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[McIDAS #EOG-391161]: pygvar update



Hi Ioan,

re:
> I have told you in the past I will update you about  pygvar
> 
> I have run recently into some issues with GOES15 images. Concretely,
> GOES15 images  from CLASS are shifted systematically on both axes (X
> and Y) when I reproject them using pygvar
> 
> So i started to look into it and for start compared the navigation code
> and block from the GVAR with the navigation block and code from the same
> image from NASA cyclone server
> 
> ftp://cyclone.msfc.nasa.gov/
> 
> The cyclone image was navigated correctly and the reason was it had
> different start  image line and element values  in the directory (words
> 6 and 7).
> 
> In pygvar navigation I use INFLN anf IWFPX words from Block0 for the
> same purpose.
> 
> So Conclusion 1: the software that produced the AREA files on the NASA
> server (probably McIDAS X) somehow fixed these issues by altering these
> two words. I have no clue how.
> 
> Next i generated myself an AREA file from the same gvar using mcidasx
> and realized its start image lines and element are identical to mine
> from block 0, yet,... the image was again navigated correctly.
> 
> I generated a navigation block from gvar block0, compared with the
> navigation block from the second area file and realized I am missing
> something.....specifically the instrument nadir cycles (north south)
> and cycles increment(north south) ....were incorrect.
> 
> I concluded that probably, some changes in the GVAR stream happened with
> GOES14 onward.
> 
> I believe there are 3 version of the GVAR stream. Are you aware of any
> doc that describes the differences:)))
> 
> Best
> Ioan
> 
> From address@hidden  Wed Jan 31 06:08:58 2018
> 
> I am bothering you again.
> 
> I've got this idea to search for the nadir data in the header, so
> i scanned Block0 byte by byte and found out the correct values were
> located at words 3832-3836 And voila....goes15 works correctly. it took
> me 2 1/2 days to fix this
> 
> all the best

To answer the question you posed in your first email, no, I don't know of
any documentation that describes the differences that you mentioned.

Since you seem to have solved your problem, I am assuming that I can
view your emails as a heads-up to let me know.

Please let me know if you are expecting something more from me on this
topic!


Cheers,

Tom
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Ticket Details
===================
Ticket ID: EOG-391161
Department: Support McIDAS
Priority: Normal
Status: Closed
===================
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