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

Ryan Sommerville ryan.sommerville at gmail.com
Fri Feb 8 06:23:45 GMT 2013


Thanks for the response Maning!

We actually have a balloon and plan to fly it this week and for Open Data
Day on Feb 23rd. I'll be looking into tall buildings we can gain access to
in the dense, older areas, in the core of Kathmandu to put the balloon up
and see what we can get.


On 8 February 2013 11:54, maning sambale <emmanuel.sambale at gmail.com> wrote:

> There are opensource tools that can extract features from hires
> imagery, an example is GRASS, see this sample process (ignore the
> subjectline :))
>
> http://lists.osgeo.org/pipermail/grass-user/2007-August/040808.html
>
> 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:
>
> http://grassrootsmapping.org/
>
> 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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> >
>
>
>
> --
> cheers,
> maning
> ------------------------------------------------------
> "Freedom is still the most radical idea of all" -N.Branden
> wiki: http://esambale.wikispaces.com/
> blog: http://epsg4253.wordpress.com/
> ------------------------------------------------------
>
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