Downloading NED data

[ibycus]

So, am I correct in assuming you're downloading all the data off the Seemless server manually? (no batching?).

Anyone looked at batching it?
Anyone know if it violates their license agreement? (I couldn't see anything, but if someone has tried and been banned, I don't want to try).
Anyone have more details of the format of the URLs?
I know that this:
http://extract.cr.usgs.gov/Website/distreq/RequestSummary.jsp?AL=30.5,30,-88,-89&PL=ND301HZ,

Retrieves a listing of all the data within that bounding box, generally split in to a number of individual files

If you add &CS=250 to the URL you can get them as one file. Modifying the PL= value changes the format or the product you're looking to download.

You can go direct to the download page with
http://extract.cr.usgs.gov/diststatus/servlet/gov.usgs.edc.RequestStatus?siz=58&key=ND3&ras=1&rsp=1&pfm=GridFloat&imsurl=-1&ms=-1&att=-1&lay=-1&fid=-1&dlpre=&lft=-86.0&rgt=-85.75&top=33.5&bot=33.0&wmd=1&mur=http%3A%2F%2Fextract.cr.usgs.gov%2Fdistmeta%2Fservlet%2Fgov.usgs.edc.MetaBuilder&mcd=NED13&mdf=HTML&arc=ZIP&sde=NED.conus_ned_13e&msd=NED.CONUS_NED_13_METADATA&zun=METERS&prj=0&csx=9.259259260000041E-5&csy=9.259259260000041E-5&bnd=&bndnm=&RC=49bd874d86e654d1446be822b3a27a1ad16187ee

Where lft, rgt, top, bot refer to the left, right, top and bottom.
arc is obviously the ARChive format.
siz= is the "Size" in megabytes of the file
mdf = metadata format
key =???
RC = Some kind of UID? Can be left blank, but must be submitted
zun = Z Units (must be meters?)
csx= X grid spacing
csy = Y grid spacing
bnd = ?
bndnum = ?

All fields seem to be required, but have some flexibility as far as the input data (don't know if this changes the output data)

[-Oz-]

Did you ever try making it one file rather than the 4?

I read all the licenses I could find and didn't find anything that said it wasn't legit.

[John]

Another resource for the NED data is http://datagateway.nrcs.usda.gov/ with a 4GB max you can download a state at a time of the 30 Meter data.

[aaronpriest]

Wow, looks like I can download 10 meter for all of Maine under the 4GB limit. Thanks for sharing this site!

I wonder if the 12-digit watershed is as good or better than the USGS NHD database?

[aaronpriest]

Well, this was disappointing. I downloaded the 12-digit (haven't tried 8-digit yet) watershed dataset as one shapefile unfortunately and found that practically unusable for GPSMapEdit, and I can't re-request the same data in multiple shapefiles for another 5 days. The geographic names were severely lacking compared to data from GNIS. And 10-meter NED was only available in GeoTiff format, but I'd like to try ArcGrid with Global Mapper instead of individually processing each .tif with Dem2Topo.

So much for hoping to find one easy batch download of states/counties. The TerraServer ortho imagery from this site looks promising though.

[John_M]

The 12-digit watershed has polygons of the land of the watershed. For gps maps we need the surface water features such as lakes and ponds. The USGS NHD database has that. I will e-mail you

[aaronpriest]

Yup, I pretty quickly figured that the 12-digit watershed wasn't what I needed, though I wasn't quite sure what it was until your explanation. Thanks. I've already got all the 8-digit subbasins for Maine from NHD. I actually found it to be easier and less tedious than all the NEDs I'm still waiting on. I was kinda hoping to find everything on one convenient site, but oh well. Hehe!

[John_M]

I have the NED 30 data for Maine. I will get the NED 10 data make 20  contours foot from the two data sets and see the  NED 10  contours are better.  I am using gdal_contour to make contours so the  GeoTiff format good.

[Perry]

Well, this was disappointing. ...And 10-meter NED was only available in GeoTiff format, but I'd like to try ArcGrid with Global Mapper instead of individually processing each .tif with Dem2Topo.

Why not just use Global Mapper to process the GeoTiffs?

[aaronpriest]

Honestly, I haven't really figured out how to use Global Mapper yet. I've done GeoTiffs with Dem2Topo quite a bit, but my first real experience with Global Mapper was trying to follow the tutorials. I'm waiting to read the remaining unwritten articles to understand what to do with the files that Global Mapper created. I couldn't find a way to export as shapefiles or anything that I'm already familiar with, it was all grayed out. There's a step I'm missing and don't quite understand yet I guess.

At the moment, I've got the whole state of Maine (10-meter I believe) in ArcGrid format and I've got Penobscot County in GeoTiff. I'll probably finish my county the way I'm already familiar with using Dem2Topo, OpenStreetMap, etc. I'd like to see how Oz is doing some of the other cool stuff though like railroad tracks, power lines, etc. This should be a pretty sweet site when all the tutorials get finished.

[-Oz-]

Yea, sorry military took me away.  The next segments are coming.  I also created a program that will do the contours pretty quickly for those that don't have Global Mapper and its a little faster and works better with large areas than Dem2Topo.

[Perry]

I was wondering: using Global Mapper is there any advantage to downloading elevation in ArcGrid format rather than GeoTiff?

[-Oz-]

not really either will definitely work.  Originally the 4 smaller segments were a little faster to download with multiple computers than the one single.