Thanks Mark, not only for the solutions but also the explanations. Very
helpful.
On Wed, 6 Nov 2019 at 23:16, Mark Tully wrote:
> Hi Brian,
>
> Regarding your overpass issue, there's some optimizing of the query that
> could help you if all you need is to count the number of relations. The
> overpass wizard, by default, requests the tags, ids and geometry of the
> objects which match the query. However, there are other options.
>
> These three lines are at the bottom of the default wizard queries:
> out body;
> >;
> out skel qt;
>
> They basically mean "send back all the details of the selected objects and
> the geometry of their child objects" (the elements of the relations in most
> cases) This allows them to be displayed on the map. We can request that
> overpass sends us less data by changing these 3 lines. If you remove them,
> then you're requesting overpass to send you nothing, as you found out.
>
> There's 3 main useful options
> 1: Replace the 3 lines with "out center qt;" - This will display the centre
> of each townland rather than its boundaries
> 2: Replace the 3 lines with "out tags qt;" - This will show only the tags
> of the results, so they won't show up on the map. However, the map will
> still show how many objects were loaded, even though they don't appear.
> 3: Replace the 3 lines with "out ids qt;" - This will only show the ids of
> the results. As with 2, they won't show up on the map, but it will still
> show how many objects were loaded.
>
> Obviously, each approach has less and less data being transferred to the
> browser, making it easier to display it (and saving some network traffic).
> For example, using approach 3 on the query for Munster, the data is reduced
> from ~100Mb to <1 Mb, which is significant if you don't need to actually
> see the geometries of the queried items.
>
> Hope this helps,
> Mark
>
> On Wed, Nov 6, 2019 at 6:13 PM Brian Hollinshead
> wrote:
>
> > I often use this to count features, say locality=townland in Louth.
> >
> > Works fine but I tried it for Munster and 100mB was rather too much to
> > display. I removed the last three lines to avoid a display but then it
> does
> > not count.
> >
> > Perhaps one of you has a way around this please?
> >
> > I am also looking for a textual description of what constitutes
> traditional
> > Connamara, based perhaps on DEDs or Civil parishes etc. Does it
> correspond
> > with the new Connemara Municipal District?
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