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). Check http://picasaweb.google.com/lh/photo/x93nMda7mBrfra8AKbrj5g?feat=directlinkfor example. Now compare with the same area in potlach using the TMS: http://picasaweb.google.com/lh/photo/bHXkZ1jOB7v_JpiUmMlE5w?feat=directlink 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... Regards - Chris - How to load OS Street view tiles in Merkaartor: ------------------------------------------------------------------- - Be sure the .TIF files and the corresponding .TAB are in the same directory - "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) < ajrli...@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> > > JOSM: > > 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@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-gb >
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