[OSM-talk] protocol for adding buildings using aerial imagery?

[charlie at cferrero.net]

Erin Korris (ekorris at yahoo.com) wrote:

> Hello:
>
> I am wondering if there is a rule to follow when tracing buildings  
> using aerial
> imagery.  On the default, Yahoo imagery, the buildings are slightly  
> displaced so
> in addition to the roof you can see the foundation of certain sides of the
> building.  Should this be ignored and the building drawn based on the roof?
>
> Thanks
>
>
>
This is a major issue when tracing tower blocks - the taller the  
building the more the roof appears to be displaced relative to the  
floor due to the perspective of the plane taking the photos.  I have  
always tried to map the base because, ultimately, a map is a  
representation of what's at ground-level.  If you mapped roofs you'd  
get very tall buildings overlapping the surrounding roads.


-- 
Charlie