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?
> ___
> 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
