Viewing 15 posts - 1 through 15 (of 16 total)
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  • #47226
    karlchick
    Participant

    1. Marshes
    It seems that (at least in the UK) that marshes are usually tagged as:
    natural = “wetland” & wetland = “marsh”
    would it be possible to get these items grouped with natural=”marsh”?
    Note: I am not seeing anything (so far) in the uk tagged with natural=”marsh” that is in fact a marsh…

    2. Tidalflats
    it seems that OAM groups everything marked as natural=”wetland” together regardless of the sub-tag wetland:

    wetland key is not used and all different types of wetlands are grouped together in OAM.
    – bog (has vegetation)
    – swamp (has vegetation)
    – marsh (has vegetation)
    – reedbed (has vegetation)
    – wet_meadow (has vegetation)
    – mangrove (has vegetation)
    – tidalflat (tidal mud/sand no vegetation)
    – saltmarsh (has vegetation)

    The issue I have is that tidal flats occurs in estuaries and wide rivers and are more akin to sand than wetland.
    All the other types of wetland have vegetation. I really think they should be separated…

    In my OS theme I want to show tidal flats (as Ordnance Survey maps do) as coloured sand like areas. However, for all the other types of wetland I do not want to use a coloured in area, just filled with blue scrub/vegetation symbol.

    Would it be possible to somehow indicate that wetland with wetland=”tidalflat” are different?
    I noticed that sometimes some wetlands that correspond to tidalflats have surface=”raw” set, but this is not consistent, so presume is down to specific taggers. Perhaps the OAM map scripts could set surface=”raw” for all wetland=”tidalflat”?
    The issue I have is that wetland is also used for tidalflat.

    I partially solve this by drawing the wetland with symbols first, then water (erases the symbols) and then tint the wetland with transparent mud colour – to avoid deleting the blue marsh symbols… but this results in all wetlands being tinted rather than white.

    Attached are image showing the issue I currently have. All show “OS map | OAM map | OSM data”:
    – tidalflat.jpg shows how the river mid is faintly down (I want these to be solid sand coloured)
    – marsh.jpg shows how a marsh and the water areas are tinted by the colour tinting (I don’t want these coloured)

    #47233
    Tobias
    Keymaster

    1. Marshes
    It seems that (at least in the UK) that marshes are usually tagged as:
    natural = “wetland” & wetland = “marsh”
    would it be possible to get these items grouped with natural=”marsh”?
    Note: I am not seeing anything (so far) in the uk tagged with natural=”marsh” that is in fact a marsh…

    I think that’s not necessary, natural=marsh isn’t used anymore. It was before, and it’s best to use as equivalent to natural=wetland, if at all.

    it seems that OAM groups everything marked as natural=”wetland” together regardless of the sub-tag wetland:

    No, sub-tag wetland isn’t contained in the maps, only natural=wetland, which by itself groups everything together :-), not OAM. With mapsforge every tag that should be in the maps has to be in the tag-mapping file, up til now wetland=* wasn’t requested.

    Many other themes/maps based on OSM use something like Carto in the bottom right of your screenshot – transparent pattern without plant symbols but with “water stripes” – this works for all kind of wetlands in my opinion. Sowing tidal flats like sand would leave the impression that’s you can pass it anytime – I don’t know if that’s a good idea?

    Setting surface=raw (which is a OAM-specific tag group for certain highway surfaces) for other tags which don’t originally have a surface=* would be mixing up things which don’t belong together. Better adding just wetland=tidalflat, but I’m not sure if this really necessary – especially if there are so many other wetland=* and it’s mostly just means off limits for hikers and cyclists :-)

    Developer of Elevate mapstyle

    1 user thanked author for this post.
    #47236
    karlchick
    Participant

    Well… my quest is to emulate the OS maps…

    These tidalflats are substantial structures, usually mud/sediment banks that may or may not be submerged at high tide, but are very prominent at most of the time.

    Attached is a satelite view of the example from Longney above.

    Hence i want to emulate the OS maps and make these more solid in appearance, but not the inland wetlands.

    I suspect the UK being an island nation has a lot more of these type of land features than land locked countries.

    #47239
    karlchick
    Participant

    Could we have the tag wetlands=* added to OAM?
    – Living in a country that has so many different wetlands it would help improve the map rendering considerably.
    – This would have no negative impact on existing themes, since it is a sub-tag of natural=wetland.

    I’m sure there are many other types of activities other than hiking and cycling that use OAM maps and would appreciate this, e.g. canoeing, coast steering, bird watchers etc.

    #47245
    Tobias
    Keymaster

    As written above, wetland=* doesn’t do much to improve the main usage of the maps, which is hiking and cycling. Of course we have tidal flats in Germany, too. The main improvement would be that it’s an area where you’re able to walk in low tide in contrast to most other permanent wetlands, which are wet all the time.

    We concentrate on hiking and cycling as it’s not possible to analyze, add and preprocess all tags that are needed for other special uses. We already had users who would have liked watersports, horse riding or public transport tags in OAM. This would just eat human and technical ressources, make the maps even larger and with the tag limit of 15 per way it would also result in white tiles without any map data.

    But in this case, I think as the main tag (natural=wetland) is already in the map, it would probably mean not much additional ressources, especially as the ways are already there. What do you think, Christian?

    Those wetland tags are probably the ones to add, all more than 2000 times in OSM:
    bog
    marsh
    swamp
    reedbed
    wet_meadow
    mangrove
    tidalflat
    saltmarsh
    fen
    string_bog
    dambo
    mud

    Except of dambo, all are in the Wiki, and dambo is an African speciality. Of the more common tags, wetland=saltern shouldn’t be used, so this shouldn’t be added.

    If we do this, it would make sense to delete natural=marsh from tag-mapping, as it doesn’t occur in OSM anymore, and separate natural=mud.

    Developer of Elevate mapstyle

    2 users thanked author for this post.
    #47263
    ChristianK
    Keymaster

    What do you think, Christian?

    These Tags does#nt add much value to hikes and cyclists.
    Every tag adds size to the maps.
    Every tag have to be prozessed on device against the theme – this adds prozessing overhead.

    Sorry folks, we make Hike/Cycle maps – already with a lot of tags for common/recreational use of the maps.
    If someone wants to add Buildings, Waymarks, windmills, towers – a special kind of shop – OK
    but for sub-tags of wetlands – just to come close to OSM-Mapnik look = no

    1 user thanked author for this post.
    #47362
    karlchick
    Participant

    I have a better suggestion. Having looked at a lot of coastal regions around the UK I noticed that there are many places where landscape areas that are accessible by foot only at low tide. These might include sand, rock, wetlands etc.

    They all seem to use tidal=yes which has 39,995 uses in tag-info.

    There are understandably a lot of footpaths around coastal regions (they offer wonderful views), and most are not affected by the tide; but some are. I would consider it useful and important for walkers to know which footpaths are crossing tidal areas and hence may not be accessible during high tide…

    Could this non-drawable tag be included?

    • This reply was modified 4 months ago by karlchick.
    #47373
    ChristianK
    Keymaster

    Hi Karl,

    tidal=yes

    Yes thats possible:

    <osm-tag key='tidal' value='td_yes' equivalent-values='yes' renderable='false' />

    “td_yes” cause of the CommonValueBug

    • This reply was modified 4 months ago by ChristianK.
    1 user thanked author for this post.
    #47377
    JohnPercy
    Participant

    Yes, but…
    The key/value combination tidal=yes applies up the the “coastline” line, which is the spring tide high water mark – the highest normal high water level.
    If “mud, sand, rock etc are drawn semi-transparently and after “sea” then the tidal area is effectively already shown. I think this new tag would add little..
    My phone battery has just died so I can’t attach the screenshots I would like but here is one I did earlier showing sand above and below the high water mark. What is not immediately obvious in this screenshot is that it also shows marsh/wetland above and below the high water mark. (There’s a small margin above HWM represented by portions of the marsh symbols)

    #47381
    JohnPercy
    Participant

    Some more screenshots

    #47386
    JohnPercy
    Participant

    One more, a genuine tidal footpath.

    #47389
    karlchick
    Participant

    I agree that using semi-transparent features can alleviate the problem. I have so started to adapt my theme to use semi-transparent features.

    However, the point of having customisable themes is to support different ways of visualising the map data… having the “tidal=td_yes” opens a whole new set of possibilities in theming.

    E.g. different theme settings for land based wetland (marshes, bogs, etc) from tidal wetland (mud, sand, rock, etc). Option of using solid areas to avoid the tiling artefact issue at low zooms levels. It might so allow tidal areas to be universally tinted, bit like forced roads, hence even roads that are not marked as Ford would also be indicated as affected by tides….

    I would very much appreciate having the “tidal=td_yes” added.

    #47441
    karlchick
    Participant

    Thank you Christian for adding tidal=td_yes. I am playing around with some the possibilities this provides (e.g. Blue dashes for tidal footpaths instead of usual green dashes – something i have noticed OS maps started to use) and most are working great.

    But there is one thing that I am disappointed with, it is more to do with the way tagging in OSM is done…
    Wetland=tidalflat is assumed (it seems) to be tidal and so some taggers do not set tidal=yes, and some do.

    Given that tidalflats are by definition tidal, would be possible to automatically set tidal=td_yes for all wetland=tidalflat in OAM generation?

    #47569
    karlchick
    Participant

    Bumping the request I tagged onto the end of thankyou post (in case it got overlooked)… i.e. a request for auto-setting of tidal=td_yes for tidalflat areas…

    It seems (looking at the a large number of areas in OSM) that areas tagged wetland=tidalflat do not normally get tidal=yes tag set, presumably because by definition a tidalflat is tidal.

    However, given than OAM maps do not include the wetland sub-tags, it is impossible to check if a wetland is tidal or not based on the tidal=td_yes.

    My request/question is: would it be possible to automatically set tidal=td_yes for all wetland=tidalflat at part of the OAM generation?

    #47663
    ChristianK
    Keymaster

    Done for testing.
    If there are any sidefects it will be removed.

    1 user thanked author for this post.
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