[Talk-GB] OS OpenData StreetView Tiles now available

Chris Browet cbro at semperpax.com
Wed Apr 7 12:39:16 BST 2010

On Wed, Apr 7, 2010 at 12:42, Richard Fairhurst <richard at systemed.net>wrote:

> Chris Browet wrote:
> > I'm not too sure the reprojection from EPSG:27700 (OSGB36) to
> > EPSG:900913 (Google) went perfect.
> If you're tracing from _any_ source without first aligning it with a
> trustworthy ground reference (typically an average of existing GPS
> tracks), You're Doing It Wrong.

Ok, but let's be practical.
Same goes for every GPS traces used to create OSM. There should be many for
the same road, then averaged, etc... I'm not sure there is a large
percentage of OSM data meeting these criterias...

Re tracing, you cannot deduce the projection (especially a tricky one like
OSGB36) by aligning a number of points. If the base projection is wrong and
a simple translation do not solve the problem, then you're roasted...

Did you do the aligning exercise to check the validity of the OS Street View
tiles (in EPSG:27700) and the reprojected ones (in EPSG:900913)?

- Chris -
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