[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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