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[McIDAS #LZE-711095]: glmtools ABI gridded data with McIDas



Hi

re:
> Thanks for all the feedback.

No worries.

re:
> I was not asking if I could combine three AREA files, I already know how
> to do that. Sorry for the misunderstanding.  We use these for
> combining color channels to make a true color type image.

Exactly, that was why I was interested in how you were going to use
the COMBINE application for the GLM composites.

re:
> What I was interested in knowing if I could do, was overlaying the ABI
> gridded glm image (or should I say glm plot) on top of the RGB image
> from the three AREA files, and if so if I can use a transparency factor
> when doing so (you answered both these questions I think unless the GLM
> gridded imagery is not considered an 'image' and can be considered
> 'grid' data, though I am not so sure I would know what to do with that
> 'grid' data).

McIDAS-X does not provide this kind of functionality, at least not
easily.  McIDAS-V and the IDV, on the other hand do this kind of
thing easily.  I routinely use either both of these applications
to create the kind of displays you describe, and I make good use
of the ability to change the transparency of the various layers.

re:
> Of course one can make the images and overlay elsewhere, but the mag and
> res need to be in sync, and the line widths of maps can be problematic
> if cutting sectors from a full disk rasterized image with maps unless
> separate maps are made to go with different mag and resolutions.

Have you tried using McIDAS-V or the IDV for doing this?  If not,
I suggest that you give it a try as the underlying VisAD layer
that they are built on top of does all the work of adjusting
spatial domains and matching resolutions.  The displays are
really quite nice!  Also, I use McIDAS-V/IDV in conjunction with
McIDAS-X in that I setup ADDE datasets in McIDAS-X of the various
images that I want to work with and then access those datasets
from McIDAS-V/IDV.

re:
> I am actually trying to understand how the mag and res relate to each
> other.

In McIDAS-X, the MAG concept is a function of the base resolution of
the instrument that scanned the image.

re:
> for 1km (nadir) ABI gridded data a FD resolution of 10848x10848 at a mag
> of 1 would be 1km pixels (more or less).

Yes.  The resolution quoted for images in McIDAS is the resolution 
at the subsatellite point.  The resolution of pixels away from this
point can be calculated.

re:
> I know a mag of 4 is twice the magnification of 2, and a mag of -4 is
> twice zoomed out as -2, but I am not so sure what -1 is or how 1
> relates to 2.ÂÂ I have not done that with trial and error yet.

In McIDAS-X, MAG= specified in an IMGDISP invocation specifies
how to sample the pixels from the image:

MAG= >  1 says to replicate the pixels
MAG= < -1 says to sample the pixels

So, specifying something like:

IMGDISP RTGOESR/FD BAND=2 MAG=-2 -2 ...

says to load/display ever 2nd pixel from the original image in both
the Line (Y) and Element (X) directions.  MAG=-3 -3 says to sample
every 3rd pixel in both directions, etc.  MAG=2 2 says to replicate
the pixel displayed in each direction.

re:
> Thanks for all the feedback.

No worries.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: LZE-711095
Department: Support McIDAS
Priority: Normal
Status: Closed
===================
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