TGZ file?

JSL

I'm trying to download a global 1-km DEM from a NOAA site and having a problem extracting it--what would be the best way to bring the data from this site into GM:

https://ngdc.noaa.gov/mgg/topo/gltiles.html

CarrickCon

Hi JSL,

You need to use GUNZIp as explained in Section 11.G of The Globe Project Report entitled "11.G.ii. GUNZIP the Compressed Data from the Web Site" here: https://ngdc.noaa.gov/mgg/topo/report/globedocumentationmanual.pdf

Happy hunting,

/al

CarrickCon

Should have said its on page 89 of the document (or page 97/147 of the pdf)

Ta,

/al

JSL

Thank you very much--unfortunately, that's way above my computer skills pay grade to figure out. I'll ask my computer engineer son to see if he can help 😉

CarrickCon

Hi JSL,

I agree that its cumbersome and surprising that NOAA don't have a more direct way of accessing the data.

Are you aware that you can access ASTER Global DEM data via Global Mapper directly? Just need to click on "globe" icon to "Connect to Online Data" as per attached screen grab.

There are also many, much easier to use sources of DEM data available on line.

Cheers,

/al

JSL

Thanks, I didn't realize ASTER was worldwide--I thought it was just the middle latitudes, like SRTM. That makes my life a lot easier!

CarrickCon

Yep, not only is it Global, it is also 1 arc-second (~100 m) grid data, while the NOAA data that you were looking at is 30 arc-second (~1 km) grid data, so the resolution is much better.

Ta,

/al

CarrickCon

P.S. Just to be clear, SRTM coverage is global also, not just "middle latitudes"...

JSL

What I meant is that SRTM only covers between 60 degrees N-S:

I've used ETOPO or GMTED before to fill in the northern and southern areas, but now I'll check how ASTER meshes with SRTM.