Bugs river/ocean
  • Hi,

    https://www.openstreetmap.org/edit#map=16/47.3991/-0.2966

    on the right, the river view "La Loire" is ok
    on the left the display is not done

    Thx.

    image
  • 15 Comments sorted by
  • Maybe it's an osm bug ?!
    You would have an idea about the problem ?!
  • From time to time there a rendering issues especially for rivers and lakes. If I remember well, mostly resulting from errors from OSM data, but sometimes MF does not fully understand OSM data even if they are correct. No idea, what causes the problem here. Anyway at least for car use it seems to be rather evident, that there is a river. If you are traveling on a boat, that might be different. But I would not use MF for "navigating" on water.
  • I do not know what the reason is in this case, but often it is due to duplication of the same feature due to being in two administrative areas
  • Anyway rendering is as exspected, when I use Openandromaps with Oruxmaps. They do it better than MF ;)
  • Hello,
    The bug is not only for rivers, ...
    I was told there is no water in Venice!
    :))

    image
  • But there are no streets as well. So don't worry, you will not be navigated into water. It is just a question, how it looks like.

    Just a couple of days I had an e-mail conversation with the creator of Openandromaps about the river Mosel, having no water also at some parts between Luxemburg and Germany. Since there is water in Mapnik online-maps he argued, that the online map format is more tolerant to faulty data in relations than his maps, which are created following the Mapsforge format. I have no clue about these technical things, I can just report, what he wrote to me.
  • I agree with you Oldie, but the appearance is important for the seriousness of the application.

    Another Gps application that also uses OSM does not have this display problem.

    Image below:

    image
  • The image of the beginning of this topic in comparison:

    image
  • Your other GPS app. What is it? And how old are the maps?
    Is it NavFree or Navmii? If so: check the date of the maps, probably 2016. They can be more than a year old. If a new OSM bug arises MNF will "detect" :) it quite soon because the maps are often updated.
    Do not simply compare maps from nav apps with each other without compairing map dates.
  • "check the date of the maps"

    That is, why in the case of the river Mosel (see above) I downloaded the latest Openandromaps before "complaing".

    I have checked now the Mapfactor map Germany as well and there the river Mosel does also have no water in it (near the city of Apach). It seems, that it is the same fault as with Openandromaps. That is an indication for me, that OSM data is not correct there.
  • Ok, I agree with you, but what is the real problem so that we can fix it and have a map with water where there should be water, that would be more serious, right? !
  • All these rivers and big lakes (Lac Neufchatel/lac de Geneva, Bodensee, etc) and rivers Loire, Rhine, Mosel, etc. are all built up of "(multi)polygons". These get easily "broken". 
    A second error is if the multipolygon is split over two (or more) "administrative boundaries".
    Multiple map programs go wrong here. Openstreetmap is just one big database and you can just pan and zoom from Northern to Southern Germany or France.
    Nav apps often have to split up maps due to the 2GB limit on sdcards. If the map making software is "breaking" a multipolygon, you see nothing or just a single line (in case of a river).
  • " If the map making software is "breaking" a multipolygon, you see nothing or just a single line (in case of a river)" (By the way, I miss a quote function in this forum)

    Exactly such a single line you find in the Germany map of Openandromaps just a few km up the river Mosel from Apach, where the river "leaves" the map.

    But near Apach this must be such a split polygon. I tried to fix this with the Vespucci Android app. But since I am not very familiar with this app, I did not find, how to do it.

    Now I do not find any errors here. https://www.openstreetmap.org/way/368502304 The last edit was one month ago. Maybe the coming Mapfactor map will be ok already.

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