[Talk-GB] OS VectorMap District road files for Devon and Cornwall

mick bareman at tpg.com.au
Mon Feb 6 01:35:53 GMT 2012


On Sun, 05 Feb 2012 16:38:11 +0000
Richard Fairhurst <richard at systemeD.net> wrote:

> Hi all,
> 
> In order to assist remapping in the South-West, I've uploaded a bunch of 
> OS-derived shapefiles each containing all the roads in a 10km x 10km 
> area. You can use Potlatch 2 to bring these geometries into the map, 
> saving tracing work.
> 
> To load:
> 
> 1. Open Potlatch 2 at the required area.
> 2. Click 'Background' -> 'Vector file...'.
> 3. In the text box at the bottom, paste a URL of the form:
> 	http://richard.dev.openstreetmap.org/os/SS20_Road.shp
> 4. Untick 'Simplify paths' and make sure 'Shapefile' and 'Lat/long' are 
> selected.
> 5. Click 'Load'.
> 6. When the newly loaded layer appears in the table above, change the 
> style from 'Potlatch' to 'GPS' (more visible)
> 7. Close the dialogue
> 
> Then, to bring a road through, just alt-click it. You will (obviously) 
> need to edit the tags (use Advanced mode) and add connections with other 
> roads (the J key is good for this).
> 
> Each 10km x 10km square is a different shapefile. To find the URL, go to:
> 	http://geowiki.com/os.cgi
> and type the placename, then just copy and paste the URL it suggests.
> 
> I've uploaded road shapefiles for the SS, SW and SX grid areas. If you 
> would like a different area or another layer (e.g. rivers), let me know, 
> though it might take a while. Alternatively, I've provided instructions 
> at the bottom as to how to do it yourself.
> 
> There is lots that could be improved about this workflow: implementing 
> TagTransform to remap tags automatically, zipping up shape-files, 
> allowing Ctrl with alt-click, automatically joining streets, etc. I'm 
> very very unlikely to have much time to do this before 1st April, so 
> with the best will in the world, it's not worth making "this would be 
> easier if..." suggestions unless they're really astonishingly simple - 
> sorry. More P2 coders always welcome. :)
> 
> This is provided as a service for remapping only. It will on balance 
> improve the quality of the mapping in the South-West, but is obviously 
> not as good as survey. Some notes on the data:
> 
> - VMD has downsampled road geometries which are of a better standard 
> than the NPE-traced mapping in large parts of the South-West, but are 
> not as good as the best OSM work.
> - VMD roads are broken at every junction. This makes them more suitable 
> for country lanes than town mapping. Also, some very dense areas (e.g. 
> Plymouth) are probably still too large for P2 to manage sensibly. (Plus, 
> in my experience, dev.osm.org is not great at serving huge files.)
> - Names are only present for 'Minor Roads' and upwards, _not_ for 'Local 
> Streets'.
> - VMD is subject to the usual OS OpenData licence.
> 
> cheers
> Richard
> 
> 
> 
> 
> 
> == How to create the shapefiles yourself ==
> 
> We need to split the shapefiles into 10km x 10km 'tiles' as 100km x 
> 100km boggles P2 in busy areas.
> 
> Download the 100km x 100km VMD shapefiles from the OS OpenData website. 
> Make sure you have gdal/ogr2ogr installed. Then, create each 10km x 10km 
> tile like this:
> 
> ogr2ogr -clipsrc 290000 90000 299999 99999 -s_srs EPSG:27700 -t_srs 
> EPSG:4326 -skipfailures SX99_Road.shp SX_Road.shp
> 
> In other words: "clip to this bounding box, reproject from OSGB to 
> lat/long, write to SX99_Road.shp, read from SX_road.shp". (Yes, ogr2ogr 
> does take destination and source files the wrong way round.) You can 
> fairly trivially put a loop around this to produce all 100 tiles.
> 
> Upload the resulting .shp, .shx and .dbf to your webspace. (P2 doesn't 
> read .prj files so you can ignore those.) Put a crossdomain.xml at the 
> root of it (you can copy the one from 
> http://richard.dev.openstreetmap.org/crossdomain.xml) to tell Flash that 
> yes, it is allowed to read files from there.
> 
A possible alternative to the bounding box procedure would be to obtain pre 2010 datasets, they were published in the 100th sheet format, e.g. SS00 to SS99. I have a copy of the England set I could contribute a copy of.

mick



More information about the Talk-GB mailing list