[Talk-GB] OS OpenData StreetView Tiles now available

Andy Robinson (blackadder-lists) ajrlists at googlemail.com
Wed Apr 7 10:48:07 BST 2010

Chris Browet wrote:
>Sent: 07 April 2010 9:45 AM
>To: talk-gb at openstreetmap.org
>Cc: Merkaartor mailing list
>Subject: Re: [Talk-GB] OS OpenData StreetView Tiles now available
>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).
>for example.
>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).

As a point of note while I was just doing a little test editing with these
tiles, using the WMS function in JOSM I wasn't getting the necessary quality
to read the street names, even with a change resolution request, so I
swapped out to the slippy map viewer which was much better though I'm not
convinced either method gets tile placement exactly right.

Perhaps someone could do some comparative data checking using a few well
established and surveyed ground points, like the OSGB static stations
perhaps for which OS publish the co-ords? Just a thought.



>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
>- 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
>2 +k=0.999601 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36
>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
>	required format is now largely complete (zoom 17 tiles not yet
>	and can be viewed here:
>	http://os.openstreetmap.org/
>	These tiles can now be used as a backdrop in editors. However before
>	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:
>	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
>	treading on their toes. They will know their local area better than
>	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
>	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
>	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:
>	StreetView' from the background menu in the options box.
>	Until then, just add this custom URL:
>	http://os.openstreetmap.org/sv/!/!/!.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
>	with http://os.openstreetmap.org/sv/ as
>	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
>	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
>	the last few days to create the tiles, especially Grant, Richard,
>Thomas and
>	TomH. Apologies if I have missed anyone out.
>	Cheers
>	Andy
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