[OSM-dev] [Talk-GB] OSM augmented reality project - affordable hosting recommendations or Overpass?

[Nick Whitelegg]

Hello everyone,


Thanks for the suggestions. I've had an offer of hosting (many thanks!) but it's good to know what options are available.

Roland - thanks for the info on Overpass. Am aware that GeoJSON isn't supposed to be epsg:3857 but I do it that way as it saves a reprojection stage.


Thank,s

Nick


________________________________
From: Roland Olbricht <roland.olbricht at gmx.de>
Sent: 05 February 2019 16:59:48
To: Nick Whitelegg; dev at openstreetmap.org; talk-gb at openstreetmap.org
Subject: Re: [Talk-GB] OSM augmented reality project - affordable hosting recommendations or Overpass?

Hi,

> As an alternative, I was wondering how acceptable it would be to use the
> Overpass API to obtain the data? Downloaded data would be cached on the
> device so for a given area, data would only need to be downloaded once.

I'm fine with such a usage. The fine print is about other issues:

- Overpass API does support GeoJSON indirectly, but GeoJSON does not
support EPSG:3857, see
https://tools.ietf.org/html/rfc7946#section-4

To get GeoJSON I suggest

[out:json];
way(south,west,north,east)[highway];
convert link ::=::,::geom=geom();
out geom;

where (south,west,north,east) is the bounding box.

As an act of courtesy I suggest to set the "Accept-Encoding: deflate,
gzip" header and use

[out:json];
way(south,west,north,east)[highway];
if (count(ways) < 20000)
{
   convert link ::=::,::geom=geom();
   out geom;
}
else
{
   make error what="Too many ways in this bounding box";
   out;
}

This compresses the data and bails out if there are more than 20000 ways
in the bounding box, corresponding to between 1 MB and 2 MB of data.
Overpass would happily deliver about 1 GB per user and day, but the
users may have data plans with rather 1 GB per month.

Thanks,
Roland
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