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[McIDAS #XCP-875731]: Area Files

Hi Paul,

> Long time no see! I hope all is well in your neck of the mountains!

Well, it has been raining for over 12 hours now, and there are flash
flood concerns for the creeks that were inundated last fall...\

> We are currently working on a project to use our McIDAS satellite imagery
> but use GEMPAK to do more objective analysis as overlays on it. We fell
> that McIDAS is too limiting for what we would like to accomplish.

OK.  McIDAS' real strengths are on the satellite imagery side, not on
the model output side like GEMPAK's.

> So the concern is how do we take the McIDAS image coordinates and translate
> them to GEMPAK? When I generate my sat images, I use the center point in
> lat/lon on a 800x600 frame size. Gempak seems to want the lower left and
> upper right points with latitude and longitude.

Yup.  It is interesting that GEMPAK uses the lower left and upper right
points and McIDAS uses the lower right and upper left.  I have no idea
why the GEMPAK folks adopted the other convention even though McIDAS'
was well established.

> Is there a way to convert
> via simple math to get those points?

In McIDAS yes, sort of.  Outside of McIDAS, not really.  The reason I say this 
that one has to go through the navigation transform to get the Lat,Lon of any
point in Line,Element space.

Off of the top of my head, I would think that the following commands would
be used to determine the Lat,Lon of any given point:

IMGLIST  - to find out the "shape" of the image in question (i.e., #lines
           and #elements)

IMGDISP  - to display the image

           This could be to a frame created in a script

PC       - to position the cursor at a particular Line,Element point

E        - to list out the Earth coordinates (Lat,Lon) of the Line,Element

           The tricky part is if the pixel at Line,Element is not out in

It strikes me that there must be a McIDAS routine that allows one to do the
above in one go, but it is not coming to mind at the moment.  I will need
to poke around to see if I can find the program that I am semi-remembering.


- presumably all pixels in the plots you want to produce will be navigable

  What happens if one or more corners of the particular image are not

> Ultimately we want GEMPAK to be
> working with the same map coordinates as McIDAS so the data is accurately
> placed on the satellite image.

I understand.

> I am also concerned with the bottom label in McIDAS as to whether or not
> that changes my question.

??? I do not know what you mean by this comment.  The label displayed by
IMGDISP will not be available in GEMPAK, but GEMPAK has the ability to
annotate displays in its own way.

> I hope this explains what we need.

Aside from you last comment, yes.

> Thank you

No worries.


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Ticket Details
Ticket ID: XCP-875731
Department: Support McIDAS
Priority: Normal
Status: Closed

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