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NAG's Graphics and Visualization Products


NAG launched its first graphics product in 1982, the NAG Graphical Supplement, Mark 1. Over the past year NAG has acquired the development and exploitation rights of IRIS Explorer and has made a distribution agreement with Template Graphics Systems (TGS) for its range of graphical software. So where does this leave NAG's graphics and visualization offerings? What is the current relationship between the products and where can NAG's graphical offerings go in the future?

NAG Graphics

The NAG Graphical Supplement, Mark 1, was a Fortran callable library that had to be used in association with the NAG Fortran Library and which provided routines for basic graphical functions (eg axes) and graphing results from numerical calculations. The library was interfaced (via a defined API) to several underlying graphics systems such as GINO, GHOST, DEC ReGis and GKS.

The NAG Graphical Supplement became the NAG Graphics Library (independent of the NAG Fortran Library) and is now at Mark 4 with no further development currently planned. The NAG Graphics Library has been successful despite the fact that it is a Fortran, multi-call, non-interactive graphics library. This is probably due to its close coupling with a numerical library capability and its strong underlying algorithms (which derive directly from the NAG Fortran Library software) and of course reflects the fact that there continues to be a substantial community who enjoy the flexibility of incorporating graphics calls directly within their Fortran simulation code. NAG distributes (outside North America and Japan) the Template Graphics range of software including:

TGS are also working with Silicon Graphics on the WebSpace viewers for VRML, the Virtual Reality Modelling Language, which provides the 3-D extension to the World-Wide Web.

IRIS Explorer

IRIS Explorer is a scientific visualization system using a dataflow model for operation and a drag-and-drop user interface. It provides an extensive range of capabilities for reading, manipulating, sectioning and visualizing complex data. However, IRIS Explorer is more than just a scientific data visualization system, it is a comprehensive application building system and prototyping framework. IRIS Explorer is now developed and maintained within the UK directly by NAG.

IRIS Explorer has no intrinsic visualization capability, indeed, the central framework only provides the capabilities of encapsulating user code in modules, interconnecting modules into maps and controlling the execution of those maps, potentially over a distributed, heterogeneous network of machines. Note that the user code to be encapsulated in a module can be in Fortran, C or C++ and access to the source is not required.

The functionality of IRIS Explorer, as seen by the user, is provided by the range of pre-built modules provided with the system. At present, the only large-scale module suite available is targetted at data visualization, hence IRIS Explorer's position in the software market. However, it is possible to provide any other functionality within the IRIS Explorer framework through defining new data structures (for which support is provided) and associated modules. IRIS Explorer maps can also be collapsed into a single interface application for delivery to end users.

The IRIS Explorer visualization capabilities are built on top of the Open Inventor geometry capabilities with rendering taking place via OpenGL. There are many advantages to this, not least compatibility with VRML through Open Inventor and the emerging range of convertors to the VRML (and hence Open Inventor) format. Also, IRIS Explorer can exploit the rich functionality of the Open Inventor / Open GL software - stereo facilities for example.

The NAG Graphics and Visualization Portfolio

At first sight it may appear that NAG's portfolio of graphics and visualization software is functionally rich but not wholly coherent. However, there is a strong inter-relationship between the software systems offered and good migration paths for current and future users.

For NAG's existing customers there is now a migration path from NAG Graphics to the higher level and easier to use two-call graphics libraries from TGS. The TGS products also provide support to C users and users wishing to add some interaction to their programs or for whom the post-production editing capabilities of FIGraph would be an advantage.

For users working at the two-call graphics level, NAG can offer the higher level of abstraction provided by IRIS Explorer, where the users' functional code can be embedded in one or more modules and the visualization facilities are provided by IRIS Explorer. This approach allows greater flexibility for less coding effort while still allowing the user access to existing codes and libraries.

For graphical programmers, the same staged approach can be adopted. Programmers working at the lower level of OpenGL programming may find that moving to Open Inventor will greatly simplify their work, and Open Inventor development can take place within IRIS Explorer. For this progression there is a clear line of compatibility, Open Inventor is built on top of OpenGL and IRIS Explorer uses Open Inventor. This hierarchy also allows the IRIS Explorer developer to use increasing levels of sophistication if required, expanding from use of the IRIS Explorer geometry API to full Open Inventor and on to OpenGL.

So, by offering a range of capabilities from low level numerically oriented libraries up through interactive visualization software and on to general purpose 3-D graphical facilities NAG is aiming to support users as their own needs vary.

NAG's Other Products and Future Directions

Of course, graphics and visualization are not always an end in themselves. In most application areas the generation or analysis of the data is the key to the success of the system. NAG is, of course, a supplier of mathematical software for numerical processing (Fortran, C and other libraries), statistical processing (Genstat and Glim), computational algebra (AXIOM) and related requirements. The main advantage of this for the user is that there is a single point of contact for many of the elements that they require. If the user needs to use several techniques in a single application then they come from the same place, with the advantages of co-located developers and if the user experiences difficulties integrating the parts they need, there is only one port of call for help, not several. The graphics and visualization portfolio described above has only just come together, but already NAG is seeking to integrate the technologies with its other products. The first fruits of this work appeared in IRIS Explorer Release 3 which included both NAG Graphics software (for 2-D graphs) and improved numerical operation in some modules thanks to NAG's numerical capabilities. Work is also underway on putting Open Inventor into AXIOM and looking at providing broad statistics capabilities within IRIS Explorer.


NAG has enhanced its range of graphical and visualization product offerings to offer a number of capabilities, at different levels, to meet a variety of user requirements. By providing a set of related products, and by increasingly integrating the capabilities of each product, NAG is seeking to offer an unparalleled range of facilities to the professional user.

Robert Iles, NAG Ltd