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20010212: creating a mosaic in McIDAS

>From: address@hidden (Chris Hennon)
>Organization: Ohio State
>Keywords: 200102121741.f1CHf4L28141 McIDAS mosaic IMGREMAP

Chris,

>I'd like to create a single image of the tropical Atlantic by merging
>GOES-8 with meteosat-7.  If I remap both area files to the same
>projection, do you think I would have any trouble creating a merged gif by
>using image processing software like ImageMagick?

You can do the compositing with McIDAS directly.  If the ultimate
objective is to get a GIF (tm) image to use with some other display,
then this is easily done with the FRMSAVE command in McIDAS.

>Do you know if people have tried this before?

No, not really.  If one is already using a package that can do the
image processing desired, there is no real need to switch to the use
of a different package.

>The cover of this months AMS bulletin shows a
>global image of IR satellite - pretty cool stuff.

Right.   This is easily done in McIDAS.

>Can a rookie like me do
>something like that with two satellites?

Yup, and very easily.

>I have a feeling there are some
>more complex issues I have to worry about here.  Thanks for any help.

The job of compositing in McIDAS is as simple as:

o create an AREA that covers the region of interest
o remap one image into the that AREA
o remap the other image into the same AREA that the first was remapped
  into

There are a number of ways of doing the compositing.  For a view of
a couple of this, do the following:

DATALOC ADD RTIMAGES ADDE.UCAR.EDU
SF 1
IMGDISP RTIMAGES/GEW-IR LATLON=35 100 EU=IMAGE REFRESH='EG;MAP H'
SF 2
IMGDISP RTIMAGES/GWE-IRTOPO LATLON=30 100 EU=TOPO

The first example above remaps GOES-East and GOES-West into a
METEOSAT image whose subsatellite point has been moved to about
30,100.

The second example shows the combination of a topography image and
the "cloudy bits" from GOES East and West IR images.

The Unidata McIDAS distribution includes an application that sites use
to combine GOES-East and West images like you see above.  It also
includes two McBASI scripts, GEWCOMP.MCB and GEWCOMP1.MCB, that show
how one may do compositing using ADDE datasets.  You could adopt either
of these and come up with an easily run process that would do the
compositing in McIDAS.  Then you could display the image and turn it
into a GIF for display elsewhere.

Tom