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[GEMPAK #QYA-206571]: Embarassing Simple GINI format question, how to convert 8bit raster to actual data

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  • Subject: [GEMPAK #QYA-206571]: Embarassing Simple GINI format question, how to convert 8bit raster to actual data
  • Date: Fri, 21 Nov 2014 12:06:42 -0700
Hi Daryl,

For the Unidata FNEXRAD GINI images there is a calibration block in the unused 
portion of the GINI header that is used for the image calibration values.

In gempak/source/gemlib/im/imgi2gm.f:

C*      Get calibration Block if it exists.
C*      Currently, only Unidata calibrations exist, using
C*          Word 47 = 128
C*      to signal that a calibration block is present.

followed by CALL IM_CALBAR_INIT and then building of the calibration values 
from the header on line 311.

These calibration ranges are defined in $GEMTBL/unidata/nex2gini.tbl

For non-Unidata GINI images, I'm looking in the ICD at 
http://www.nws.noaa.gov/noaaport/document/ICD%20CH5-2005-1.pdf

Page 24 mentions the nav/cal block:

7. Octet 47, Navigation/Calibration Indicator 
 Set to 0 to indicate no nav./cal. information included 
 (PDB = 512 octets, octets 48-512 are blanks) 
 Set to 1 to indicate nav. and cal. information included 
 Set to 2 to indicate nav. information only included 
 Set to 3 to indicate cal. information only included 
 (For values 1-3, PDB size will likely increase 
to no more than 2048 octets). Additional ICD tables 
will be generated defining nav./cal. octets for each of 
the creating entities (satellite/imagery types) for 
which nav./cal. is to be included. 


Is this what you're looking for?

-Michael


> Hi Unidata,
> 
> Please hit me with the clue-by-four, but I can't seem to resolve how to
> properly convert the 8bit value stored in GINI format products to an
> actual data value.  Is there some GEMPAK table that describes this or
> something in the GINI header that describes it?
> 
> thanks
> daryl
> 
> --
> /**
> * Daryl Herzmann
> * Assistant Scientist -- Iowa Environmental Mesonet
> * http://mesonet.agron.iastate.edu
> */
> 
> 

Ticket Details
===================
Ticket ID: QYA-206571
Department: Support GEMPAK
Priority: Normal
Status: Open