[Freegis-list] .3cd and .3tx files info needed

emo.da@jumpy.it emo.da at jumpy.it
Fri Oct 7 16:58:15 CEST 2005

Hello to everybody,
I'm an Italian Civil Engineering student and I'm doing a bachelor thesis
about airport noise.
To do so, I'm using INM software
( http://www.faa.gov/about/office_org/headquarters_offices/aep/models/inm_model/
I need digital elevation files for this model, the only problem is that it
accepts ONLY .3cd (binary format by Micropath Corporation http://www.micropath.com/
) and .3tx (text format by Micropath Corporation) files, and I can't find
support for them. I have an elevation .grd file (Golden Software Surfer)
but I can't find a way to translate/convert it in a .3tx file containing
terrain elevations covering a one-by-one degree area; below there's a description
of the .3tx format.

The .3tx text format:

Lat Long

-Lat    is the latitude of SW corner (integer degrees)
-Long  is the longitude of SW corner (integer degrees)
-elevation is terrain elevation MSL (integer meters)

The first line in the file defines the southwest cornerof the one-by-one
degree area.
North latitude and east longitude are positive integers; south latitude and
west longitude are negative integers. The SW corner must be on integer degrees.
There must be exactly 1201*1201=1442401 lines following the first line. Each
line contains one number - the elevation, in integer meters, of the terrain
above mean sea level. The elevation of the SW corner is the first integer,
the elevation that is 3 arc-seconds to the north is the next integer, and
so on until the top edge (integer degree latitude) is reached.
Then move 3 arc-seconds to the east, start at the bottom edge, put in another
1201 elevations while moving north, and so on until the file is finished.

So, if anyone of you can help me telling me about a program, a tool or a
software that can manage my Surfer .grd file and convert it into a .3tx or
a .3cd one, I'll be very thankful!

By the way,
thank you a lot in advance

Davide Borelli

( emo.da at jumpy.it )

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