9.2 Application Visualization System (AVS)

9.2.2 Comments

Range of versions: Strength

• Increasing Competition: AVS has the advantage of having been in use on commonly available platforms for several releases and as such is a mature product
• Increasing Population size: AVS is likely to support hardware platforms available to the new user
• Moving to the Desktop: AVS is available on a wide range of platforms, including typical desktop machines, such as colour Suns, SG Indigos, HPs, DECs and PCs (next year) and has been tailored to take advantage of special hardware features and local graphics libraries

Company stability: Strength

• Increasing Competition: Although AVS are reliant on just two products (i.e. AVS and UNIRAS) they appear to have a strong position in the general visualization market. They were the first to market such a product and have held on to their early customers. Their proven track-record continues to attract new customers from a wide range of application areas. The development team grows every year and is now in the 20s, with the company apparently committed to vigorous and continuing improvement of their software.
  
  AVS/UNIRAS Ltd., is the UK subsidiary of Advanced Visual Systems Inc. and currently has eight full time employees with an expected increase in 1995.

Costs: Strength

• Static Purchasing Power: A CHEST deal (2.5 years remaining) is available whereby a single fixed charge each year allows academic sites unlimited use of the base software on a wide range of platforms. The current CHEST deal does not include the Chemistry or UCD viewers but example networks are provided. It is also possible if there is enough interest in a particular add-on that it can be added to the CHEST deal, e.g. the Animator is obtained at an additional but reasonable cost.
• Increasing Population Size: The CHEST deal makes AVS attractive to a growing population
• Move to the Desktop: With the CHEST deal no further costs are involved in moving to a desktop system. It is not necessary to buy additional licences or new versions as common desktop platforms are included in the site-wide deal.

Data input tools: Strength

• Widening Skill Range / Rising Expectations: AVS has an interactive facility, the AVS Data Interchange Application (ADIA), to import data into AVS fields. To access this use the field descriptor module from the network editor. Having saved the data format as a template it is then possible to re-use this for other datafiles with the data dictionary module. These tools only allows the user to import field data and not polygonal or UCD (e.g. Finite element) data, so it may prove limiting in view of users' rising expectations. It can cause problems to novice users too that may need to specify offsets in the data file by number of bytes (a graphical interface where the user can select with the mouse where new data starts would be easier to use).
• Increasing Competition: Although the data input tool will not handle all data and may cause problems for novice users, it is considered an asset to have an interactive tool to import data.

Data readers: Strength

• Increasing Competition: AVS have a large number of data readers, both in the public domain and from commercial sources (e.g. AVS, Tessella)
• Increasing Population size: With the large amount of example code available, developing a new reader can be a relatively easy task for a new user.
• Increasing Use: As the user uses AVS for more data visualization, there is a good chance that a data reader will already be available for the new tasks.

Video capability: Strength

• Increasing Competition / Rising Expectations: There are a number of ways to create animation and video with AVS. For simple animations modules such as animated integer can step through a range of values, which can be used to change parameters. For more complicated animations the Animator tool is of great benefit, and can be used to control changes in parameters, data input, camera positions and even networks. The Animator is a key-frame animator, and has 2 levels of control panels, one for newer users or less complicated animations, the other for advanced use. The simpler panel shows a small subset of fairly simple functionality, such as add/delete keyframes and play. The full panel gives greater control over the time between each keyframe. Although the Animator is probably beyond absolute novices, slightly more experienced users will find this of great benefit.
  
  In addition it is possible to generate an MPEG movie from an animation (i.e. sequence of images) using a public domain module from the International AVS Centre (IAC). This module can be found in avs modules/data output/Create MPEG, but note this does not generate MPEG directly but calls the standard mpeg encoder.
• Problem size increasing: The ability to create quality animations stored to video is an advantage in the case of increasing problem sizes since it is not always possible to view the visualization in real time
• Increasing Bandwidth: Increased bandwidths will make the strong animation facilities even more attractive

Hardcopy: Strength

• Increasing Competition / Rising Expectations: Support for PostScript for hardcopy output is good. It is also possible to convert an image to CGM. The expected addition of UNIRAS functionality in AVS6 will improve hardcopy support to cover many more devices and formats. Advanced facilities are available, for example, views which have a mixture of shaded rendering and line drawing can be saved as a mixture of lines and image in PostScript so as to make best use of hardcopy devices.

Documentation: Strength

• Widening Skill Range / Increasing Use: The documentation can prove difficult for novice users (e.g. no Getting Started guide) and as a reference source can be missing necessary information. However it is readable and for many users it is possible to find the required information and so on balance the documentation is considered a strength.
• Move to the Desktop: The user will probably have to purchase a paper copy of all of the documentation as it seems unlikely they could manage with the small amount of on-line information available
  
  The next version of AVS (AVS6) though will have online, context-sensitive, hypertext help system based on the Bristol Hyperhelp for Unix and Winhelp for Windows.

Support: Strength

• Static Purchasing Power: The support of AVS is included in the CHEST licence arrangements
• Increasing Competition: AVS currently provides good technical support in the UK and access to the larger support team in the US when necessary.
• Increasing Population Size and Use / Rising Expectations: Could overstretch the resources of the support team.

Usability: Weakness

• Widening Skill Range: Novices often find the system difficult to use, for example, where several modules appear to do the same thing, such as isosurface and ucd iso. In the next release of AVS, 6.0, expected next year, an object oriented approach and improved general data types means a single isosurface module will be available.
• Increasing Use: Poor usability becomes less noticeable once the user understands which modules to choose and why.
• Rising Expectations: Apart from the many example visualizations available in the form of networks, some of which are packaged into a menu-driven viewer (dataviewer), it is also possible to purchase customised data viewers (e.g. for UCD, and chemistry). Therefore it may be possible to visualize new data without the development of new code.

Functionality: Strength

• Static Purchasing Power: With strong functionality the need for alternative systems is reduced
• Increasing Competition: A large number of modules are available in the Public Domain (IAC) and within AVS itself.
• Rising Expectations/Increasing population size: As the users' expectations rise there is a good chance with the large number of modules available that they can find what they need

Distributed support: Strength

• Static Purchasing Power: AVS has good support for distributing modules across a number of platforms to share the workload for an application, allowing the user to make better use of the available resources
• Increasing Competition: The ability to distribute modules is considered an asset.
• Problem size increasing: As the problem size increases it is possible to distribute the task across a number of platforms, either by taking advantage of larger, more powerful machines or splitting the task so each part can be processed separately.
• Move to the Desktop: When a user moves to a desktop system they can take advantage of the distributed support in AVS to farm out difficult and large problems.
• Increasing Bandwidth: With increased bandwidth the transfer of data will improve. Since distributing applications often involves transferring data from one system to another greater benefits in speed can be expected from distributing large, complex problems.

Customisability: Strength

• Widening Skill Range: A user with relatively little experience can expect to be able to customise AVS. With a small amount of experience users can produce an application to process simple data. The user interface can be modified to some extent without any programming (e.g. by using the mouse the user can switch between typed in values and dials or sliders). For more experienced users it becomes possible to add new tools. For advanced users with access to the developers' kit it is possible to tailor all AVS modules or produce an application that just uses the required parts of AVS (e.g. a scaled-down geometry viewer). This will become easier with the next developers' kit (Express) which is the underlying system for AVS6.
• Increasing Competition/Increasing Use: The ability to customise applications to end-users' needs is of great benefit. With AVS6 there will be even more control for the expert, including the ability to modify Motif-type interfaces too.
• New Algorithms: Since AVS can be customised it is possible for new algorithms to be incorporated as modules into AVS. There is also a large amount of example source code in the public domain (e.g. IAC) which may be tailored to include new algorithms.

Command language: Strength

• Widening Skill Range: Although not considered suitable for novices the command language, CLI, is extremely useful for scripting applications and demonstrations. Less experienced users can rely on AVS itself to record scripts, which can then be tailored. CLI scripts can be used to build and change networks as well as to change parameters. It is possible to journal a sequence of events by starting AVS with the -cli option and opening a script for saving events with script -open file - this does not record all events (e.g. geometry animations) but they can be added in afterwards by hand. It is also possible to develop modules that call CLI commands so networks can change to handle different events/data.
  
  V, the replacement for CLI in AVS6, will have even more powerful commands and should be easy to master for those already familiar with Unix shell scripts.
• Rising expectations: For the reasons above (in Widening Skill Range) CLI can be a powerful facility. In AVS6 the command language will be even more powerful with programming type control and expression evaluation.
• Problem size increasing: With increasing problem sizes it is often useful to be able to produce a batch of commands which can be left unattended to produce a visualization (although this does require the use of a graphics screen for display).

9.2.3 Summary

• importing data
• processing and filtering data
• mapping data onto geometric primitives or an image representation.
• rendering the geometry or images

The maturity of the AVS product is one of its strengths. The first version of AVS (AVS1) was released in April 1989 and it is now currently in its fifth version (AVS5). The new development environment AVS/Express was released during 1994 and the summer of 1995 will see AVS6 which will be based upon the new architecture of AVS/Express bringing many new improvements.

There is also a very good infrastructure in place for the AVS system in the public domain with the International AVS Center's activities in the US collecting and porting user contributed modules.

One of the disadvantages, as with most of the application builders, is the complexity of the system for the first time user. This leads to an initial steep learning curve which can be an obstacle for novices. Improvements in on-line help and tutorial facilities would alleviate this and the releases of AVS6 may address these.