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NAG's IRIS Explorer™ - Frequently Asked Questions

This document is designed for users of IRIS Explorer with general questions. For more technical questions, or those that apply to a specific platform, please select one of the links provided in the right side box.

General Information

General Information - Answers

1. What is IRIS Explorer™? [Top]
   
   IRIS Explorer™ is a powerful visual programming environment for 3-D data visualisation, animation and manipulation. It is available on a broad range of PC and workstation platforms. OpenGL and Open Inventor are graphics libraries that bring the power of 3D graphics to developers. These products are some of the building blocks upon which IRIS Explorer is built.
   
   Modules can be plugged together in IRIS Explorer enabling users to interactively analyse collections of data and visualise the results for analysis, presentations or publication. Each module is a software routine that users select from the large library included in IRIS Explorer. Users can develop their own modules or use NAG's Consultancy Service to write modules tailored to their particular requirements. These modules provide an easy way to share functionality, without the need to understand the underlying program or algorithm.
2. What is new for Release 5.0? [Top]
   
   
   • Compiling groups. This allows users to create new modules in the IRIS Explorer Map Editor by combining existing modules together. This leads to performance improvements through the better use of system resources such as CPU and memory, and reduces the overheads associated with module communications.
   • More module source. Because the group compilation mechanism proceeds by returning to the source code of the constituent modules and compiling them together, IRIS Explorer 5.0 now contains the source to almost all of the modules in the distribution (prior to this release, only a subset was available as source). As well as as increasing the range of applicability of group compilation, this also provides users with a great deal more source, which can be modified or extended at will, or used as the starting point for new user-developed modules.
   • Internal performance enhancements. The internal architecture of IRIS Explorer has been overhauled at version 5.0. Processes in the core have been merged, and redundant duplication of functionality has been removed. In addition, the internal communications mechanism has been updated to use the native Windows interface on that platform. The result is faster communication between modules, which is particularly noticeable for maps that contain loops.
   • Module enhancements. Pyramid modules have been substantially improved in IRIS Explorer 5.0. These modules, which are used to visualize unstructured meshes (for example, from finite element analysis or computational fluid dynamics) using isosurfaces, contouring and slicing, have been rewritten to incorporate state-of-the-art algorithms. In tests, the new modules have run about fifty times faster than the old versions, offering users more interactive analysis of this type of data in IRIS Explorer 5.0. Additionally, more options for display have been added to the Legend, GenerateColormap and Render modules.
   • New modules. There are around 70 new modules in IRIS Explorer 5.0 (representing an increase of about 25% over the previous release). Particle advection for regular grids has been supplemented by modules which visualize vector data on an unstructured mesh (stored in the IRIS Explorer pyramid datatype) using particle advection. New geometry manipulation modules enable permanent changes to be made to, for example, the material properties of geometry in visualization scenes. Other new geometry modules allow for different types of clipping to be performed on visualization objects in the scene. A new module which reads column oriented ASCII text files (for example, data exported from an Excel spreadsheet as text) into an IRIS Explorer lattice has also been added at version 5.0. Other modules allow users to perform simple arithmetic operations on lattice data within an IRIS Explorer map, and new modules have also been added for the output of animations to MPEG files or output of scenes to a ray-tracer for alternative rendering of visualizations.
   • New tools. packmap takes a map file and builds a distribution containing the modules, data and IRIS Explorer components required for its operation on another machine. This gives developers a convenient way to share their application without distributing unnecessary parts of the system. QuickLat is a new tool in IRIS Explorer 5.0 that provides a simplified interface for building data reader modules. Working with QuickLat, the user specifies the form of the output lattice datatype together with other parameters such as input filenames. QuickLat then automatically generates template code in either C or Fortran which contains simplified hooks into the lattice data and coordinate arrays, and the user adds the code to read into these arrays, given the format of their input file. The last step is to compile and use the module to read the data into an IRIS Explorer map.
   • Improved help. A new interactive demonstration facility has been added to show users the answers to some frequently asked questions (FAQs) - such as "How do I save an image of my visualization?". The main interface to the demos is the new FAQ page in the documentation. The demos run within the Map Editor using the new ViewDemo module and contain a running commentary that explains what is happening in the map at each step. The user can step through the demo interactively, or leave it to play through automatically; finally, the demo can be paused at any point and the map saved for later recall by the user.
   • Module searching. A new search facility has been added which allows users to find all modules with a specific functionality (e.g. all modules which accept lattices and produce geometry). There is also the facility to search map files for specific modules.
   • Example maps. The number of maps has been substantially increased in this release, with the aim being to provide an example of the use of each supported module. Around 115 new maps have been added, which has increased the total number of maps by a factor of about 3.5, compared to the previous release of IRIS Explorer. The example map for a module is now part of its resources, and so is accessible from the module icon in the Module Librarian (as well as from the list of maps in the Maps category).
   • New interface. The Map Editor interface now defaults to coloring each connection according to the datatype which it is transferring between the modules. In addition, multiple connections between pairs of modules are displayed separately. The previous interface (all wires colored blue, single wires between modules) is still accessible, however.
   • Improved layout algorithm. The algorithm used for laying out the widgets in the Module Control Panel Editor has been improved to give greater consistency with the layout as displayed in the Map Editor. The treatment of Decorations (frames, separators) in the control panel has also been improved.
   • Hide parameter ports from port list. A new option has been added to the Module Control Panel Editor not to display individual parameter ports in the module port list. This can save space in the port list, especially if the module has a large number of parameters.
   • More robust API. The IRIS Explorer Application Programmer's Interface has been enhanced for this release with the explicit declaration of any pointer to a constant as 'const'. This makes it harder to modify pointers inadvertently (for example, module port names are now declared as 'const char *' in API routines).
   • New API routines. The routines which handled error checking after data allocation (specifically cxDataAllocErrorClear, cxDataAllocErrorGet, cxDataCheckErrorInfoDel, cxDataCheckErrorInfoGet, cxDataCheckErrorInfoMsgAppend, cxDataCheckErrorInfoNew, cxDataErrorMsgGet) have been replaced by a new routine, called cxDataManAbortOnError, which manages the error handling behaviour of the data manager.
   • Enhanced module building. The Module Builder now automatically generates a header file which contains a declaration of a prototype of the user function (as specified in the User Function pane of the Module Builder) along with any hook functions. Including the header file - which is called .uf.h - in the module source file ensures that the user function (and hook functions) in files are consistent with the details entered in the Module Builder.
   • Updated documentation. The IRIS Explorer documentation set has been completely overhauled and enhanced for this release. A new layout has been adopted, which gives greater consistency between the on-line and hardcopy form of the documentation.
   • The HTML pages now link to a stylesheet which can be modified for each installation to change the appearance (font families, font sizes, colors, borders, etc) of all of the documentation. The stylesheet (in which, by default, all of its options are commented out) is at %EXPLORERHOME%\docs\html\style.css (Windows) / ${EXPLORERHOME}/docs/html/style.css (UNIX).
   • Bug fixes and other system enhancements.
3. What is the history of IRIS Explorer? [Top]
   
   IRIS Explorer was originally developed and distributed by Silicon Graphics, Inc. (SGI). Interest in the system grew over the years and SGI decided to move IRIS Explorer to an external independent software house. On 25th July 1994 the Numerical Algorithms Group (NAG) took over the development, porting, marketing, sales and support of Silicon Graphics' IRIS Explorer data visualisation and application builder software.
4. What platforms does IRIS Explorer run on? [Top]
   
   IRIS Explorer is currently supported on the following platforms (platform / OS / Version):
   
   
   • Apple Power Mac OS X
   • DEC Alpha Digital UNIX [HP / Compaq Tru64 UNIX] (V4.0F)
   • Hewlett Packard PA-RISC 2.0 HP-UX (10.20, 11.00)
   • IBM RISC System/6000 AIX (4.3)
   • PC Intel Linux (RedHat 6 or compatible distributions)
   • PC Intel Linux (RedHat 8 or compatible distributions)
   • PC Intel Itanium Linux 64-bit (RedHat 7.1 or compatible distributions)
   • PC Intel Windows (NT 4 / 2000 / XP)
   • Silicon Graphics IRIX (6.2, 6.5)
   • Sun SPARC Solaris (2.6, 8)
   Development and enhancement of IRIS Explorer continues all the time so if you do not see your machine listed please check here or contact your nearest IRIS Explorer Centre for further information.
5. What are the hardware and software requirements? [Top]
   
   The hardware and software requirements can be found in the Installer's Note for the relevant platform:
   
   
   • Release 5.0 Installer's Notes
   • Release 5.2 Installer's Notes
6. What factors affect the performance of IRIS Explorer on my system? [Top]
   
   As with any large program, the processor speed and the amount of available memory are critical factors affecting the performance of the application. Other factors that influence the performance of IRIS Explorer include:
   
   
   • Graphics accelerator speed (compliance with the OpenGL standard is key)
   • Volume of data being stored
   • Map complexity and whether the map is distributed
   • Whether IRIS Explorer is installed locally or running across a network.
7. What standards have been used to develop IRIS Explorer? [Top]
   
   IRIS Explorer utilises the Open Inventor, ImageVision and OpenGL libraries. Users need not, in general, be aware of these lower layers unless they wish to create modules that call these libraries directly (i.e. not through the IRIS Explorer API supplied). In these cases, the user will need to acquire appropriate versions of the required library for their host platform. For further information please contact your nearest IRIS Explorer Centre.
   
   In the development of IRIS Explorer, NAG has used a variety of GL products supplied by both hardware vendors and software suppliers. The developers always seek to select the underlying Open Inventor and OpenGL system(s) that provide the optimum performance to the end user on as wide a range of graphics cards as possible.
8. How can I evaluate / order IRIS Explorer? [Top]
   
   Please contact your nearest IRIS Explorer Centre.

The IRIS Explorer Environment - Answers

1. How can I get started with IRIS Explorer? [Top]
   
   You can find the Introductory Tutorial Guide for NT here and for UNIX here.
2. How can I get my data into IRIS Explorer? [Top]
   
   There are a number of ways of getting your data into IRIS Explorer. These are (in order of complexity):
   
   
   1. If your data format is already supported by IRIS Explorer then all that is required is to simply open the relevant module, choose your file and connect the output into your map.
   2. If this is not the case, but you are trying to read a standard format (netCDF for example), then it is worth looking on the web to see if there is a public domain module that does the job. (see below for WWW references).
   3. There also exist readers for standard file types (like unformatted binary and ASCII text) in the public domain. For further information please contact your nearest IRIS Explorer Centre.
   4. A tool called QuickLat (see below) is available for all supported platforms.
   5. For the UNIX platforms, there is a tool called DataScribe (see below).
   6. A module can be developed to read your format. This work could be undertaken by yourself, by someone in your organisation or by the NAG Consultancy Service (For further information please contact your nearest IRIS Explorer Centre).
3. What is QuickLat? [Top]
   
   QuickLat is a new tool in IRIS Explorer 5.0 that provides a simplified interface for building data reader modules. Working with QuickLat, the user specifies the form of the output lattice datatype together with other parameters such as input filenames. QuickLat then automatically generates template code in either C or Fortran which contains simplified hooks into the lattice data and coordinate arrays, and the user adds the code to read into these arrays, given the format of their input file. The last step is to compile and use the module to read the data into an IRIS Explorer map.
4. What is the DataScribe? [Top]
   
   The DataScribe is a graphical utility to allow the user to build templates which can convert data between formats - this is typically used to convert a customised user data file into, for example, a lattice and vice versa. These data conversion templates, when completed, constitute modules in IRIS Explorer that can be used in the same fashion as any other module.
   
   Please note: DataScribe is currently only available on the Unix platforms.
5. Where can I find public domain modules? [Top]
   
   For resources on the Internet, see below.
6. What is the Map Editor/Librarian? [Top]
   
   The Map Editor and Librarian are the two main windows that are used when you use IRIS Explorer.
   
   The Map Editor is a graphical tool for assembling the maps by picking modules and joining them together in an intuitive manner. The editor will only allow the connection of input/output port pairs of the same data type, so IRIS Explorer is a 'strongly typed system'. The Map Editor is effectively the interactive prototyping environment of IRIS Explorer.
   
   The Librarian is the tool that allows you to browse through existing modules and maps, to choose those that you wish to use with the map editor.
7. Modules, maps and ports - what are they? [Top]
   
   A module is a single software tool for performing a particular task. IRIS Explorer is shipped along with a wide range of modules to perform tasks such as data input, rendering, image processing and manipulation. Each module has associated input and output ports that control the flow of data in and out of the module.
   
   Modules are connected together to form pipelines which perform specific higher level tasks. The collection of such modules and the links between them are referred to as IRIS Explorer maps. The function of the map is implicitly defined by the functions of the modules and their interconnectivity.
8. What are the data types in IRIS Explorer? [Top]
   
   There are five standard, platform-independent data types in IRIS Explorer, namely:
   
   
   • Parameter: A scalar value. Used to control the behaviour of module
   • Lattice: A generalised, multi-dimensional array having data and coordinates. Used to store point - based values.
   • Pyramid: A hierarchy of lattices, with information on how they are connected. Used to store element (vertex, edge, face, volume...) - based values.
   • Geometry: An Open Inventor scene graph (collection of geometric primitives).
   • Pick: A set of information about part of a scene displayed by a module.
   
   It is possible to add customised data types, although these will not be compatible with the standard module set. Customised data types will not be platform-independent, unless the user adds XDR-like data conversion.
9. What is the Module Builder? [Top]
   
   The Module Builder is a graphical utility to aid in the creation of IRIS Explorer modules, by helping you define which data types the module has on its input and output ports, which widgets correspond to which parameters, and how the module will look when placed in the Map Editor. It also generates any required wrappers around the core function.
   
   
10. Can I run modules on different machines? [Top]
    
    Modules within an IRIS Explorer map can execute on different machines, provided that those machines have IRIS Explorer installed. For example, in a network of 5 workstations (e.g. SGI, Sun and IBM) each of the 5 modules of an IRIS Explorer map can be running on a different workstation.
    
    This is achieved by opening a Librarian window for each of the machines on which you wish to execute modules. The Librarian for these machines will show which modules are available, and these can be placed in a map in the same manner in which local modules are placed. Everything will `look' the same, except that the remote modules will fire and execute on the remote machines - this could be referred to as a form of coarse grain parallelism.
    
    
11. How can I create a module without writing C or Fortran? [Top]
    
    IRIS Explorer has a built in module prototyping language called SHAPE. It is an array-oriented language that is executed (interpreted) by a module called "LatFunction". For further information, please refer to the IRIS Explorer documentation.
12. What options exist when starting IRIS Explorer? [Top]
    
    IRIS Explorer can be run in different modes depending on the requirement of the user. To run Explorer and automatically load an existing map into the Map Editor, start IRIS Explorer using the "-map" option (e.g. explorer -map <mapname>).
    
    It is also possible to run IRIS Explorer in "run time" mode, i.e. displaying just your developed application, not the Librarian or Map Editor. To do this, use the "-app" option (e.g. explorer -app <mapname>).

Further Information - Answers

1. Where can I obtain further information or support? [Top]
   
   Please contact your nearest IRIS Explorer Centre.
2. Where can I find IRIS Explorer information on the Web? [Top]
   
   NAG's IRIS Explorer web pages contain a wealth of information, including documentation, installer's and release notes, FAQs, user stories and technical reports.
   
   The module repository at the University of Leeds IRIS Explorer Centre of Excellence is an excellent source of modules.
3. Where can I find IRIS Explorer documentation? [Top]
   
   If you have IRIS Explorer installed on your machine, the documentation is in HTML format in the "docs" sub-directory of the distribution. If you have not (or it was not installed) you can also find the documentation on the NAG web site.