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This is a simple introduction to the HPCVL installation of
the Numerical Algorithms Group (NAG)
visualization software called "Iris Explorer". Documentation for
this system is available online on our machines, and this FAQ is
only meant as a basic introduction to its use on HPCVL computers.
Contents
What is Iris
Explorer?
The Iris Explorer is a very powerful visualization tool. It is
designed in a modular manner to offer maximum flexibility. The Iris
Explorer is provided and licensed by the Numerical Algorithms Group
(NAG). In this FAQ we can only scratch the surface of its
capabilities, and have to refer to the
User's Guide for a more detailed treatment.
Which version of the
Iris Explorer is currently in use in HPCVL machines? The
current version of the Iris Explorer software on HPCVL machines is
Release 5.0
Where does the Iris
Explorer Reside?
Like most "optional" software on SUN systems, the Iris
Explorer is located in the /opt directory hierarchy. The
directory root is shared with the other NAG software (i.e.,
libraries): /opt/nag/ The software
itself is located in /opt/nag/explorer/bin.
How do I Setup my
Environment to use the Iris Explorer?
The program requires the setting of the
environment variable LM_LICENSE_FILE to work. Since it calls
a Graphical User Interface, you will also have to set DISPLAY
to make sure the graphics goes to your terminal. For
csh: setenv LM_LICENSE_FILE
/opt/nag/license/license.dat
setenv DISPLAY
ip_address:0 where ip_address
stands for the IP address of your terminal, workstation, or
PC.
Often it is necessary to set the following graphics variable to
ensure proper operation:
setenv CXGLTYPE mesagl
This might not be necessary if your client machine has the
proper graphic libraries installed. To be on the save side, it is
best to include it.
It is also necessary to set several other enviroment
variables. Those are collected in the sample.cshrc file in
/opt/nag/explorer, and may be accessed by "sourcing" that
file; in csh: source
/opt/nag/explorer/sample.cshrc
Then, the program can be started by typing
"/opt/nag/explorer/bin/explorer".
Alternatively to this sequence of setup commands, you may rely
on the usepackage facility to set up your system for Iris
Explorer. By typing
use explorer
at the command prompt, or including this command in your
.login or .profile file, the above setup commands
will automatically be applied to your shell and Iris Explorer can
then just be started by typing "explorer &". Note that the
DISPLAY environment variable may still have to be set
manually.
How is the Iris
Explorer Licensed?
HPCVL has a license agreement with the Numerical Algorithms
Group. This license allows Iris Explorer to be executed on our
machines without restrictions on the number of processes or
seats. The presence of a valid license is checked at
runtime. This means that a license manager is automatically
invoked everytime Iris Explorer is executed. This license manager
will then check the system for a presence of a license file which
uniquely identifies the machine.
Our agreement with NAG includes the unique opportunity for HPCVL
members to download and use the Iris Explorer on their own
workstations. Individual license keys will be required for this,
and will be issued by us on a temporary basis. The validity of the
license key is limited by the duration of our agreement with NAG,
and of your membership with HPCVL. Within these terms, you can
freely use the software on an arbitrary number of machines. Note
that we also require our users to sign a statement that they are
HPCVL members, that the license keys will not be copied and passed
on to third parties, and that the usage of the software will be
non-commercial and serves research purposes. Find a copy of the statement here,
and return it to us signed to be issued a license key. Note that
the statement extends to all NAG software, i.e. it includes the NAG
libraries as well. Here is a list of
sites for direct download of the software can be found
here.
After
the program was set up properly , it can be
started by simply typing
explorer &
The ampersand enures that the explorer process is detached from the
command prompt, i.e. it runs in the background and your terminal
may still be used.
When you start the program, you will
be presented with three windows: the Librarian, the
Editor and a Log window. The program uses a
"toolbox" principle.
In the librarian window you
will find a large number of modules, which perform certain simple
tasks, such as reading in data from a file, or calculating a
function of several variables, or displaying graphics. You can
click-and-drag those modules to the editor window to build a
map. The librarian window also includes quite a few fully developed
task maps that can serve as examples.
The editor window is the main
component of Iris Explorer. Here you arrange modules that perform
simple tasks to a network called a map. The output of one module
may be connected to the input of another, and with this map you are
able to specify the overall visualization tasks that you may want
to have performed. Here is an example (from the pre-made maps that
come with the program):
The map "Simple" is meant to display a
so-called isosurface of a three-dimensional distribution, ie, the
set of all points that share a specific value of that
distribution. This is done in the simplest possible manner by
reading the distribution in from disk and constructing the
isosurface from those data. The map consists of three component
modules: ReadLat, IsosurfaceLat, Render.
ReadLat has no input channel, and consists only of a GUI
that lets the user specify which “lattice” file
contains the needed data for the distribution. A lattice is a
special data structure used in Iris Explorer to specify data
of various complexity, dimensionality and connectivity. Such data
might be generated by a program or by another module.
ReadLat has one output channel through which it passes the
lattice on to the next module.
IsosurfaceLat produces a specified isosurface from a 3D
lattice. It has one input channel for a 3D lattice representing a
three-dimensional distribution, and one output channel for a
surface geometry. A surface geometry is a graphical object
which may be displayed. There are a few adjustable parameters which
might be passed to this module via a GUI, e.g. To specify the value
of the isosurface.
Render is the standard renderer in Iris Explorer,
and excepts several types of input, one of them being
geometries. It has a variety of adjustable parameters which
may be adjusted via a GUI, and have to do with the rendering of
objects that are being displayed by this module, for instance
colors, light sources, orientation, size, perspective, etc. The output of each of these modulkes is
connected to the input of the next one, giving a chain ReadLat
> IsosurfaceLat > Render. It is at any point possible to
switch in or add additional modules, for example to produce a
bounding box, axes, cuts, annotations, etc. Iris Explorer
comes with a large number of example maps a prepared
modules. However, it is relatively simple to write additional
modules and integrate them into the program, for example to let you
convert the output data from your favourite program into a
"lattice" that can be processed by Iris Explorer's
modules.
NAG software is very well documented. For Iris Explorer online
documentation is available in form of the
User's Guide . We are holding a hard copy of the entire NAG
doumentation at our Kingston office (993 Princess St.) as
well.
Some level of support is also part of our
agreement with NAG, so if you contact us we can forward your
questions and concerns.
HPCVL also
offers user support; for questions about this FAQ and the usage of
the NAG libraries on HPCVL machines contact us .
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