[HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal

maning sambale emmanuel.sambale at gmail.com
Fri Feb 8 06:09:23 GMT 2013

There are opensource tools that can extract features from hires
imagery, an example is GRASS, see this sample process (ignore the
subjectline :))


But this requires, that you have direct access to the imagery (which
isn't legally allowed with Bing)

Another option for small areas is to try balloon/kite mapping:


In my experience, the most effective way is by manually tracing in
JOSM (no computer algorithm can do what a human can see, at least not
yet) and of course ground validation.

On Fri, Feb 8, 2013 at 1:51 PM, Ryan Sommerville
<ryan.sommerville at gmail.com> wrote:
> Hi all,
>      We're working on digitizing all building footprints in the Kathmandy
> Valley. The current Bing imagery makes this a challenge in some areas,
> especially densely packed neighborhoods.
> If possible, we'll utilize an automatic extraction of footprints and are
> working on this now along with specific validation of that extraction. This
> will still leave many buildings untraced (especially in dense neighborhoods)
> so we'll also need to manually trace many buildings. The imagery sometimes
> shows a clear building boundary but often it is unclear.
> Does anyone know of a methodology to accurately trace footprints using low
> resolution imagery through a combination of mapping technique and
> validation?
> Is it possible to add to the Buildings_Tools plugin to tag traces which will
> require field verification?
> Any advice or suggestions is much appreciated!
> Thanks,
> Ryan
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