[2012 Feb 07] Xntg v1.3
[2011 Mar 02] Intg v3.12
CONUS, Alaska, Hawaii, Guam and
Northern Mariana Islands, American Samoa,
Puerto Rico and U.S. Virgin Islands
files are available
For working with the GEOID09 model, two computer programs are provided
as compiled executables for both PC Win32 (INTG.EXE and XNTG.EXE)
and Sun Unix (INTG and XNTG) platforms, along with the source code.
INTG interpolates geoid heights from data files using
user-provided coordinates. XNTG extracts sub-grids from the binary
data files, converts back and forth between binary and ASCII data formats,
and gives statistics about a data file.
To determine geoid heights with the GEOID09 model,
download an INTG executable and at least one data file.
You need only to select those data files that cover your region of interest,
and the program will recognize which files are present. Select one or more of
the data files either by using the graphical or data interfaces.
The binary formats of all data files follow the IEEE Std. 754 binary format
(big-endian) as they are developed in a Unix environment.
Programs INTG, XNTG, INTD and XNTD are all designed to
determine the user's platform and will automatically byte swap the data.
Users desiring a little-endian binary format (common to a Windows platform)
should process the desired files through XNTG (on a Windows platform)
and select option 2. The user should select the default spatial
extents for the output file. Give the output file a unique
name and then change it to the original input file name after the XNTG
program is complete. The resulting file will cover the same
range as the original file but will be byte-swapped.
Repeat as necessary for the desired number of files.
A GEOID09 geoid height can be computed for a specific geographic
location or for a file of input points.
Position coordinates should be in the appropriate NAD 83 reference frame.
PC Windows (little endian) data files
Unix, SGI (big endian, network order) data files