20020723: SSEC, CSU 4 km visible calibration (cont.)

>From: Darren Gallant <address@hidden>
>Organization: UCAR/JOSS
>Keywords: 200207111918.g6BJIGa29261 McIDAS AREA calibation

Darren,

>I'm trying to subsect an image, but imglist reveals something peculiar
>about this image's ecor and lcor values:
>
>Pos Satellite/         Date       Time      Center      Res (km)
>Image_Size
>     sensor                                 Lat  Lon    Lat   Lon
> --- -------------  ------------  --------  ---- ----  ----- -----
>------------
>9966  G-8 IMG        1 AUG 00214  20:15:00    31   86
>    Band: 4  10.7 um Surface temp; longwave window      5.18  2.42  3245 x
>8472
>     proj:    0 created: 2002199 181713  memo: RT GVAR
>     type:GVAR     cal type:RAW
>     offsets:  data=    3328 navigation=  256 calibration= 2816 auxillary=
>0
>     doc length: 228   cal length:   0   lev length:   0 PREFIX= 232
>     valcod:  214201500 zcor:  0 avg-smp: N
>     start yyddd: 2000214  start time:201515  start scan:  401
>     lcor:-1639  ecor: -3363  bytes per pixel: 2  ss: 70
>     Resolution Factors (base=1):   Line=    4.0   Element=    4.0
>imglist.k: done
>
>I thought lcor and ecor were always positive. Are there positive
>equivalents?

No.  The image in an AREA file can be offset so that the upper left
point of the AREA refer to an image LIN,ELE that doesn exist.  Think
of taking an original image and then translating the values down and to
the right in the AREA.  The upper left portion of the image now refers
to a LIN,ELE that is not in the new image:

                   Original
Image  (1,1)
          +------------------------+
          |                        |
          |         ......         |
          |        ........        |
          |       ..........       |
          |      ............      |
          |     ..............     |
          |     ..............     |
          |      ............      |
          |       ..........       |
          |        ........        |
          |         ......         |
          |                        |
          |                        |
          +------------------------+


         Translated  down and to left

Image (-5,-5)
          +------------------------+
          |                        |
          |                        |
          |                        |
          |                        |
          |    +                   |
          |                        |
          |              ......    |
          |             ........   |
          |            ..........  |
          |           ............ |
          |          ..............|
          |          ..............|
          |           ............ |
          +------------------------+


Tom

>From address@hidden Wed Jul 24 12:28:57 2002
>Subject: Re: 20020723: SSEC, CSU 4 km visible calibration (cont.) 

Thanks,

Your explanation makes sense. So if I wanted to copy the image, I would
use "LINELE=1 1 I PLACE=ULEFT" in my IMGCOPY?

Darren

>From address@hidden Wed Jul 24 12:35:21 2002
>Subject: Re: 20020723: SSEC, CSU 4 km visible calibration (cont.) 

Unidata Support,

Actually using "LATLON=31 86 PLACE=CENTER" works much better.

Thanks

Darren

Darren R. Gallant               UCAR/JOSS
Programmer/Technician           Joint OfFice Of Science Support
303-497-2634                    P.O. Box 3000
address@hidden                Boulder,CO 80307-30000