[Talk-GB] Composite mapping (OSM and OS, PRoWs etc)
sk53.osm at gmail.com
Tue Sep 6 18:10:36 UTC 2016
I have done this on an *ad hoc* basis using QGIS but have never managed to
transfer the process successfully to PostGIS.
I think Nick Whitlegg does this for his Android walking app with coverage
of several counties in Southern England.
It's fundamentally much easier to show the difference than to convert that
into suitable file formats (see the recent blog post about missing roads in
Brazil which describes exactly this issue).
FWIW. What I do is :
- Pull in the whole highway network from OSM
- Buffer it by some magic number (10-25 metres)
- Find all PRoWs which are within the buffers.
- Repeat on last dataset for highways with designation tag.
Then one wants to do differences between all PROWS and PROWS matched to OSM
& those lines and ones matched on designation.
I have a very crude mkgmap script which takes the output and draws thick
lines in various colours as a transparent overlay for a Garmin device.
With PostGIS I have run into various problems including non-noded
intersection errors in the latter steps. So I have never automated the
process. However, for smallish data sets, e.g., all paths within 5-10 miles
of a centroid (one can use Overpass to grab the data) it's quick enough to
run the evening before venturing out.
On 6 September 2016 at 18:46, Robert Whittaker (OSM lists) <
robert.whittaker+osm at gmail.com> wrote:
> On 6 September 2016 at 18:22, Dave F <davefoxfac63 at btinternet.com> wrote:
> > As a by-product of the PROW comparison, would it be possible to create a
> > list (Geojson?) of paths not in OSM but in LA's definitive maps? It's
> I don't know if you've seen it, but I've had a go at developing a
> comparison tool for PRoWs myself:
> The tool currently only covers Norfolk and Suffolk, but it could be
> extended further afield if suitably licensed and formatted data is
> available. There are also several missing features (in particular the
> ability for anyone other than me to update the mapping completion
> status of each route in the tool). But hopefully it's still useful to
> people in it's current state. Other suggestions for improvements would
> be welcome.
> Robert Whittaker
> Talk-GB mailing list
> Talk-GB at openstreetmap.org
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