Re: [OSM-talk-ie] Summits imported from mountainviews.ie

[Donal Hunt]

And for those (like me) who are not up to speed on how peaks are measured…


The World Geodetic System (WGS) is a standard for use in cartography
, geodesy
, and satellite navigation
 including GPS
.

WGS84 (elipsoid) and EGM96 (geoid) are two different models, with different
applications.

The latest major revision of WGS 84 is also referred to as "Earth
Gravitational Model 1996" (EGM96), first published in 1996, with revisions
as recent as 2004. This model has the same reference ellipsoid as WGS 84,
but has a higher-fidelity geoid (roughly 100 km resolution versus 200 km
for the original WGS 84).


When you see a height in a map, it is usually a height over the geoid
(orthometric height), but when you get one from a GPS device, it is usually
a height over the elipsoid. There are online tools to transform between
them as needed, using what it is called geoid undulation. E.g.
geoid-height-calculator


The tl;dr is that you need to reference which model your peak height is
measured against. EGM96 is preferred (I'm assuming) because it has higher
definition and more refined model.


Donal

On Fri, 29 Nov 2019, 19:00 moltonel 3x Combo,  wrote:

> Hi,
>
> I've just fixed Lugnaquilla's "ele" tag to use the EGM96 system, as
> opposed to the WGS84 one:
> https://www.openstreetmap.org/changeset/77737107
> https://wiki.openstreetmap.org/wiki/Key:ele?uselang=en
>
> That one was reported by an OSM note, but I wouldn't be surprised if
> most of the natural=peak have the same issue. I think it's possible to
> find those using an overpass query that would return all natural=peak
> where ele == ele::egs84, but I couldn't figure that query out straight
> away and there may be a lot of stuff to carefully fix, so I'm turning
> to the mailing list.
>
> Might get a solution tomorrow during the Kilkenny meetup, but I
> figured I might as well ask here so I don't forget about it.
>
>
> --
> Vincent de Phily
>
> ___
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>
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Re: [OSM-talk-ie] Time-lapse video of map edits

[Dave Corley]

That's a class animation John

On Fri 29 Nov 2019, 17:26 John Kennedy,  wrote:

> Powerful stuff Heikki. Will give it a whirl when I get a chance. Best of
> luck to those in Kilkenny tomorrow
>  - John
>
> On Thu, 28 Nov 2019 at 23:11, Heikki Vesanto 
> wrote:
>
> > Hi John,
> >
> > Looks great! Good work.
> >
> > Using the actual added dates is a bit trickier.
> >
> > You need the full history extracts for that. Then you can loop through
> > it with osmium-tools essentially creating a snapshot. This can be done
> > for example with python.
> >
> > I wrote a guide on it:
> > https://gisforthought.com/creating-openstreetmap-history-visualisations/
> >
> > But the visualization part should work the same as you did here, with
> > QGIS and the time manager plugin.
> >
> > -Heikki
> >
> > On Thu, Nov 28, 2019 at 10:50 PM John Kennedy 
> > wrote:
> > >
> > > Hi. I was able to generate a time-lapse video but it is based on the
> time
> > > data was last edited rather than the time the data was first added.
> > >
> > > Packaged it up and available here in case anyone finds it useful:
> > > https://www.youtube.com/watch?v=w7xTAJ2j8gI
> > >
> > > Has anyone suggestions on how to download data from OSM that includes
> > time
> > > info (for processing in QGIS)?
> > >
> > > Thanks/
> > >  - John.
> > > ___
> > > Talk-ie mailing list
> > > Talk-ie@openstreetmap.org
> > > https://lists.openstreetmap.org/listinfo/talk-ie
> >
> > ___
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> > Talk-ie@openstreetmap.org
> > https://lists.openstreetmap.org/listinfo/talk-ie
> >
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[OSM-talk-ie] Summits imported from mountainviews.ie

[moltonel 3x Combo]

Hi,

I've just fixed Lugnaquilla's "ele" tag to use the EGM96 system, as
opposed to the WGS84 one:
https://www.openstreetmap.org/changeset/77737107
https://wiki.openstreetmap.org/wiki/Key:ele?uselang=en

That one was reported by an OSM note, but I wouldn't be surprised if
most of the natural=peak have the same issue. I think it's possible to
find those using an overpass query that would return all natural=peak
where ele == ele::egs84, but I couldn't figure that query out straight
away and there may be a lot of stuff to carefully fix, so I'm turning
to the mailing list.

Might get a solution tomorrow during the Kilkenny meetup, but I
figured I might as well ask here so I don't forget about it.


-- 
Vincent de Phily

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Re: [OSM-talk-ie] Time-lapse video of map edits

[John Kennedy]

Powerful stuff Heikki. Will give it a whirl when I get a chance. Best of
luck to those in Kilkenny tomorrow
 - John

On Thu, 28 Nov 2019 at 23:11, Heikki Vesanto 
wrote:

> Hi John,
>
> Looks great! Good work.
>
> Using the actual added dates is a bit trickier.
>
> You need the full history extracts for that. Then you can loop through
> it with osmium-tools essentially creating a snapshot. This can be done
> for example with python.
>
> I wrote a guide on it:
> https://gisforthought.com/creating-openstreetmap-history-visualisations/
>
> But the visualization part should work the same as you did here, with
> QGIS and the time manager plugin.
>
> -Heikki
>
> On Thu, Nov 28, 2019 at 10:50 PM John Kennedy 
> wrote:
> >
> > Hi. I was able to generate a time-lapse video but it is based on the time
> > data was last edited rather than the time the data was first added.
> >
> > Packaged it up and available here in case anyone finds it useful:
> > https://www.youtube.com/watch?v=w7xTAJ2j8gI
> >
> > Has anyone suggestions on how to download data from OSM that includes
> time
> > info (for processing in QGIS)?
> >
> > Thanks/
> >  - John.
> > ___
> > Talk-ie mailing list
> > Talk-ie@openstreetmap.org
> > https://lists.openstreetmap.org/listinfo/talk-ie
>
> ___
> Talk-ie mailing list
> Talk-ie@openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-ie
>
___
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