[HOT] landslides and imagery

Springfield Harrison stellargps at gmail.com
Sun May 10 06:05:26 UTC 2015

Hello John,

With reference to your moving boulder, just 
wondering if that could be in fact moving, i.e., 
not an image based coordinate shift as such.  I'm 
just thinking that with aftershocks and general 
instability, many of these new features are still 
sorting themselves out and traveling downhill.

Can DG or Bing make stereo pairs 
available?  Likely a long shot, but thought I would ask.

                 Cheers . . . . . . . . Spring Harrison

At 09-05-2015 17:49 Saturday, john o'l 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.Â
>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. Â
>A more extreme example is a slide that appeared 
>to be partially blocking a stream in the May 3 
>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.)Â
>Downslope (westward) from a likely reactivated 
>slide located at 
>85.81987,27.90810;9553423.739,3237391.771 Â 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.Â
>One advantage of different acquisition angles is 
>that some features may be discernible on slopes 
>that don't ordinarily show up very well.Â
>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. Â
>Best regards,
>HOT mailing list HOT at openstreetmap.org 

More information about the HOT mailing list