[Talk-GB] Mapping buildings with gables

Ed Avis eda at waniasset.com
Sat Apr 16 21:55:29 BST 2011

andrew <andrewhainosm at ...> writes:

>Should we be mapping the outline of the gable because it is the greatest extent
>of the building, the bay because it is the important bit or a straight line
>because the bay and gable are too small to map sensibly?

I think technically you should map what's at ground level.  The building has an
'implicit' layer=0 which implies ground level.  But this is a pretty weak
argument; a stronger precedent would be to see what other mapping providers such
as the Ordnance Survey do.  I believe OS shows ground level but I'm not sure.

In practice map whatever you can see clearly the aerial photo.  Even with the
Bing imagery we cannot clearly see the roof of the building distinct from its
ground floor walls.  Beggars can't be choosers.

Sometimes I elaborately trace the building outline; sometimes I map a whole
terrace of houses as mere rectangles.  It depends on how good the Bing imagery is
in that area and what else is nearby to be mapped.

Ed Avis <eda at waniasset.com>

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