DEM problem

[rwk]

I want to download DEM of lower Hunterdon County, NJ, but the part where the rail line is black, with no DEM, it's like part of the DEM is missing. I got it from the National Map Viewer. I want the rail line from Flemington, NJ to Lambertville, NJ through Ringoes, NJ which is the Black River & Western Railroad. Is there another source for US DEM NED GeoTiff data compatible with TranzsDEM besides National Map Viewer? It seems like part of Hunterdon County, NJ is missing on the National Map DEM What do I do?

 

[jhuravitch]

I don't know if this has anything to do with your problem, but the National Map Viewer was down during April 12 for a while. Could have caused a problem with the download maybe but I highly doubt it. For DEMs I have yet to find another decent site for elevation data other than the USGS site. I too would like to know if anyone knows of other decent sites for DEMs.

 

[SharkNose]

rwk,

Hunterdon county is only partially covered by 1/9 arc second DEM data, as you found out. 1/3 arc second data is available for the entire county. Choose 1/3 arc second in ArcGrid format. The latest version of TransDEM can read this format. Then you can merge the 1/3 arc second data with the 1/9 arc second data in TransDEM. TransDEM will honor the higher resolution data when doing this.

Warning: 1/3 arc second in ArcGrid format from the National Map Viewer results in very large files! Approximately 400 MB! You're likely to get half of New Jersey with one download!

Andrew

 

[rwk]

Well, looks like I have to pay for another upgrade to TransDEM. I sent an email to Roland to upgrade. The version I have now, 2.2.0.1 won't read ArcGRID DEM's. You need the latest version which you can only get by paying. Now I just have to wait for a reply, pay by PayPal, then receive the upgrade version to be able to open the ArcGRID files.

 

[steamboateng]

The National Map Viewer now downloads packaged 1/3 arc sec data in discrete 1degx1deg bundles. The nice thing is that you can get 3 or 4 different routes from a single download!