[talk-ch] Confine nazionale impreciso sul Monte Generoso / Ungenaue Landesgrenze auf dem Monte Generoso

Raphael dafadllyn at gmail.com
Fri Sep 10 22:13:21 CEST 2021


On Thu, 9 Sept 2021 at 07:20, Sascha Brawer <sascha at brawer.ch> wrote:
>
> It’s complicated. [...]

Thanks, Sascha, for the informative links.

On Thu, 9 Sept 2021 at 17:27, Simon Poole <simon at poole.ch> wrote:
> There are at least some
> indications that it might be partially a projection issue, see
> https://cloud.sosm.ch/index.php/s/oJNE5P4dP3db7YG
>
> But in numerous places it seems to simply be different (clearly the
> already mentioned simplification could be part of that)

Here's the situation on Monte Generoso – the light blue line is the
boundary according to the Regione Lombardia and the red line according
to swissBOUNDARIES3D:

https://drive.google.com/file/d/1BIdJiHYAsnLMSGz6CqevYeiemCGHoqld/view?usp=sharing

I don't know why the boundaries differ so much and so irregulary
(astonishingly the orthophotos from Swisstopo and from the Regione
Lombardia are almost congruent). In any case, the boundary from
swissBOUNDARIES3D runs through the boundary stones (e.g. [1]) while
that from Regione Lombardia doesn't. Therefore i'll not ajust the
boundary to that from the Regione Lombardia. Instead i'm going to move
it to the boundary stones that i mapped or improved. This is likely
not 100 % accurate (as i wrote, there are probably some boundary
markers on the ground, which i haven't noticed), but still better than
the current situation.

[1]: https://commons.wikimedia.org/wiki/File:Cippo_di_confine_Monte_Generoso_n%C2%B0_24.jpg

Best regards and a nice weekend to everyone

Raphael


On Thu, 9 Sept 2021 at 17:27, Simon Poole <simon at poole.ch> wrote:
>
>
> Am 08.09.2021 um 22:05 schrieb Raphael:
> > Hello Simon
> >
> > No problem and thanks for the link!
> >
> > I've found a data record with the administrative boundaries from 2020.
> > [^1] But strangely enough, that boundary [^2] looks totally different
> > from swissBOUNDARIES3D. I've connected the boundary stones, whose
> > position I have improved using Swissimage, with a way [^3], which is
> > pretty congruent with swissBOUNDARIES3D. Do you have an idea why there
> > is such a big difference between the boundary by the Regione Lombardia
> > and swissBOUNDARIES3D? This can't be because of different geodetic
> > systems and i've also never heard that the Swiss-Italian boundary were
> > disputed.
>
> As Sascha has pointed out it isn't so simple with "no disputes" but I
> don't think this is the cause for the mismatch. There are at least some
> indications that it might be partially a projection issue, see
> https://cloud.sosm.ch/index.php/s/oJNE5P4dP3db7YG
>
> But in numerous places it seems to simply be different (clearly the
> already mentioned simplification could be part of that)
>
> Simon
>
> > Best regards
> >
> > Raphael
> >
> > [^1]:https://www.geoportale.regione.lombardia.it/download-pacchetti?p_p_id=dwnpackageportlet_WAR_gptdownloadportlet&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&_dwnpackageportlet_WAR_gptdownloadportlet_metadataid=%7BA1D3FFE5-BA78-43BB-8EE5-D892DC55A29F%7D
> > [^2]:https://www.openstreetmap.org/way/981025241
> > [^3]:https://www.openstreetmap.org/way/981024609
> >
> >
> > On Tue, 7 Sept 2021 at 12:15, Simon Poole<simon at poole.ch>  wrote:
> >> Sorry that this has taken so long, our Italian colleagues have pointed
> >> tohttps://www.geoportale.regione.lombardia.it/  as a potential source of
> >> OGD for the border.
> >>
> >> Simon
> >>
> >>
> >> Am 05.08.2021 um 22:32 schrieb Raphael:
> >>>> There are no boundaries in Lake Constance, there are some ways in OSM to
> >>>> close the polygons from a practical pov, but there are no international
> >>>> boundaries there that they could correspond to
> >>> Thanks for the information. :) (I thought I heard that once, but
> >>> wasn't sure anymore.)
> >>>
> >>>> Politically I don't think it would be a good move to try this again
> >>>> right now.
> >>> Okay.
> >>>
> >>>> I can definitely ask OSM Italia for some help with the
> >>>> specific issue.
> >>> That would be very helpful.
> >>>
> >>> Cheers
> >>>
> >>> Raphael
> >>>
> >>> On Thu, 5 Aug 2021 at 22:09, Simon Poole<simon at poole.ch>  wrote:
> >>>> Am 05.08.2021 um 21:31 schrieb Raphael:
> >>>>> Hi Simon, hi everyone!
> >>>>>
> >>>>> Unfortunately, the link on
> >>>>> https://wiki.openstreetmap.org/wiki/ISTAT_Italian_Borders  doesn't work
> >>>>> anymore. I also can't improve the boundary with the help of the
> >>>>> boundary stones, because some stones are missing in OSM. (I couldn't
> >>>>> access them because they are in a fenced pasture.) Besides, the
> >>>>> boundary from swissBOUNDARIES3D changes its direction more often than
> >>>>> there are boundary stones. (Maybe there are some boundary markers on
> >>>>> ground level which i haven't noticed.)
> >>>>>
> >>>>> I've compared the Swiss border in OSM with swissBOUNDARIES3D: While
> >>>>> there are only minor differences on the northern boundary from Geneva
> >>>>> to the Lower Engadine (except from the Lake Constance, where the
> >>>>> boundaries differ up to 1.3 km),
> >>>> There are no boundaries in Lake Constance, there are some ways in OSM to
> >>>> close the polygons from a practical pov, but there are no international
> >>>> boundaries there that they could correspond to (the swisstopo boundaries
> >>>> are just as make-believe, simply slightly different dreaming).
> >>>>
> >>>>> there are larger differences (as i
> >>>>> have seen up to 70 m) on the southern boundary (e.g. between Pas de
> >>>>> Morgins and Mont Dolent). It doesn't seem that all these differences
> >>>>> would come from simplification.
> >>>>>
> >>>>> It would be very helpful if we could use the new swissBOUNDARIES3D.
> >>>>> Who asked Swisstopo at the time if we could use this data?
> >>>> I did.
> >>>>
> >>>> Politically I don't think it would be a good move to try this again
> >>>> right now. I can definitely ask OSM Italia for some help with the
> >>>> specific issue.
> >>>>
> >>>> Simon
> >>>>
> >>>>
> >>>>> Best regards
> >>>>>
> >>>>> Raphael
> >>>>>
> >>>>> On Tue, 3 Aug 2021 at 12:14, Simon Poole<simon at poole.ch>  wrote:
> >>>>>> Am 01.08.2021 um 22:18 schrieb Raphael:
> >>>>>>> Hi Simon
> >>>>>>>
> >>>>>>> Thank you very much for your reply!
> >>>>>>>
> >>>>>>> The nodes don't seem to have changed since the import (they are all
> >>>>>>> version 1). Where can i get the original source to check whether it
> >>>>>>> was correct or wrong there? If the original source is correct, i could
> >>>>>>> redraw the national border with it.
> >>>>>> The problem could be that at the time we (well not me because I was a
> >>>>>> neophyte at the time :-)) applied some simplification to the data for
> >>>>>> technical reasons, which in general shouldn't cause such problems, but
> >>>>>> maybe it is the reason here. Or something else, but I didn't find
> >>>>>> anything obvious.
> >>>>>>
> >>>>>> But in any casehttps://www.openstreetmap.org/node/1372930109  is in the
> >>>>>> correct place, buthttps://www.openstreetmap.org/node/1372930116  seems
> >>>>>> to be a bit off, it should be further to the east, on the other side.
> >>>>>> The simplest way to fix it is to find an Italian open data source for
> >>>>>> the coordinates
> >>>>>> (https://wiki.openstreetmap.org/wiki/ISTAT_Italian_Borders  maybe), or
> >>>>>> survey the boundary stone if there is one there (or it might actually be
> >>>>>> visible on imagery).
> >>>>>>
> >>>>>> Simon
> >>>>>>
> >>>>>>
> >>>>>>> Best regards
> >>>>>>>
> >>>>>>> Raphael
> >>>>>>>
> >>>>>>> On Sun, 1 Aug 2021 at 21:59, Simon Poole<simon at poole.ch>  wrote:
> >>>>>>>> The thing is that the boundaries were originally imported from
> >>>>>>>> swissBoundaries3D with explicit permission from swisstopo see
> >>>>>>>> https://wiki.openstreetmap.org/wiki/Switzerland/swissBOUNDARIES3D  . In
> >>>>>>>> the mean time the legal situation has changed and have to assume that at
> >>>>>>>> least currently the data is off limits.
> >>>>>>>>
> >>>>>>>> Now naturally the probably more interesting question is why is there
> >>>>>>>> such a big difference? Was this in the original data or is it simply an
> >>>>>>>> editing error (then likely the issue can be undone).
> >>>>>>>>
> >>>>>>>> Simon
> >>>>>>>>
> >>>>>>>> Am 01.08.2021 um 21:22 schrieb Raphael:
> >>>>>>>>> Hi everyone
> >>>>>>>>>
> >>>>>>>>> Can no one tell me if it is still allowed to use swissBOUNDARIES3D?
> >>>>>>>>>
> >>>>>>>>> Best regards
> >>>>>>>>>
> >>>>>>>>> Raphael
> >>>>>>>>>
> >>>>>>>>> On Thu, 22 Jul 2021 at 23:11, Raphael<dafadllyn at gmail.com>  wrote:
> >>>>>>>>>> (Unten auf Deutsch)
> >>>>>>>>>>
> >>>>>>>>>> Ciao a tutti
> >>>>>>>>>>
> >>>>>>>>>> Ho notato che il confine nazionale sul Monte Generoso è impreciso su
> >>>>>>>>>> OSM (errore tra 3 e 10 metri). Per quanto ne so, le cippi di confine
> >>>>>>>>>> degli anni 1900 e 1914 sono ancora valide – ma in OSM il confine corre
> >>>>>>>>>> accanto alle cippi di confine (esempio [1]). Inoltre, la Cappelletta
> >>>>>>>>>> della Madonna della Provvidenza  è in territorio svizzero – ma in OSM
> >>>>>>>>>> è in Italia. [2]
> >>>>>>>>>>
> >>>>>>>>>> Mi è permesso di correggere il confine con l'aiuto di
> >>>>>>>>>> swissBOUNDARIES3D [3]? Posso importare lo shapefile direttamente in
> >>>>>>>>>> JOSM, o devo ancora convertire il sistema di riferimento delle
> >>>>>>>>>> coordinate?
> >>>>>>>>>>
> >>>>>>>>>> Cordiali saluti
> >>>>>>>>>>
> >>>>>>>>>> Raphael
> >>>>>>>>>>
> >>>>>>>>>> [1]:https://www.openstreetmap.org/node/8911035901
> >>>>>>>>>> [2]:https://www.openstreetmap.org/way/416328502
> >>>>>>>>>> [3]:https://www.swisstopo.admin.ch/de/geodata/landscape/boundaries3d.html
> >>>>>>>>>>
> >>>>>>>>>> ----
> >>>>>>>>>>
> >>>>>>>>>> Hallo zusammen
> >>>>>>>>>>
> >>>>>>>>>> Mir ist aufgefallen, dass die Landesgrenze auf dem Monte Generoso bei
> >>>>>>>>>> OSM ungenau verläuft (Fehler zwischen 3 und 10 Meter). Meines Wissens
> >>>>>>>>>> sind die Grenzsteine aus den Jahren 1900 und 1914 nach wie vor gültig
> >>>>>>>>>> – bei OSM verläuft die Grenze jedoch neben den Grenzsteinen (Beispiel
> >>>>>>>>>> [1]). Ausserdem befindet sich die Cappelletta della Madonna della
> >>>>>>>>>> Provvidenza auf Schweizer Boden – in OSM befindet sich sich jedoch in
> >>>>>>>>>> Italien. [2]
> >>>>>>>>>>
> >>>>>>>>>> Darf ich die Grenze mithilfe von swissBOUNDARIES3D [3] korrigieren?
> >>>>>>>>>> Kann ich das Shapefile direkt in JOSM importieren, oder muss ich noch
> >>>>>>>>>> eine Konvertierung des Koordinatenreferenzsystems vornehmen?
> >>>>>>>>>>
> >>>>>>>>>> Beste Grüsse
> >>>>>>>>>>
> >>>>>>>>>> Raphael
> >>>>>>>>>>
> >>>>>>>>>> [1]:https://www.openstreetmap.org/node/8911035901
> >>>>>>>>>> [2]:https://www.openstreetmap.org/way/416328502
> >>>>>>>>>> [3]:https://www.swisstopo.admin.ch/de/geodata/landscape/boundaries3d.html
> >>>>>>>>> _______________________________________________
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