[Talk-GB] OS OpenData StreetView Tiles now available

Chris Browet cbro at semperpax.com
Wed Apr 7 09:45:29 BST 2010

I'm not too sure the reprojection from EPSG:27700 (OSGB36) to EPSG:900913
(Google) went perfect.

In Merkaartor, it is possible to load the OS Street View tiles directly and
to use the EPSG:27700 projection (see below).

Now compare with the same area in potlach using the TMS:

It seems the TMS is constantly shifted a couple of meters SE (this assuming
the OSM'ers are right, of course).

For clients supporting multiple projections, wouldn't it be best to have a
WMS (preferably a WMS-C) allowing to choose between the 2 projections (+
EPSG:4326, maybe)? It might be that
http://os.openstreetmap.org/wms/map.php?source=sv& allows it, but I can't
get the capabilities...

- Chris -

How to load OS Street view tiles in Merkaartor:
- Be sure the .TIF files and the corresponding .TAB are in the same
- "Layers" - "Map - ..." - "GeoTIFF" - "Load image..." and select the
tile(s) to load
- "Layers" - "Map - GeoTIFF" - "Zoom" to center on the tile

How to use the EPSG:27700 (OSGB36) projection in Merkaartor:
- if using svn trunk, just "View" - "Set projection" - "OSGB36 (EPSG:27700)"
- if using 0.15, first add the projection by going to
~/.merkaartor/Projections.xml and adding the following projection line:

> <Projection name="OSGB36 (EPSG:27700)">+proj=tmerc +lat_0=49 +lon_0=-2
> +k=0.999601 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36
> +no_defs</Projection>

On Wed, Apr 7, 2010 at 00:07, Andy Robinson (blackadder-lists) <
ajrlists at googlemail.com> wrote:

> The process of creating map tiles from Ordnance Survey StreetView in our
> required format is now largely complete (zoom 17 tiles not yet available)
> and can be viewed here:
> http://os.openstreetmap.org/
> These tiles can now be used as a backdrop in editors. However before you
> start editing, please consider the following:
> 1. Don't assume the OS data is either correct or up to date. Use it as a
> guide and additional resource for your mapping, not a replacement.
> 2. Please add source tags to any data you add to OSM from OS StreetView.
> See
> the tag suggestions:
> http://wiki.openstreetmap.org/wiki/Ordnance_Survey_Opendata#Attributing_OS
> 3. If you're tempted to map in an area you're not familiar with, contact
> any
> local contributors first. Please don't alienate other contributors by
> treading on their toes. They will know their local area better than anyone
> else.
> 4. Look for places that have been mapped using Yahoo! imagery and don't
> have
> road names. This is a good place to start.
> 5. Avoid simply duplicating OS data in blank areas of OSM unless you're
> familiar with the area and don't have access to other resources such as a
> GPS.
> 6. In May the OS will release a further vector based product which may
> provide better data for buildings than tracing from OS StreetView. You
> might
> want to hold off tracing buildings until the details are confirmed.
> How to make use of these tiles:
> Potlatch:
> When the next version of Potlatch is live, you can just select 'UK: OS
> StreetView' from the background menu in the options box.
> Until then, just add this custom URL:
> http://os.openstreetmap.org/sv/!/!/!.png<http://os.openstreetmap.org/sv/%21/%21/%21.png>
> Create a new WMS layer with the following url:
> http://os.openstreetmap.org/wms/map.php?source=sv&
> or alternatively use the SlippyMap plugin for which you can find
> instructions of how to add custom tile sources at
> http://wiki.openstreetmap.org/wiki/JOSM/Plugins/SlippyMap#Custom_tile_URLS
> with http://os.openstreetmap.org/sv/ as slippymap.custom_tile_source_1.url
> Merkaartor:
> 1) In the Tools menu, open the TMS Servers Editor.
> 2) Add the following:
> Name: OS Street View
> Server address: os.openstreetmap.org
> Path: /sv/%1/%2/%3.png
> Tile size: 256
> Minimum zoom: 6
> Maximum zoom: 16
> Hit 'apply' and add the new TMS to a map layer.
> You can find out more about the OS OpenData products on the OSM wiki here:
> http://wiki.openstreetmap.org/wiki/Ordnance_Survey_Opendata
> And finally a vote of thanks to all those at the OS, past and present, who
> created the data originally and to the OSM folks who have worked hard over
> the last few days to create the tiles, especially Grant, Richard, Thomas
> and
> TomH. Apologies if I have missed anyone out.
> Cheers
> Andy
> _______________________________________________
> Talk-GB mailing list
> Talk-GB at openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-gb
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