[Talk-GB] Mapping buildings with gables

Colin Smale colin.smale at xs4all.nl
Sat Apr 16 22:38:07 BST 2011


  I would say that a 2d representation of a 3d building should be its 2d 
bounding polygon, i.e. its projection onto the ground. This is what you 
see from vertically overhead (for above-ground buildings, and leaving 
out effects of parallax for the moment). So in this case it would show 
the straight-line edges of the gable and not the curved line of the wall 
at ground level.

If we were to map strictly only the situation at ground level, buildings 
which extend across roads would have to lose their "bridge" part which 
is bound to meet with objections. Underground buildings would disappear 
entirely.

Colin

On 16/04/2011 21:19, andrew wrote:
> Many houses in the London suburbs and elsewhere have polygonal or curved bays
> with square-ended gables above them. A typical example is:
>
> http://geographyphotos.photoshelter.com/gallery-image/Ipswich/G0000r5HlqvIzvDA/I0000AeFpmg6tFec
>
> 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?
>
> --
> Andrew
>
>
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