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On 18/03/2011 22:56, Kev js1982 wrote:
<blockquote
cite="mid:AANLkTi=Ma+a4UWav7VjYkJAtdBWan7K_8oO1NU=A8aao@mail.gmail.com"
type="cite">Resurrecting an old thread I know but with the NSPD
Open data also being available allowing Northern Ireland to be
generated and having access to an otherwise idle 64bit server I've
taken the opportunity to revisit this, and have successfully
created the shapefiles (it only took the server 12 days to
generate the blighters - it managed to generate Z16 tiles for the
whole of Europe and Z18 for the British Isles in just 36 hours -
meh!) but now have one more obstacle to overcome...<br>
<br>
The Veroni thingy obviously generates the tiles so they butt up
against one another which works perfectly here in the landlocked
East Midlands, but goes somewhat wrong in coastal areas (Fig 1).<br>
<br>
My thought here is that the "World Boundaries" shape file can be
used to trim the coastal boundaries to be locked to land so that
the map looks "nice" (i.e. postcodes don't end up in the sea save
for a little overlap on beaches) - Indeed if you add the World
Boundaries file to Quantum GIS and use the "Clip Tool" you end up
with what visually looks correct ( Fig. 3) but if you then hide
the World Boundaries file the problem becomes obvious (Fig 2.) <br>
<br>
What I want to know, is it possible to trim the postcode shapes so
that nothing outside another set of shapes (i.e. the British Isles
landmass) is included, but instead of leaving gaps the postcode
shapes (e.g. FY3 1) are adjusted so that the line runs along the
coast line? i.e. I would be left with something visually the same
as Fig. 3 but with the coastlines part of the NNXX-X shapefile
layer, and more specifically the correct polygon (e.g. the FY3 1
polygon).<br>
<br>
Kev<br>
<br>
<br>
Fig 1 - Postcode areas in south west Lancashire and the north
Wales coast (green = NNXX-X shapefile, blackline and dotted area
uses the worldboundaries file)<br>
<a moz-do-not-send="true"
href="http://kjs.me.uk/3rdparty/osm/SouthWestLancs-NNXX-X.png">http://kjs.me.uk/3rdparty/osm/SouthWestLancs-NNXX-X.png</a><br>
<br>
Fig 2 - After using Quantum GIS's "Clip" tool - <a
moz-do-not-send="true"
href="http://kjs.me.uk/3rdparty/osm/SouthWestLancs-NNXX-X_trimmed.png">http://kjs.me.uk/3rdparty/osm/SouthWestLancs-NNXX-X_trimmed.png</a><br>
<br>
Fig 3 - After adding the "World Boundaries" back on. -
SouthWestLancs-NNXX-X_trimmed_withwb.png<br>
<br>
<i>Open Street Map data licenced under the <a
moz-do-not-send="true"
href="http://creativecommons.org/licenses/by-sa/2.0/">Creative
Commons Attribution-Share Alike 2.0 license</a> by the <a
moz-do-not-send="true" href="http://openstreetmap.org/">OpenStreetMap</a></i>
project and its contributors. <i>Maps contain <a
moz-do-not-send="true"
href="http://www.ordnancesurvey.co.uk/oswebsite/opendata/">Ordnance
Survey OpenData</a> © Crown copyright and database right 2010.</i>
<i>Postcode data in Great Britain is provided by Code-Point Open
which contains Royal Mail data © Royal Mail copyright and
database right 2010.</i> <i>Postcode data in Northern Ireland
is from the <a moz-do-not-send="true"
href="http://www.ons.gov.uk/about-statistics/geography/products/geog-products-postcode/nspd/">NSPD
Open</a> which contains National Statistics data © Crown
copyright and database right 2010. </i><br>
<br>
<div class="gmail_quote">On Fri, Apr 30, 2010 at 12:30, Kev js1982
<span dir="ltr"><<a moz-do-not-send="true"
href="mailto:osm@kevswindells.eu">osm@kevswindells.eu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt
0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
Hi Dave,<br>
<br>
Thanks for providing the shapefiles for download - they did
the job nicely.<br>
<br>
One thing I have noticed (which also afflicts <a
moz-do-not-send="true"
href="http://random.dev.openstreetmap.org" target="_blank">random.dev.openstreetmap.org</a>)
is that a few postcode area/districts are missing - namely<br>
<br>
FY2 - (North Shore) Blackpool, Lancs<br>
PE11 - Spalding, Lincs<br>
PL17 - Callington, Cornwall<br>
<br>
Using the code point download (which I got via the MySociety
mirror) shows that these postcodes do exist.<br>
<br>
Also one of the AB ones (12 or 21 IIRC) for some reason
includes parts of Éire, Spain, Portugal and atlantic; while HS
includes Reykjavik<br>
<br>
Just thought you'd like to know there is a possible error with
the conversion process.<br>
<br>
Nice work though - been after a postcode map for a while, and
to go from an A5 diagram to full "google maps" goodness in one
swoop is awesome!<br>
<br>
Regards<br>
<br>
Kev Swindells.
<div>
<div class="h5">
<br>
<br>
<div class="gmail_quote">
On Mon, Apr 26, 2010 at 5:29 PM, Dave Stubbs <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:dave@randomjunk.co.uk" target="_blank">dave@randomjunk.co.uk</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt
0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204);
padding-left: 1ex;">
<div>
<div>On Mon, Apr 26, 2010 at 5:15 PM, Kev js1982
<<a moz-do-not-send="true"
href="mailto:osm@kevswindells.eu"
target="_blank">osm@kevswindells.eu</a>>
wrote:<br>
> On Mon, Apr 26, 2010 at 5:00 PM, Kev js1982
<<a moz-do-not-send="true"
href="mailto:osm@kevswindells.eu"
target="_blank">osm@kevswindells.eu</a>>
wrote:<br>
>><br>
>> Thanks for that Dave - really useful.<br>
>><br>
>> One question though - which prj
string/file do I need for these?<br>
>><br>
><br>
> Answering my own question - looks to be
Google Mercator.<br>
><br>
> <a moz-do-not-send="true"
href="http://spatialreference.org/ref/sr-org/6627/"
target="_blank">http://spatialreference.org/ref/sr-org/6627/</a><br>
><br>
> Kev Swindells<br>
><br>
><br>
<br>
</div>
</div>
Actually, for some obscure historical reason it's
projected into<br>
"+proj=merc" which is srs 3395.<br>
<br>
Close to 900913, but not quite the same -- my mapnik
stylesheet is<br>
then set to reproject to google mercator for the tile
generation.<br>
<font color="#888888"><br>
Dave<br>
</font></blockquote>
</div>
<br>
</div>
</div>
</blockquote>
</div>
<br>
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</blockquote>
You ought to be able to do this with Intersect first which will
divide your FY3 1 polygon into two along the coastline & then
clip the result to only get the ones inside the coastline. At least
if I understand the problem correctly.<br>
<br>
I've never got the packaged Voronoi working so have only played with
Delauney triangulation doing the same process.<br>
<br>
Jerry<br>
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