Re: [cf-satellite] Ang.: Making a proposal for the addition of the geos projection

• To: <cf-metadata@xxxxxxxxxxxx>, <cf-satellite@xxxxxxxxxxxxxxxx>
• Subject: Re: [cf-satellite] Ang.: Making a proposal for the addition of the geos projection
• From: "Randy Horne" <rhorne@xxxxxxxxxxxxxxxxx>
• Date: Mon, 28 Nov 2011 18:24:07 -0500

Martin:

Discussion with our Image Navigation and Registration lead (Dr. Jim Carr) 
reveals that the EUMETSAT GEOS projection is not the same as the GOES-R 
projection (i.e. the ABI fixed grid).

The reason has to do with the gimbaling characteristics of the two imagers.  
Both of the imagers are dual gimballed.   In the case of the GEOS imager, the 
inner gimbal axis is in the N/S axis (i.e. the x-axis) and the outer gimbal 
axis is in the E/W axis (i.e. the y-axis).  In the case of the GOES-R imager, 
this is reversed.

The implication is that the order of applying the x and y rotation matrices is 
reversed when data points are projected, and geodetic lat/lon coordinates 
calculated.  As a result, the location of the data points on the Earth are 
different between GEOS and GOES-R for specific radian values associated with 
the same N/S and E/W scan angles.

As a result, the order in which the rotation matrices are applied must also be 
captured.

Feel free to contact me for additional details.

very respectfully,

randy


Re: [cf-satellite] Ang.: Making a proposal for the addition of the geos 
projection
To: <cf-satellite@xxxxxxxxxxxxxxxx> 
Subject: Re: [cf-satellite] Ang.: Making a proposal for the addition of the 
geos projection 
From: Martin Raspaud <martin.raspaud@xxxxxxx> 
Date: Thu, 24 Nov 2011 09:08:12 +0100 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 23/11/11 21:03, Tom Rink wrote:
> Hi Martin,

Hi Tom,

[...]
>>     short x(x);
>>       :standard_name = "projection_x_coordinate";
>>       :add_offset = 1856
>>       :scale_factor = -208.16554260253906
>>       :units = "rad"
[...]

> This is a neat idea, that way different conventions for north-to-south
> (GOES)
> south-to-north (SEVIRI) could be handled, ie. if I'm understanding your
> suggestion?

Yes exactly. Putting negative scaling factors allows to reverse the
scanning direction so to say :)

Best regards,
Martin
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.14 (GNU/Linux)
Comment: Using GnuPG with Red Hat - http://enigmail.mozdev.org/

iQEcBAEBAgAGBQJOzftsAAoJEBdvyODiyJI48DkIAJGcE8ueuOK1GdozxokVxSer
apYXksYgQKWwiHXInoa1EMhUoOt5Y/Hys/JIHs0EVHlDCiM9ovdD4Llg9FMpfjJu
VmY+Z5DQqnMOGb/1TqRFDUgbA563r8zTRzdiEFB0pWUNjVvfN/xaW+i1BQgmx8ey
+czkyufWx24nIw+DQDECjkRjQDN6brvHmhiSKhbftIq/fBB6BrjFekhQNAulZGgo
rS8c2q0dtWuGzjYFsz922t08dH13FbH3bG9x0TUfz6X97byVBRYuFHekHLEX1kkO
hgfjVQMid6j+ChS3z0U6M9E9/vIT9xoVCHiYIctL7PKKE+bFT43QGDjvjkhfwc8=
=bvUc
-----END PGP SIGNATURE-----

begin:vcard
fn:Martin Raspaud
n:Raspaud;Martin
org:SMHI
adr;quoted-printable;quoted-printable:;;Folkborgsv=C3=A4gen 
1;Norrk=C3=B6ping;;60176;Sweden
email;internet:martin.raspaud@xxxxxxx
tel;work:+46 (0)11 495 8261
tel;cell:+46 (0)11 495 8261
url:www.smhi.se
version:2.1
end:vcard


 

 
..............End of Message ...............................-->