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20050817: McIDAS - ANM GRIB file decoding with gribdec



>From: "Oana" <address@hidden>
>Organization: National Administration of Meteorology
>Keywords: 200508090846.j798kTjo016776 McIDAS-XCD gribdec

Hi Oana,

re: problem in gribdec code found and fixed
>I am waiting for this gribdec version.

OK.  Here is the access information:

<as 'mcidas'>
cd ~mcidas
mkdir gribdec
cd gribdec

ftp ftp.unidata.ucar.edu
  <user> ...
  <pass> ...
  cd unix/gribdec
  binary
  get gribdec.tar.gz
  quit

gzcat gribdec.tar.gz | tar xvf -
make

Successful building of the gribdec bundle assumes that McIDAS has
been installed in the same account on the same machine in /home/mcidas.

Before your run gribdec, I suggest modifying your MCPATH to include
the /home/mcidas/gribdec directory as the first MCPATH directory:

export MCPATH=/home/mcidas/gribdec:$MCPATH

You will need to read through the comment section at the beginning
of gribdec.pgm to see how to run the decoder.

I am registered as Oana Unidata user.

OK.  I will work on getting you added to the exception list for McIDAS
downloads.

re: PDF version of training workshop and Users Guide due out soon
>Ok.

>Now, I have a new question for you:
>
>-          I am trying to make a NDVI (Normalized Difference Vegetation 
>Index) from MSG channels 1 and 2. The problem is that after I make the 
>difference between the two channels I cannot display the negative values. If 
>I understood correctly, McIDAS displays all these values between 0 and 255. 

Yes, you understood correctly.

>But, I need them to be between -1 and 1 (for NDVI) because of the land-water 
>boundaries recognition. How can I do that?

Everything must be scaled so that values fall between 0 and 255.  So, values
between -1 and 1 need to be mapped to some range between 0 and 255.

>Thank you very much for your help,

No worries.

>Oana Nicola
>National Administration of Meteorology
>Address: Sos. Bucuresti-Ploiesti nr.97=20
>013686 Bucharest, ROMANIA
>Phone: +40 21 230.31.16=20
>Fax: +40 21 230.31.43=20
>E-mail: address@hidden

Cheers,

Tom
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>From address@hidden  Thu Aug 18 00:27:24 2005

>Helo Tom,

re: gribdec access information

>It just works perfect.

re: need to scale image values to fall between 0 and 255

>Ok. I'll do that.

>McIDAS download was successful.
>Thank you very much,

>Oana

NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.