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[McIDAS #MMD-610472]: 20140718: Problem matching projections between McIDAS and Terascan



Hi Greg,

re:
> Thanks - I misremembered which was bigger but you're right, the pixel
> size is smaller in the McIDAS remapping and that confirms my suspicions.

Yup.

re:
> It's a bit disconcerting that the RES parameter is not very exact in this
> case.

I agree!

re:
> I'm wondering if I can multiply it by 1.3 to force the pixel size to
> be what I want it to be? What do you think?

I just tried it, and it seems to have worked:

IMGREMAP EAST/CONUS.84 MYDATA/IMAGES.3000 PRO=MERC LATLON=39.25 105.0 RES=1.3 
SIZE=925 1048 SSIZE=ALL BAND=1
 ...

IMGLIST MYDATA/IMAGES.3000 FORM=ALL
Image file directory listing for:MYDATA/IMAGES
 Pos Satellite/         Date       Time      Center      Res (km)   Image_Size
     sensor                                 Lat  Lon    Lat   Lon
 --- -------------  ------------  --------  ---- ----  ----- ----- ------------
3000  G-13 IMG      21 JUL 14202  20:15:00    39  105
   Band: 1    0.63 um VIS Cloud and Surface Features    1.00  1.01   925 x 1048
     proj:    0 created: 2014202 230618  memo: RT GVAR

     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:  0 avg-smp: N
     start yyddd: 2014202  start time:201519  start scan:  406
     lcor: 5879  ecor:  9477  bytes per pixel: 1  ss:180
     Resolution Factors (base=1):   Line=    1.0   Element=    1.0
IMGLIST: done

A visual comparison between the Terascan remapped image you sent earlier and
this one from McIDAS shows that the latitude/longitude map lines are slightly
different. A scaling of 1.29 results in displays that are pretty darn close.
The ratio 1/0.77 is actually 1.2987; you may want to give it a try also.

re:
> We have a mapping tool preconfigured with a specific bounding box so it
> would be nice to create both Terascan and McIDAS imagery with the exact
> same bounds so we can easily switch between the two sources without having
> to reconfigure the display each time.

Give the scaling trick a try and let me know how the result compares with
the Terascan remaps.

re:
> Thanks for your help,

No worries.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: MMD-610472
Department: Support McIDAS
Priority: Normal
Status: Closed


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