Help With USGS

[overlordchuck]

Perhaps I'm just a dummkopf or a super-newbie (oh wait...I know that already), but I'd really appreciate it if anyone could explain to me how I'm supposed to use NEDs off of http://seamless.usgs.gov/

Seriously, any help would earn you my undying gratitude.

[rcallicotte]

Not sure, specifically, but did you do a search on Planetside?

[SeerBlue]

The USGS site is not the easiest interface to use. Basically you need to zoom into the approximate area you want, then go to the right side of the panel and click Download, and then select the elevation> tab to chose the type of file you want, (srtm finished 1 arc sec is the best for USA,srtm finished 3 arc sec for the rest), then go over to the left side of the panel and select "define rectangular download area" and click and drag the exact area you want. The box will turn green and a download window will open to tell you your status. then save your file.
You will then need to convert your file to a .ter, 3dem is easy and free
www.visualizationsoftware.com/3dem.html .
  I will attach a screen cap of the   usgs site below, if you need any 3dem help just ask...It has been awhile since I used it as I use Global Mapper
SeerBlue

[chefc]

The USGS site is not the easiest interface to use. Basically you need to zoom into the approximate area you want, then go to the right side of the panel and click Download, and then select the elevation> tab to chose the type of file you want, (srtm finished 1 arc sec is the best for USA,srtm finished 3 arc sec for the rest), then go over to the left side of the panel and select "define rectangular download area" and click and drag the exact area you want. The box will turn green and a download window will open to tell you your status. then save your file.
You will then need to convert your file to a .ter, 3dem is easy and free
www.visualizationsoftware.com/3dem.html .
  I will attach a screen cap of the   usgs site below, if you need any 3dem help just ask...It has been awhile since I used it as I use Global Mapper
SeerBlue

Excellent resource and really not that difficult to utilize

[overlordchuck]

Thanks very much!  Now, one more question from the super-n00b...how am I supposed to open it with 3DEM?  I unzipped the file it saved and opened 3DEM, and now I can't open any file within the folder.

[bigben]

I've uninstalled 3DEM because I finally upgraded my GlobalMapper to the new version so I can't tell you for sure whether it will open NEDs. When you unzip your USGS download you will get a folder with a subfolder of the same name. Inside that subfolder you will find a file called "w001001.adf" which is the file containing the elevation data (it'll be the biggest file).

The best data you can get for most of the US is 1/3" NED (around 10m). 1/9" is available for a few small regions.  To see the coverage, select the desired elevation set in the DISPLAY section.  I'm not sure of the differences between 1" NED and 1" finished SRTM3, but I do know that the 3" SRTM3 is not adjusted to show a "naked" terrain. There are visible bumps equivalent to rows of trees etc...

I see they've gone for a brownish colour scheme this year...

It's been ages since I downloaded from Geocommunity, they had DEM files for download which you can open in 3DEM. Only problems were that you need to download a lot of tiles, and you now have to pay to download 10m data.

Canada is probably the next best for free data <http://geobase.ca/> although the coverage of 10m data is on a state by state basis. At least they have DEMs for download which shouldn't be a problem for you.

Which area are you looking at?

[overlordchuck]

Mostly around the west in Colorado and such, just trying to find nice terrains.  I was just hoping there was a way to convert the .adf to a .ter file.

[bigben]

My downloading of 10m data hasn't quite made it that far east yet, but I'm only a degree or two off.  Searched for a couple of ADF - Geotiff/DEM converters but haven't found anything that works with the tile I have (although they may be a bit big?)

• TotalGIS Converter
  Created a 1024x1024 white tiff (NOT geotiff)
• fGIS
  I could get the data imported, and could see it in the layer properties but couldn't get it to display or export... but I didn't try for very long

GlobalMapper does it quite nicely but I'm assuming your using 3DEM because of its price (or lack there of) I still have a request to complete for the TerragenTerrain Yaho group, but after that, if you can convince me that the area is interesting enough (usually not that hard to do) I don't mind making a terrain set of it.

[rcallicotte]

Chuck,

This is a good place for getting the download in TER - http://geoengine.nima.mil/geospatial/SW_TOOLS/NIMAMUSE/webinter/rast_roam.html

Go here - http://www.terrainmap.com/ and then look under the Directory for the Sinai Challenge to get semi-helpful instructions on how to get your data and then save it as a TER file or a DEM or a TIF, depending on what's available for that.  I highlighted a couple of things that I discovered are important.  I downloaded both "Center Point Download" and "Area Download".  I found I needed to go into Terragen .9 to resize the TER to 4096X4096.

[JimB]

Thanks very much!  Now, one more question from the super-n00b...how am I supposed to open it with 3DEM?  I unzipped the file it saved and opened 3DEM, and now I can't open any file within the folder.

Chuck, it's really simple but not obvious. After you've selected the area to download the Request Summary Page pops up. Click on 'Modify Data Request' and scroll way down until you get to the ticked (NED) field, with the drop down options to the right. Change the 'ArcGRID' option to 'GeoTIFF'. Then go to the bottom and click 'Save changes and return to summary'. The rest is obvious, and 3DEM should be able to use the TIFF.

[bigben]

Well there's your answer...   

Another thing I find handy with the USGS site is to bookmark a request summary for each data type that I donwload. Towards the end of the URL you will find 4 numbers separated by commas that are the coordinates of the NS/EW bounds of the area. I find it easier just editing this url to submit another request when I know exactly what I want.

[overlordchuck]

Oh hey, thanks a lot JimB, and really, all you guys.  I shall definitely try this whenever I get home!