coastline-River_transit_placement Second: > > Now, some of the feedback that has been presented[2] is that because it is > tidal it is part of the sea. [...] As you can read in the proposal linked above the range of tidal influence forms the upper limit of the range practical coastline mapping in areas with significant tidal range but as it is in practical mapping not the universally used limit. Third: While this is ultimately not relevant because the delineation of tags in OSM should be based on verifiable criteria obviously i have never seen any map that displays ocean water and inland waterbodies in differentiated form that shows the Chesapeake Bay as inland water. Classical examples with differentiated rendering are TPC/ONC (caution: links go to large images): http://legacy.lib.utexas.edu/maps/tpc/americas-pacific-index.html http://legacy.lib.utexas.edu/maps/onc/txu-pclmaps-oclc-8322829_g_21.jpg -- Christoph Hormann http://www.imagico.de/ ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
On 2020-11-18 21:31, Joseph Eisenberg wrote: > Consider that the natural=coastline is defined as representing the mean high > water springs line, that is, the line of the highest tides. Sorry to pick nits, but tides can be higher than MHWS; the "mean" implies a long-term average, which will often be exceeded.___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
‐‐‐ Original Message ‐‐‐ On Wednesday, November 18th, 2020 at 3:31 PM, Joseph Eisenberg wrote: > Consider that the natural=coastline is defined as representing the mean high > water springs line, that is, the line of the highest tides. If the line on an > open ocean beach is at the high tide line, it makes sense that all tidal bays > and estuaries should also be included in the area outside of the coastline. Then why the ability to mark natural=water as tidal and as salt? Clearly the ability to use those attributes leads me to believe that just being tidal does not make it be coastline. --Eric ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
Re: [Tagging] coastline v. water
Chesapeake Bay, as the name “Bay” suggests, is a bay at the edge of the Atlantic Ocean. It is a shallow estuary, similar to many othe partially enclosed margins seas, e.g. the Salish Sea (including Puget Sound) in Washington/British Columbia, San Francisco Bay in California, the Tampa Bay in Florida, etc. It has always been the standard to map these bays as part of the marine environment by using the natural=coastline to include them as part of the marginal sea. Consider that the natural=coastline is defined as representing the mean high water springs line, that is, the line of the highest tides. If the line on an open ocean beach is at the high tide line, it makes sense that all tidal bays and estuaries should also be included in the area outside of the coastline. While there is some debate about where on the Potomac River we should put the line (I would suggest around DC, where the river widens out), there is no doubt that Chesapeake Bay is part of the marine environment. — Joseph Eisenberg On Wed, Nov 18, 2020 at 12:24 PM Eric H. Christensen via Tagging < tagging@openstreetmap.org> wrote: > After a few days of much work, a recent collaborative project to turn the > Chesapeake Bay from a nothing space outlined by natural=coastline to what > we considered to be a more accurate relation of natural=water, we've > received some negative feedback. > > The difference of opinion seems to lie in the definition of what we're > mapping. The use of coastline is for "seas"[0] while the use of water is > for "inland areas of water"[1]. Even though the Chesapeake Bay is tidal, > there is no question that it is an inland waterway (it is completely > surrounded by land except for the mouth at its southeast side). The idea > of using coastlines for basically creating an edge between the land and the > nothingness of the ocean makes sense when, as far as the eye can see it's > only water. > > Now, some of the feedback that has been presented[2] is that because it is > tidal it is part of the sea. I have pointed out that many rivers and > streams (and ditches!) are tidal; does that make them part of the sea? I > would not think so. In fact, there are named seas on this planet that are > not even connected to other water formations (the tiniest, according to the > National Geographic, is the Sea of Marmara which has an area just less than > 12,950 sq km, larger than the Chesapeake Bay). > > But, tagging the Chesapeake Bay, and its tributaries, as "water" brings > several benefits to the map and the users. First, it helps identify the > sections of water that exist in these areas (this can't really be done with > node points as there is no way to define start and end points of an area). > There are many defined bays, rivers, and streams that make up the greater > Chesapeake Bay area. What one may see as one large mass of water is > actually many smaller defined segments each with their own history. > Second, we can speed up any updates (fixes) to outlines of the polygons > that happen in these water areas without having to wait for the entire > Earth's coastlines to be re-rendered. I suspect having less coastline to > render would also speed up the rendering of coastlines as well? > > I would like for the tagging community to clarify the different between > "water" and "coastline" and when to use each. The definition on water > seems to say to use it on inland water but there seems to be, at least, and > open interpretation of the word "sea" for coastline that is dragging many > inland waters into that category. > > Thanks, > Eric "Sparks" Christensen > > [0] https://wiki.openstreetmap.org/wiki/Tag:natural%3Dcoastline > [1] https://wiki.openstreetmap.org/wiki/Tag:natural%3Dwater > [2] > https://www.openstreetmap.org/changeset/94093155#map=10/37.1620/-76.1581 > > ___ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > ___ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
