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[McIDAS #VTR-898959]: LWU



Hi Mary Ellen,

re:
> we're OK with respect to "endienness" See my lwu.k result here:
> 
> address@hidden dec]$ lwu.k LIST AREA1006 0 64
> 0.          0           4 HEX:        0        4 ASCII:
> 2.         52      111060 HEX:       34    1B1D4 ASCII: 4
> 4.       1500        9901 HEX:      5DC     26AD ASCII:       &
> 6.       9901           1 HEX:     26AD        1 ASCII:  &
> 8.        200         200 HEX:       C8       C8 ASCII:
> 10.          1           1 HEX:        1        1 ASCII:
> 12.          1           1 HEX:        1        1 ASCII:
> 14.          0           0 HEX:        0        0 ASCII:
> 16.     111342      174351 HEX:    1B2EE    2A90F ASCII:
> 18.        256           0 HEX:      100        0 ASCII:
> 20.          0           0 HEX:        0        0 ASCII:
> 22.          0           0 HEX:        0        0 ASCII:
> 24.  541545293  1635017060 HEX: 2047534D 61746164 ASCII: MSG  data
> 26. 1869768224  1381507181 HEX: 6F726620 5258206D ASCII:  fro m XR
> 28. 1444959305   538976306 HEX: 56205449 20202032 ASCII: IT V 2
> 30.  538976288   538976288 HEX: 20202020 20202020 ASCII:
> 32.       1006         768 HEX:      3EE      300 ASCII:
> 34.        256           0 HEX:      100        0 ASCII:
> 36.          0           0 HEX:        0        0 ASCII:
> 38.          0           0 HEX:        0        0 ASCII:
> 40.          0           0 HEX:        0        0 ASCII:
> 42.          0           0 HEX:        0        0 ASCII:
> 44.          0      111060 HEX:        0    1B1D4 ASCII:
> 46.       1500           0 HEX:      5DC        0 ASCII:
> 48.          0           0 HEX:        0        0 ASCII:
> 50.          0  1381189974 HEX:        0 52534956 ASCII:      VISR
> 52. 1414091330           2 HEX: 54495242        2 ASCII: BRIT
> 54.          0           0 HEX:        0        0 ASCII:
> 56.  541545293   538976288 HEX: 2047534D 20202020 ASCII: MSG
> 58.          1           0 HEX:        1        0 ASCII:
> 60.          0           0 HEX:        0        0 ASCII:
> 62.          0           2 HEX:        0        2 ASCII:
> 64. 1413694802           0 HEX: 54434552        0 ASCII: RECT

Very good.  This should make things much easier.

re:
> 
> Apparently, I'm missing something quite obvious...What parameter number has
> the date and time stamp?

AREA header words 4 and 5 (1-based; words 3 and 4 for 0-based) contain
the image date (in yyyjjj) and time (in hhmmss), respectively.  LWU works
with 0-based indexing, so to change the date from 111060 to 111061, you
would run:

LWU POKE 111061 3

Similarly, to change the time, you would run:

LWU POKE 1600 4

to change the time from 1500 (which represents 00:15:00) to
1600 (which would be 00:16:00).

re:
> I'm looking at an image for Sep 1, 2011 at 00:15
> utc and don't "see" the values in the LWU output anywhere (imglist results
> below).

Your LWU listing shows this:

lwu.k LIST AREA1006 0 64
0.    0      4 HEX:   0     4 ASCII:
2.   52 111060 HEX:  34 1B1D4 ASCII: 4
4. 1500   9901 HEX: 5DC  26AD ASCII: &

The second line contains 0-based AREA header words 2 and 3. Word
3 is the date in yyyjjj (jjj is the Julian day of the year).
The third line contains 0-based header words 4 and 5, and word
4 is the time of the image in hhmmss.

re:
> Years ago I had a listing of what all the LWU parameters
> meant...don't see that online anywhere today.

This is included in the Unidata McIDAS distribution as the file
area.doc in the HELP directory, ~mcidas/help/area.doc.  In the
same directory is the file area2.doc.

re:
> My imglist results below just
> don't seem to coincide with the LWU output, other than sector 32 which is
> the AREA number 1006. MMMM, this is a remapped image via imgremap.
> 
> imglist.k MEC/TEMP.7 FORM=EXP
> Image file directory listing for:MEC/TEMP
> Pos Satellite/         Date       Time      Center      Res (km)   Image_Size
> sensor                                 Lat  Lon    Lat   Lon
> --- -------------  ------------  --------  ---- ----  ----- ----- ------------
> 7  METEOSAT9      1 SEP 11244  00:27:00    28   17
> Band: 1    0.6 um VIS Cloud and Surface Features     4.00  3.53   200 x  200
> proj:    0 created: 2011347 221748  memo:
> type:VISR     cal type:BRIT
> offsets:  data=     768 navigation=  256 calibration=    0 auxiliary=    0
> doc length:   0   cal length:   0   lev length:   0 PREFIX=   0
> valcod:          0 zcor:  1 avg-smp: N
> lcor: 9901  ecor:  9901  bytes per pixel: 1  ss: 52
> Resolution Factors (base=1):   Line=    1.0   Element=    1.0
> imglist.k: done

Hmm... 0-based words 45, 46 and 47 are supposed to be:

    W46.  Actual image start year and Julian day, yyyddd
    W47.  Actual image start time, hhmmss; in milliseconds for POES data
    W48.  Actual image start scan

NB: W46., W47. and W48. are 1-based

re:
> I'll take a look at the raw image using lwu.

Is it possible that the image you are listing with LWU is not
the one you are listing with IMGLIST?  This would explain the
discrepancy you are seeing.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: VTR-898959
Department: Support McIDAS
Priority: Normal
Status: Closed


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