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20050504: could not get the McIDAS shell programs



>From: "Mekonnen Gebremichael" <address@hidden>
>Organization: Pratt School of Engineering, Duke University
>Keywords: 200504201601.j3KG1gv2005753 McIDAS access

Hi Mekonnen,

>After a long hassle, mcidas is now up and running. It is my first time ever
>to use mcidas. So I downloaded the user's guide, and skimmed through it. But
>I still have difficulty performing the basic operations, like opening files,
>viewing data, etc. So I am turning to you for help.

The one big concept in McIDAS that users have to get used to is the "indirect"
access to data through the ADDE.  In McIDAS, data requests are sent to server
processes that handle the file access for you.  Those server processes can
be run out of:

- your own McIDAS session if the datasets are local to your account
- from a remote server running on the same machine if the datasets are
  accessed by a different user
- on a remote machine accessible through TCP/IP Ethernet

Because of this design, the end user (you) have to stop thinking in
terms of "I want to open and read that file" and start thinking in terms
of "I want to access that member of a dataset".  The thing that is not
intuitive is the step where someone (you, your McIDAS administrator, or
a McIDAS administrator for a different machine) configures a dataset.
The configuration step is one of "teaching" McIDAS which files reside
in what dataset.  This is done through the use of a McIDAS command known
as DSSERVE.  To get a quick start, run the following from your McIDAS
session:

HELP DSSERVE

The access to data through servers is known as the Abstract Data Distribution
Environment (ADDE).  Datasets in ADDE are just what you would think: sets
of data.  Those sets can be composed of like data (e.g., GOES imagery, model
output grids, NEXRAD radar image products, point source data, etc.) or
disparate data.

ADDE datasets are organized by 'group's.  A group is further organized
by 'descriptor's.  An ADDE 'group' can have a variety of types of data
(like for a case study).  A 'group+descriptor', however, can only have
one type of data.  The major types of data are IMAGE, GRID, TEXT, or POINT.

The naming of an ADDE dataset is 'group/descriptor'.  There are rules for
what characters are allowed in both the 'group' and 'descriptor' names;
see the online help for DSSERVE (HELP DSSERVE) for details.

A McIDAS command requests an element of a set from an ADDE dataset
group/descriptor.  On top of that, a setting in the user's McIDAS
session tells the command where the dataset 'group' lives (i.e., on
which machine).

>The file that I am interested in is "globir.02182.0015", it is a GOES-IR
>image. I have attached the readme file associated with this data. My
>question to you is: could you tell me, step-by-step, on how to view the
>image and the data?

OK.  Assuming that your file is in the McIDAS AREA format, you would
setup access to it by defining an ADDE dataset in which it exists.
As an example, let's call your ADDE dataset group 'TEST'.  Let's further
create a subset of the group 'TEST' and name it 'IMAGES'.  Here is
a simple example of the creation of a dataset TEST/IMAGES in which your
image can be found:

- assume that your file is located in the directory /data/images;
  you have already said that it is named globir.02182.0015

<from your McIDAS-X session>

DSSERVE ADD TEST/IMAGES AREA DIRFILE=/data/images/goesir.* "Test GOES IR image

Assuming that the image _is_ in McIDAS AREA format, and assuming that it _is_
readable by you, you should now be able to list out information about it:

IMGLIST TEST/IMAGES
IMGLIST TEST/IMAGES FORM=ALL

The listing(s) will tell you if you are able to read the file and if it is
indeed in McIDAS AREA format.  If the image is multibanded (more than one
wavelength channel in it), you will need to specify the BAND= keyword in
order to display what you want.  here is an example that assumes that
the image really is a GOES IR thermal (band 4) image:

IMGDISP TEST/IMAGES.1 BAND=4

Next blow it down:

IMGDISP TEST/IMAGES.1 BAND=4 MAG=-3

Please consult the online help for the meaning of the BAND= and MAG=
keywords for IMGDISP.

Also, it would be most useful if you would work through the McIDAS-X Learning
Guide as this has everything noted above and lots more on how to use McIDAS.

>Thanks much for your help,

No worries.

>p.s. please omit this email from appearing in the official Q&A site of your
>page. 

I will do as you request, but am curious as to why you want the transaction
omitted from our online tracking?  Our idea is that new users should be able
to benefit from transactions of past users and, thereby, bypass the need
to contact support directly.  When users choose to not have their inquiries
listed in the online system, it prevents others from learning from their
questions, so it makes our support job less likely to reach a wide audience.

Cheers,

Tom
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