Subject: Re: [offtopic] acquiring Alaska data - msg#00034

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Re: [offtopic] acquiring Alaska data

great! Just remember the NED alaska data, is a little "special".... so if you need absolute accuracy, it may not be up to scratch. Cheers Joe Matt Wilkie wrote: > AHA, thanks to your help, I've figured out one can bypass the map > viewer altogether and put the coords on the URL like so: > > http://extract.cr.usgs.gov/Website/distreq/RequestSummary.jsp?AL=71.0,56.0,-140.0,-150.0&PL=NAK01HZ, > > > "AL=71.0,56.0,-140.0,-150.0" --> region of interest, > Lat-North,Lat-South Long-East,Long-West > > "PL=NAK01HZ" --> data set to choose from, in this case "National > Elevation Dataset Alaska (NED) 2 Arc Second" > > Now I just have to figure out what all the other secret codes are. > >> if want too you can go the asf route.... >> at ASF you might try contacting Rudi Gens.... > > I'll do that, thank you very much. >

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Re: [offtopic] acquiring Alaska data

On 3/8/07, Matt Wilkie <maphew-Re5JQEeQqe8AvxtiuMwx3w@xxxxxxxxxxxxxxxx> wrote: AHA, thanks to your help, I've figured out one can bypass the map viewer altogether and put the coords on the URL like so: http://extract.cr.usgs.gov/Website/distreq/RequestSummary.jsp?AL=71.0,56.0,-140.0,-150.0&PL=NAK01HZ, "AL=71.0,56.0,-140.0,-150.0" --> region of interest, Lat-North,Lat-South Long-East,Long-West "PL=NAK01HZ" --> data set to choose from, in this case "National Elevation Dataset Alaska (NED) 2 Arc Second" building on this, I've determined it's also possible to construct a URL to go straight to the extraction stage and use arbitrary area of interest extents. Looking at the html generated by the previous request, we can change the POST form to a GET request, which looks like this (needs to be all on one line to work): http://extract.cr.usgs.gov/diststatus/servlet/gov.usgs.edc.RequestStatus ?siz=87 &key=NAK &ras=1 &rsp=1 &pfm=ArcGRID &imsurl=-1 &ms=-1 &att=-1 &lay=-1 &fid=-1 &dlpre= &wmd=1 &mur=http%3A%2F%2Fextract.cr.usgs.gov%2Fdistmeta%2Fservlet%2Fgov.usgs.edc.MetaBuilder &mcd=NED &mdf=HTML &arc=ZIP &sde=ned.ak_ned &msd=NED.CONUS_NED_METADATA &zun=METERS &prj=0 &csx=5.55555555556E-4 &csy=5.55555555556E-4 &bnd= &bndnm= &RC=d9b131a2a5e3589013aaddb1d5f567585db594 &lft=-148.33333333333334 &rgt=-146.66666666666669 &top=63.0 &bot=59.0 for my purposes, it's these last four which are useful. Change them like so &lft=-143&rgt=-140&top=71.0&bot=59.0 and then each in turn: &lft=-147&rgt=-143&top=71.0&bot=59.0 &lft=-150&rgt=-147&top=71.0&bot=59.0 and I have my whole area of interest in three simple requests, plus there is no need go through the bother of mosaicking a bunch of little tiles together. It does take the server about 15 or 20 minutes to process each request though. I didn't attempt to find the maximum area, as my main goal is to get the data, not find the limits of their server and crash it. ;-) If you use this technique, please be gentle. It's not in our interests to force them to take protective measures and close this avenue. Thanks. -- -matt

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Re: [offtopic] acquiring Alaska data

great! Just remember the NED alaska data, is a little "special".... so if you need absolute accuracy, it may not be up to scratch. Cheers Joe Matt Wilkie wrote: > AHA, thanks to your help, I've figured out one can bypass the map > viewer altogether and put the coords on the URL like so: > > http://extract.cr.usgs.gov/Website/distreq/RequestSummary.jsp?AL=71.0,56.0,-140.0,-150.0&PL=NAK01HZ, > > > "AL=71.0,56.0,-140.0,-150.0" --> region of interest, > Lat-North,Lat-South Long-East,Long-West > > "PL=NAK01HZ" --> data set to choose from, in this case "National > Elevation Dataset Alaska (NED) 2 Arc Second" > > Now I just have to figure out what all the other secret codes are. > >> if want too you can go the asf route.... >> at ASF you might try contacting Rudi Gens.... > > I'll do that, thank you very much. >

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Re: [offtopic] acquiring Alaska data

On 3/9/07, John C. Tull <jctull-Re5JQEeQqe8AvxtiuMwx3w@xxxxxxxxxxxxxxxx> wrote: Also be sure to modify your request and have the data delivered as tar gzipped files (or whatever the alternative to zip is). Especially with the NEDs, I find that the directory structure gets all screwed up when they are unzipped from standard zip format. This is on a Mac, so it may be OS dependent. Just thought I would throw it out there. I didn't read your warning until I'd already downloaded everything. Happily I can report that on Windows both command line unzip from cygwin and with 7zip gui the archives extract properly. Having has many problems in the past with WinZip and the built-in zip support with Windows XP Explorer I didn't even try them. cheers, -- -matt