Hi John, Landslide is one of the major issues. We can try to use local knowledge for groundtruthing.
Nama On Sun, May 10, 2015 at 6:34 AM, john o'l <[email protected]> wrote: > I've been focusing on landslides and have located several score that > appear recent. Of these, a few are pre-quake and appear relatively stable, > some are pre-quake but appear reactivated and many appear to have been > associated with the quake and/or aftershocks. I've mapped several dozen of > these so far. In my next email, I'll cover why you won't find them in > osm... yet. For this one, I'd like to stick to post quake imagery and some > of its quirks. > > There is an inhabited hillside that had numerous landslides, some predate > the quake, but most are presumably related. So far I've mapped about half > of them, those that are largest or appear to threaten buildings and > pathways. There is Digital Globe imagery available from May 3 and May 8. It > looks like QGIS easily operates with more than one coordinate system at a > time. The center of a large boulder in the May 3 imagery (Longitude, > Latitude; WGS84 EPSG:3857 x,y) is at > 85.85659,27.83609;9557511.789,3228324.329, in the May 8 imagery it is at > 85.85669,27.83656;9557522.728,3228382.865. Mind you, this is not a > complaint, rather it is a concrete example of the variability with this > recent imagery. > > A more extreme example is a slide that appeared to be partially blocking a > stream in the May 3 imagery 85.90258,27.87818;9562631.312,3233623.303; -- > it was completely obscured by a hillside in the May 8 imagery (probably > taken from a more northerly or northwesterly vantage point.) > > Downslope (westward) from a likely reactivated slide located at > 85.81987,27.90810;9553423.739,3237391.771 is a remote area that appears > very hard hit. The May 8th imagery is mostly clouds, but the May 3rd > imagery shows a blue rooftop at 85.80644,27.90818;9551929.301,3237402.414, > it looks like there are several large boulders in the immediate area and > there is not much left to tell there were more than 20 buildings nearby. > While the boulders may have contributed, at the moment I think it is > probable that the shaking itself was mostly responsible for the extreme > level of destruction. > > One advantage of different acquisition angles is that some features may be > discernible on slopes that don't ordinarily show up very well. > > Question to the HOT folks -- is there a way to specify the date of DG > imagery we access through the proxy server?, Some of the May 8 imagery is > starting to come up over the May 3 imagery without me telling it to. > > Best regards, > > John > > _______________________________________________ > HOT mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/hot > > -- ________________________________________________________________________ Nama R. Budhathoki, Ph.D. Executive Director, Kathmandu Living Labs *(www.kathmandulivinglabs.org <http://www.kathmandulivinglabs.org>)* Cell: 977-9803571739 Office: 977-6205000
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