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20050817: McIDAS - ANM GRIB file decoding with gribdec

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  • Subject: 20050817: McIDAS - ANM GRIB file decoding with gribdec
  • Date: Wed, 17 Aug 2005 09:56:18 -0600
>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