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[McIDAS #OBW-844755]: IMGREMAP



Hi Kwan-yin,

re:
> How are you doing?

I am doing well, thanks.  How about you?

re:
> I have a question about image remapping that I would
> like to ask.  I am trying to remap a MTSAT 2 image, which is centered at
> the equator and 145E, to one that is centered at 140E.  I do not have a
> MTSAT 1 image (at 140E) for me to do IMGREMAP PRO=DEST.  Is there a way I
> can remap the image to a different satellite position?

Yes, it is very easy to remap into a different projection using McIDAS-X;
all you need is an image with the desired navigation.  For this purpose,
a METEOSAT image is the best place to start.  Why?  Because METEOSAT
images use an idealized satellite projection where the sub-satellite
longitude is readily available in the AREA file header.  the Unidata
McIDAS-X distribution contains a METEOSAT image, AREA9012, that has
had its sub-satellite longitude changed from 0 (zero) to 100W.  We have
long used this image in training workshop exercises for image remapping.

The for modifying the sub-satellite longitude in the AREA is simple in
McIDAS-X:

<in an interactive McIDAS-X session>

DSSERVE ADD MYDATA/IMAGES AREA 1 9999 "All AREA files    <- first, create a 
dataset to access
                                                            any/all images in 
AREA format
IMGCOPY MYDATA/IMAGES.9012 MYDATA/IMAGES.3000 SIZE=SAME  <- IMGCOPY will insure 
that the copy has the
                                                            endianess of the 
local machine
LWU POKE AREA3000 -1400000 70                            <- change central 
longitude; lon * 10000
                                                            (NB: McIDAS LON 
format is west positive!)
ERASE
IMGDISP MYDATA/IMAGES.3000 LATLON=-140 0 MAG=-2          <- take a look
MAP SAT; MAP LALO INT=5 5

NB: AREA9012's resolution is perhaps not what you want (it is nominally
9 km).  You can change this by modifying the AREA header (in the copy
of the file):

- 1-based AREA header word  9 == # lines in image
- 1-based AREA header word 10 == # elements in image
- 1-based AREA header word 12 == line resolution
- 1-based AREA header word 13 == element resolution

Or, you can change this using your IMGREMAP invocation.

NB: You must make all of the changes to the copy of AREA9012 before
remapping your MTSAT image into that image.

Here is an example of the eventual remap:

IMGREMAP MYDATA/IMAGES.1000 MYDATA/IMAGES.3000 SIZE=ALL

After doing the IMGREMAP, you will likely need to change some more
header values in the destination image so that it is recognized as an
MTSAT image.  Check out IMGCHA for details.

re:
> In another note, I came across the SSEC McIDAS archive site
> http://www.ssec.wisc.edu/datacenter/ngarc_no_smart_server_info.html#MTSAT_1R
> and
> I would like to know how one may subscribe or gain access to the archive.

As you have no doubt learned, the satellite archive that SSEC maintains is
not open for general access.  Unidata _university_ sites, however, have
been allowed to access up to 5 GB of satellite data from the SSEC archive
per month.  Unfortunately, this access does not extend to NOAA 
personnel/offices.

If you want to pursue access to the SSEC archives, I recommend that you send
email to the Data Center folks there:

address@hidden

NB: this access will not be free for NOAA access.

re:
> Thanks again for your help.

No worries.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: OBW-844755
Department: Support McIDAS
Priority: Normal
Status: Closed


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