<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>> </span><span style="color: rgb(69, 69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px;"> </span><span style="color: rgb(69, 69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px;">I imagine </span><span style="color: rgb(69, 69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px;">any proposed import would run into similar issues, particularly since the</span></div><span style="color: rgb(69, 69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px;">> imagery in Nepal is likely not as good as the multispectral+lidar that</span><br style="color: rgb(69, 69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px;"><span style="color: rgb(69, 69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px;">> vtcraghead
had.</span><div></div><div> </div><div>Yes, but also consider other ways of using this LIDAR data.</div><div>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.</div><div><br></div><div>-Mikel</div><div><br></div><div>* Mikel Maron * +14152835207 @mikel s:mikelmaron<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; margin-top: 5px; padding-left: 5px;"> <div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"> <div style="font-family: 'times new roman', 'new york', times, serif; font-size: 12pt;"> <div dir="ltr"> <font size="2" face="Arial"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Paul Norman <penorman@mac.com><br> <b><span style="font-weight: bold;">To:</span></b> 'maning sambale' <emmanuel.sambale@gmail.com>;
'Ryan Sommerville' <ryan.sommerville@gmail.com> <br><b><span style="font-weight: bold;">Cc:</span></b> hot@openstreetmap.org <br> <b><span style="font-weight: bold;">Sent:</span></b> Friday, February 8, 2013 2:38 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [HOT] Advice tracing footprints with poor imagery in Kathmandu, Nepal<br> </font> </div> <br>
> From: maning sambale [mailto:<a ymailto="mailto:emmanuel.sambale@gmail.com" href="mailto:emmanuel.sambale@gmail.com">emmanuel.sambale@gmail.com</a>]<br>> Subject: Re: [HOT] Advice tracing footprints with poor imagery in<br>> Kathmandu, Nepal<br>> <br>> There are opensource tools that can extract features from hires imagery,<br>> an example is GRASS, see this sample process (ignore the subjectline :))<br>> <br>> http://lists.osgeo.org/pipermail/grass-user/2007-August/040808.html<br>> <br>> But this requires, that you have direct access to the imagery (which<br>> isn't legally allowed with Bing)<br>> <br>> Another option for small areas is to try balloon/kite mapping:<br>> <br>> http://grassrootsmapping.org/<br>> <br>> In my experience, the most effective way is by manually tracing in JOSM<br>> (no computer algorithm can do what a human can see, at least not<br>> yet) and of course ground
validation.<br><br>The last time someone proposed importing automatically generated building<br>outlines[1] the consensus was against it. They used multispectral imagery<br>and LIDAR coverage and there were still significant concerns about the<br>quality. One of the basic problems with automatic building detection is that<br>buildings tend to consist of right angles but automatic detection methods<br>tend be better with irregularly shaped areas like tree coverage. I imagine<br>any proposed import would run into similar issues, particularly since the<br>imagery in Nepal is likely not as good as the multispectral+lidar that<br>vtcraghead had.<br><br>[1]: http://lists.openstreetmap.org/pipermail/imports/2012-March/001267.html<br><br><br>_______________________________________________<br>HOT mailing list<br><a ymailto="mailto:HOT@openstreetmap.org"
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