Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal
> I imagine any proposed import would run into similar issues, particularly >since the> imagery in Nepal is likely not as good as the multispectral+lidar >that > vtcraghead had. Yes, but also consider other ways of using this LIDAR data. LIDAR, with aerial imagery, could be another useful source for manual editing. Imagine a tasking manager job, that included lidar derived tiles, in order to map rough building height. -Mikel * Mikel Maron * +14152835207 @mikel s:mikelmaron > > From: Paul Norman >To: 'maning sambale' ; 'Ryan Sommerville' > >Cc: hot@openstreetmap.org >Sent: Friday, February 8, 2013 2:38 AM >Subject: Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, >Nepal > >> From: maning sambale [mailto:emmanuel.samb...@gmail.com] >> Subject: Re: [HOT] Advice tracing footprints with poor imagery in >> Kathmandu, Nepal >> >> 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. > >The last time someone proposed importing automatically generated building >outlines[1] the consensus was against it. They used multispectral imagery >and LIDAR coverage and there were still significant concerns about the >quality. One of the basic problems with automatic building detection is that >buildings tend to consist of right angles but automatic detection methods >tend be better with irregularly shaped areas like tree coverage. I imagine >any proposed import would run into similar issues, particularly since the >imagery in Nepal is likely not as good as the multispectral+lidar that >vtcraghead had. > >[1]: http://lists.openstreetmap.org/pipermail/imports/2012-March/001267.html > > >___ >HOT mailing list >HOT@openstreetmap.org >http://lists.openstreetmap.org/listinfo/hot > > >___ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal
> From: maning sambale [mailto:emmanuel.samb...@gmail.com] > Subject: Re: [HOT] Advice tracing footprints with poor imagery in > Kathmandu, Nepal > > 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. The last time someone proposed importing automatically generated building outlines[1] the consensus was against it. They used multispectral imagery and LIDAR coverage and there were still significant concerns about the quality. One of the basic problems with automatic building detection is that buildings tend to consist of right angles but automatic detection methods tend be better with irregularly shaped areas like tree coverage. I imagine any proposed import would run into similar issues, particularly since the imagery in Nepal is likely not as good as the multispectral+lidar that vtcraghead had. [1]: http://lists.openstreetmap.org/pipermail/imports/2012-March/001267.html ___ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal
Hi Ryan, I'm with Maning I think you will actually have better success doing the whole process manually. Also there is the issue of being able to do the automated extraction with Bing. I think if you were to do the automated extraction and then ask people to fill in you would be less likely to get people to help. It can be frustrating to add buildings when people have already added some of them, it doesn't allow one to go systematically through each square. What type of methodology are you looking for? I would suggest assigning squares to people to do the tracing and then printing out walking papers for field surveys to add the additionally attributes. It might make sense to have two tasks. The first for everyone just to trace the buildings and the 2nd for adding the attributes for the sake of tracking. Actually having a couple different tasks in general might be good. If you were to start in one area you could correct your methods based on what you learn from the first area to extend to the 2nd. I would recommend having people that are better mappers on your team look over the data very early on and correct mistakes. This will help improve the later collected data. Using the building plugin tool is really helpful. Also using features in JOSM such as orthogonalize shape will improve your results. One other thing to keep in mind is what analysis you are trying to do at the end. Meaning I would think it is more important to get an accurate count of the buildings and general size than make it exact. You will still get a pretty good model of what would happen after an earthquake. Best, -Kate On Fri, Feb 8, 2013 at 1:09 PM, maning sambale 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 > 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 >> >> ___ >> HOT mailing list >> HOT@openstreetmap.org >> http://lists.openstreetmap.org/listinfo/hot >> > > > > -- > cheers, > maning > -- > "Freedom is still the most radical idea of all" -N.Branden > wiki: http://esambale.wikispaces.com/ > blog: http://epsg4253.wordpress.com/ > -- > > ___ > HOT mailing list > HOT@openstreetmap.org > http://lists.openstreetmap.org/listinfo/hot ___ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal
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 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 > 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 > > > > ___ > > HOT mailing list > > HOT@openstreetmap.org > > http://lists.openstreetmap.org/listinfo/hot > > > > > > -- > cheers, > maning > -- > "Freedom is still the most radical idea of all" -N.Branden > wiki: http://esambale.wikispaces.com/ > blog: http://epsg4253.wordpress.com/ > -- > ___ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal
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 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 > > ___ > HOT mailing list > HOT@openstreetmap.org > http://lists.openstreetmap.org/listinfo/hot > -- cheers, maning -- "Freedom is still the most radical idea of all" -N.Branden wiki: http://esambale.wikispaces.com/ blog: http://epsg4253.wordpress.com/ -- ___ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
[HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal
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 ___ HOT mailing list HOT@openstreetmap.org http://lists.openstreetmap.org/listinfo/hot
