20001109: IMGREMAP: MAG= vs RES= (cont.)

>From: Jason Allard <address@hidden>
>Organization: PSU
>Keywords: 200010240345.e9O3jC425238 McIDAS-X IMGREMAP MAG RES

Jason,

Sorry it has taken so long for me to get back to you, but we had meetings
at the end of last week and then had to move out of our offices (for
six weeks no less).

>Greetings, again... I'm sorry I haven't responded to the previous
>discussions we've had.  I've been out of town and unable to devote the
>time needed to this.  I regret this not getting back to this because
>with the time that passed, you may have forgotten what we've talked
>about and that could make it more difficult to get back on tract.

It is true that it would be hard to recall all of our past conversations
if it were not for our online tracking system.  You can review what
transpired before by using the search key 'allard' in the web page:

http://www.unidata.ucar.edu/glimpsedocs/ghmcidas.html

>Because of that, I've included the last e-mail (for backgroud).  Once
>again, thanks for the help.

>I think this confusion was my fault... I didn't discuss what I was
>doing very clearly.  Let me see if I can clarify this.  I believe that
>I should actually use the REDIRECT command as I mentioned above.  I
>have actual images located in /fractal/s2/allard/goesdata/weakflow
>Within that directory are the weak flow images.  I think 'linked' the
>physical location of the data with another directory by doing (this in
>one example:
>
>ln -s /fractal/s2/allard/goesdata/weakflow/1991/199105100001.goes7ir     /frac
> tal/s2/allard/mcidas/weak/AREA1;
>(the above is all one line).

Before we go too far here, I must point out that the file name AREA1 is
not a legal McIDAS one.  McIDAS image files are named AREAnnn, where
'nnnn' is a 4 digit number from '0001' to '9999'.  A correct version of your
link would be:

ln -s /fractal/s2/allard/goesdata/weakflow/1991/199105100001.goes7ir 
/fractal/s2/allard/mcidas/weak/AREA0001

>When I go to
>/fractal/s2/allard/mcidas/weak I see AREA1.  I've linked the physical
>location of the actual images to the AREA file 1 in another directory.

I understand your intention, but you must make the link conform to a valid
McIDAS file name before you can proceed.

>So, earlier, when I mentioned that I need to do the REDIRECT command:
>
>REDIRECT ADD WEAK "/fractal/s2/allard/mcidas/weak
>
>I was telling mcidas where the mcidas data files are.

Again, I understand your intention, but the REDIRECTion facility of McIDAS
tells McIDAS where to find files of a certain name.  You, therefore,
need a REDIRECT command like:

REDIRECT ADD AREA0001 "/fractal/s2/allard/mcidas/weak

if that is, in fact, where the file AREA0001 is to be found.  So, you
need to come up with a naming convention for the set of files that you
want to place in the /fractal/s2/allard/mcidas/weak directory.  For
the purpose of this discussion, let's assume that these files are
named AREA0001 - AREA0100.

>I don't think I
>described that well enough, and that's why you got the impression you
>did (... of course, I could still be wrong).  Basically, I did this so
>that when I'm working with weak flow data, whether it be the original
>image, the subsetted image, or the new image created with the program I
>have, the new weak flow AREA created will always go into the WEAK
>directory as long as that is the only REDIRECT I have active.

Your objective was correct, but what you have to do in McIDAS is more
involved.  Again, you have to define the set of AREA files that will
be accessible and create a REDIRECTion for the set.  Another example
is needed:  Let's suppose that you have 13 files that you want to
access (read/write/etc) in a single directory.  Furthermore, let's
assume that this set is AREA0001 - AREA0013.  The REDIRECTions that
would identify this list for you are:

REDIRECT ADD AREA000* "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0010 "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0011 "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0012 "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0013 "/fractal/s2/allard/mcidas/weak

>Along
>this logic, I could do the same for the best weak flow and strong flow
>days... making sure I only keep the appropriate REDIRECT open.
>Correct?

Almost.  You need to divide up the file namespace for the various data
sets so that the names of one set are not the same as those of another
set.

>At this point, it was my intention to use the DSSERVE command to assign
>AREAs for my original data (as I mention below in the last e-mail).

The DSSERVE command assigns a dataset group name and descriptor to
a set of files.  The files themselves must be "findable" by McIDAS.
The "findability" of the files is where the REDIRECT command comes
in.

>I was going to do that with the commands:
>
>For the original data:
>
>DSSERVE ADD WF/051091VIS AREA 1 13
>DSSERVE ADD WF/051091IR AREA 14 37

This is fine in of itself.  I would say that the best organization of
these files is for AREA0001 - AREA0013 to be in one directory; AREA0014
- AREA0037 to be in another.  The DSSERVE command then tells McIDAS to
look for AREA001 to AREA0013 (inclusive) when the dataset WF/051091VIS
is referenced.  Likewise, the images in AREA0014 - AREA0037 will be
used when the dataset WF/051091IR is referenced.

>and for the subsetted data (created with the IMGREMAP command):
>
>DSSERVE ADD WFSUB/051091VIS AREA 3001 3013
>DSSERVE ADD WFSUB/051091IR AREA 3014 3037

OK, in the exact same way as above, McIDAS must be told where to find
AREA files AREA3001 - AREA3013 and AREA3014 - AREA3037.  You would do
this with REDIRECT commands like the ones I listed above.

>The first two DSSERVE commands are in essence 'labelling' AREA files
>that already exist,

Yes.

>while the second two DSSERVE commands are creating
>the 'labels' for AREAs that will be created with the IMGREMAP command
>later on.

Yes, but McIDAS must be told where to access those files.

>I wish I had been able to keep up the exchange of e-mails two weeks ago
>so that this was a lot clearer to you.

I am pretty sure that I understand what your intentions are.  What is
missing right now (but oh so close) is your understanding of what you
have to do in McIDAS to get things working.

>If what I've given you still
>doesn't make sense, even with the attached past e-mail below, let me
>know and I'll try take a couple steps back in what I was trying to
>explain so that I can refresh your memory.

No, I understand.  The next step is for you to understand what a
REDIRECTion really is.  The easiest way to get this understanding
is to do some experiments.  Here is what I suggest:

Assume that you are eventually going to want to access some images
in a directory called /fractal/s2/allard/mcidas/weak, but that
directory does not yet exist (delete it if it does; this will really
help you see how things work).

First, create the directory called /fractal/s2/allard/mcidas/weak, but
do NOT put any images in it yet.  Let's assume that you will put
images in AREA files in this directory, and that they will be named
AREA0001 - AREA0013.

Next, run the McIDAS DMAP command to locate the file AREA0002:

DMAP AREA0002

This listing may or man not come back as empty, but it should definitely
NOT come back showing that AREA0002 is in /fractal/s2/allard/mcidas/weak.
Why?  Because, the directory is empty.

Next, copy AREA0002 to /fractal/s2/allard/mcidas/weak (or make a link
from something like 
/fractal/s2/allard/goesdata/weakflow/1991/199105100001.goes7vis to 
/fractal/s2/allard/mcidas/weak/AREA0002).

Rerun the McIDAS DMAP command:

DMAP AREA0002

The listing should still be empty or it should indicate that the file AREA0002
can be found in a directory that is different than
/fractal/s2/allard/mcidas/weak.  Why?  Because McIDAS doesn't know to look
for AREA0002 in /fractal/s2/allard/mcidas/weak.

Next, tell McIDAS that it can find AREA0002 in /fractal/s2/allard/mcidas/weak:

REDIRECT ADD AREA0002 "/fractal/s2/allard/mcidas/weak

Now, redo the DMAP command:

DMAP AREA0002

McIDAS should now see AREA0002 in the /fractal/s2/allard/mcidas/weak
directory.  Why?  Because you have taught McIDAS where to look when
trying to access the file AREA0002.

Building on this, copy (or make links) for the set of images in AREA0001 -
AREA0013 in the directory /fractal/s2/allard/mcidas/weak and tell McIDAS
to look for those files there:

REDIRECT ADD AREA000* "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0010 "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0011 "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0012 "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA0013 "/fractal/s2/allard/mcidas/weak

If you decided that you might have 20 images in this set, the REDIRECTions
would be simplier:

REDIRECT ADD AREA000* "/fractal/s2/allard/mcidas/weak
REDIRECT ADD AREA001* "/fractal/s2/allard/mcidas/weak

Once your McIDAS session can correctly locate the data files, you can
tell it how to access them using ADDE dataset names:

DSSERVE ADD WF/051091VIS AREA 1 13 "Weak flow images

After doing this, you should be able to list out information on the
images using the ADDE IMGLIST command:

IMGLIST WF/051091VIS.ALL

>Once again, thanks for all the help...

Once you understand how to use the REIDRECT command to tell McIDAS
where to look for specific files, you will be well on your way to
doing the analysis you want.  Please don't hesitate to ask questions
when things seem confusing or too mysterious.

Tom