HowTo Mosaic ASTER Global Digital Elevation Model (GDEM)

A second version of ASTER GDEM was released in Oct. 17 2011 by The Ministry of Economy, Trade and Industry of Japan (METI) and the National Aeronautics and Space Administration (NASA). The GDEM is in a 30m pixel resolution and 1x1 degree tiles. The data is distributed as zipped GeoTIFF files. When a larger than 1x1 deg. DEM is needed for Interferometry processing, you can use my GDEM.py script available from my script page. This python script will need a system with pylab and PIL python modules.

Simply:

Download the GDEM zipped files (see here on how to do that).

Unzip the zip files in the working directory.

The working directory should contain sub-directories containing the GeoTIFF files.

Run the script giving -h for help or the final DEM name as arguments.

The Final DEM is aimed for using as DEM in ROI-PAC interferometry processing.

If a -g is added as an argument, the produced DEM will be suitable for interferometric processing using Gamma software.

Orbits and other auxiliary data

I use Delft orbital data (ODR) which is available from here. don't forget to use the precise version and to download all .ODR files (make sure it is not .odr after downloading) and the arclist. also, download and install getorb software and link or move the executables to the ROI_PAC binaries directory.

I also use DORIS orbital data for Envisat which is available from here. but will require a user and password. the DORIS data is used when no ODR data is yet to be available for new Envisat images.

for Envisat I also use auxiliary data available from here.

in my lab, all the orbital data is in ~/ROI_PAC_3_0/Delft with directory tree as follows:

in ~/ROI_PAC_3_0/Delft I put the Envisat auxiliary data (INS and XCA files)

• doris/Envisat/YYYYMM contains orbital data for the year (YYYY) and month (MM)
• Envisat contains Envisat Delft orbit data (.ODR .res arclist files)
• ERS1 contains ERS1 Delft orbit data (.ODR .res arclist files)
• ERS2 contains ERS2 Delft orbit data (.ODR .res arclist files)

the files must be updated from time to time as more images are added to the list.