Important changes regarding DEM formats on the US National Map Server.

J

JCitron

Trainzing since 12-2003
For those of us that have TransDEM, this is important. TransDem won't handle the ArcGrid format. It requires GEO Tiff only from the national servers, so if anyone needs maps, I think the time to download them is NOW

http://nationalmap.gov/elevation.html#downloads

[SIZE=+0][SIZE=+0]
Note: The National Map is moving to provide prepackaged, staged products for faster and more efficient downloads. Beginning December 18, 2012, NED 1- and 1/3-arc-second data will be available through prepackaged, downloadable, 1- degree tiles in ArcGrid and GridFloat formats only. Users can still define custom areas of interest. However, all tiles intersecting the area of interest will be included in the delivery. In addition, beginning with the February release of the NED, it is anticipated that all elevation products (1, 1/3 and 1/9 arc-second) will be available as prepackaged, downloadable files in .img format, a robust format easily read by nearly all GIS software. All other format options will no longer be available after the move to staged products is completed. If you have questions or concerns about these changes, please contact us at tnm_help@usgs.gov.

[/SIZE][/SIZE]
 
I'm assuming this won't affect the NASA pre-packaged SRTM data which I prefer to use, even for US projects?
 
JCitron said:
For those of us that have TransDEM, this is important.
Click to expand...
Thanks a lot for posting this.

Well, until today I've had other plans for the holiday season. :(

TransDEM 2.3.1 with NEDF Australia support will still come out first before I tackle the new NED (US) challenges. What's wrong with GeoTIFF?


@Vern:
You are not using SRTM for the US, are you? Even at 1 arc sec, terrestrial NED is far better then orbital SRTM, no forests, no buildings disturbing surface level. And you would use 1/3 arc sec anyway.
 
Last edited:
geophil said:
Thanks a lot for posting this.

Well, until today I've had other plans for the holiday season. :(

TransDEM 2.3.1 with NEDF Australia support will still come out first before I tackle the new NED (US) challenges. What's wrong with GeoTIFF?


@Vern:
You are not using SRTM for the US, are you? Even at 1 arc sec, terrestrial NED is far better then orbital SRTM, no forests, no buildings disturbing surface level. And you would use 1/3 arc sec anyway.
Click to expand...

Roland,

Enjoy your holiday. Come out with the patch when you return to work. :)

I wonder too what is wrong with GeoTiff.

I came across this while looking for something. It's a good thing I saw the link at the top of the page.

John
 
Thanks for the heads-up! I've been working in Google Earth to create paths for all rail lines in the USA, starting with the east coast. Eventually, I will be wanting to select portions of the map to export/import to TransDem where I will need to merge the routes with DEM data. I have been using GeoTiff for a long time, and am not happy with any changes, however, since Roland has been very supportive of TransDem, I don't think I have anything to worry about. For now, perhaps I will download some of the old GeoTiff map sets to work with until the TransDem patch is released.
Of course, I don't expect to ever finish my complete rail map of the USA. Just working on NY now, and it's a lot of work. But it has been fun work for me; relaxing most of the time, although it does get tedious when I cannot find the old (abandoned) lines, or the GE images aren't good enough to create accurate track maps.

Frank - the only constant in life is change!
 
JCitron said:
For those of us that have TransDEM, this is important. TransDem won't handle the ArcGrid format. It requires GEO Tiff only from the national servers, so if anyone needs maps, I think the time to download them is NOW

http://nationalmap.gov/elevation.html#downloads

[SIZE=+0][SIZE=+0]
Note: The National Map is moving to provide prepackaged, staged products for faster and more efficient downloads. Beginning December 18, 2012, NED 1- and 1/3-arc-second data will be available through prepackaged, downloadable, 1- degree tiles in ArcGrid and GridFloat formats only. Users can still define custom areas of interest. However, all tiles intersecting the area of interest will be included in the delivery. In addition, beginning with the February release of the NED, it is anticipated that all elevation products (1, 1/3 and 1/9 arc-second) will be available as prepackaged, downloadable files in .img format, a robust format easily read by nearly all GIS software. All other format options will no longer be available after the move to staged products is completed. If you have questions or concerns about these changes, please contact us at tnm_help@usgs.gov.

[/SIZE][/SIZE]
Click to expand...

Hello John,

Thank you for this very important information.

I'm just wondering - Will this have an effect on all regions ( Africa, Australia, Eurasia, North-America, South-America )?

Best regards

Kurt :wave:
 
belgian46 said:
Hello John,

Thank you for this very important information.

I'm just wondering - Will this have an effect on all regions ( Africa, Australia, Eurasia, North-America, South-America )?

Best regards

Kurt :wave:
Click to expand...

Hi Kurt,

This only affects North America since this is the USGS National Map database that's being updated. Who knows though what the future will bring. I don't understand why they're changing the format unless it has to do with making everything "easy", essentially dumbing down the services.

You're welcome.

John
 
JCitron said:
Hi Kurt,

This only affects North America since this is the USGS National Map database that's being updated. Who knows though what the future will bring. I don't understand why they're changing the format unless it has to do with making everything "easy", essentially dumbing down the services.

You're welcome.

John
Click to expand...

JCitron said:
Hi Kurt,

This only affects North America since this is the USGS National Map database that's being updated. Who knows though what the future will bring. I don't understand why they're changing the format unless it has to do with making everything "easy", essentially dumbing down the services.

You're welcome.

John
Click to expand...

Hello John,

I used this link http://dds.cr.usgs.gov/srtm/version1/Eurasia/ to get the hgt-files for Belgium. When you click on parent directory you will return until http://dds.cr.usgs.gov is reached.

Best regards

Kurt :wave:
 
Just a quick update:

I have tested my implementation of ESRI Binary Grid with a National Map NED download in "Arc Grid" format and it appears to work. So, after the announced retirement of GeoTIFF (still available at the moment), "Arc Grid" will be the choice for TransDEM users for the next few weeks, until they retire that as well. For TransDEM this is a new format which I have added for the Australian NEDF data source. ESRI Binary Grid aka Arc Grid will come with TransDEM 2.3.1 and I am still hoping to finish it before Christmas.
 
Roland,

Thank you very much for your work on this.

There is no need to rush the release before Christmas. Take your time and enjoy the holiday. :)

John
 
GeoTIFF is gone now.

Fortunately, I finished TransDEM 2.3.1 today, see here. It brings ESRI Binary Grid aka Arc Grid, our new option for National Map NED.

Be aware, downloads are huge for 1/3 arc sec (I haven't tried 1/9 arc sec), nearly 400 MB for a pre-packaged 1 x 1 degree file. I guess they will receive a few complaints about that, demanding smaller servings.
 
Last edited:
Roland,

Vielen Dank!

And you're right, I just downloaded the Camden quad from New Jersey and ended up getting most of the state of Delaware with it.

Thanks for your efforts and enjoy your holidays!

Andrew
 
Roland,

Thank you very much for updating TransDEM for us. This is greatly appreciated by the Trainz community.

Best regards and have a Merry Christmas.

John
 
Last December USGS made the announcement about abandoning seamless services for DEMs and retiring data formats. They also said that the next change will be in April:

http://nationalmap.gov/data_delivery/ned.html
In addition, beginning with the April 2013 release of the NED, it is anticipated that all elevation products (1-, 1/3- and 1/9-arc-second DEMs) will be available as pre-packaged, downloadable files in '.img' format, a robust format easily read by nearly all GIS software.
Click to expand...
I don't know about "nearly all GIS software" but unfortunately TransDEM wasn't among those.

After some research it appeared that ".img" could mean ERDAS Imagine, another of these formats from the early 90s, when GIS was born.

Meanwhile, USGS has updated that announcement and offers some sample data for download on that page. That helped me a lot. I have now implemented support for ERDAS Imagine as a prototype and it seems to work. The big difference to ESRI Binary Grid, the format we are currently using: Img is much faster to read. Opening ESRI Binary Grid involves a lot of jumping hence and forth when accessing tiles and blocks and that it slow. ERDAS Imagine has a more efficient file structure and it also packs everything into a single file, like GeoTIFF.

However, I do not yet know the encoding for void points in this format. ESRI Binary Grid as used by USGS brought some surprise here in January. So I will wait until more data becomes available for further testing before publishing the TransDEM update.

Both ESRI Binary Grid and ERDAS Imagine are rather complex formats and documentation leaves a lot to desire. Fortunately there is a library, called GDAL (X11/MIT license) which most people seem to use (including the USGS) and TransDEM does the same.

(I will also post this in the TransDEM thread.)
 
You must log in or register to reply here.

Similar threads

G
Why to avoid Lat/Long-Reader with TransDM routes
Replies
9
Views
6K
RPearson
R
Back
Top