A configurable visualization environment

Abstract

The different steps in developing a simulation program, as well as the multiple application domains, imply many expectations from visualization and the visualization environment greatly influences the perception of the information contained in the solution. The methodology presented is centered around the concept of configurability, i.e. the possibility for a user to specialize the visualizator for current needs and therefore create a working environment tailored for specific domains and situations. Configurability allows for the sharing of generic elements and algorithms of visualization, and also for a natural environment of communication. It provides functions for a linear thinking context (repetitive creation of same representations, systematic use of a set of images for comparison or validation), but also for exploration of the characteristics of the solution. This communication uses the paradigm and the syntagm of a language, the language of visualization. This work presents the results of an analysis of visualization from the point of view of linguistics. The goal is not to present new methods for displaying results, but it is rather an attempt to define its structure. We present visualization as an activity of communication of information. Visualization Environments Historically, in the visualization world, applications have generally preceded the structuration of ideas. Existing visualizators individually present new concepts and ideas, but without integrating them into a structured approach appropriate to a model of visualization. Early visualization tools were iri-house efforts carried out at the level of specific routines, custom made for a given problem, and written by the end°Copyright ©1995 by Ozell and Camarero. Published by the American Institute of Aeronautics and Astronautics, Inc. with permission. user himself. These evidently lacked generality, both from the functionality and the portability perspectives. The first step to improve this, was to isolate the display functions. Hidden line removal, shading, interactive manipulations were given to a graphic language or even to specialized hardware. It was then possible to support a greater variety of equipment and to orient their development to conform with the emerging standards. The next step was to apply the same standardization to the dialogue functions using commercial libraries like OSF/Motif. The result is a modularization of the visualization process with the emergence of a well-defined core, consisting in data extraction and virtual image creation (Fig. 1). This evolution has been characterized by a shift from a situation where the end-user is also the author, to one where the development is carried out by professional computer scientists. The next phase in this evolutionary process, is the ability to service the diversity of needs ranging from debugging a grid generation or a simulation program, to the production phase of a project. This requires a configurable software package that allows to share the most generic elements of visualization: dialogue, graphics, basic extraction algorithms. Configurable is not to be confused with programmable. It is rather the ability to assemble, from a given tool set a combination of functions within a visual and communication environment, i.e. a non-programming environment. The current visualization environments can be grouped in three categories with varying flexibility. Programs [1, 2] offer a turnkey architecture with a fixed functionality that the user cannot modify. Libraries [3, 4] lend themselves to a better flexibility providing access to visualization functions, but require programming knowledge. The interaction with the end-user is then the responsibility of the programmer. Visual programming environments [5, 6, 7, 8, 9] based on data flow diagrams are more recent. They are excellent for prototyping, but not u s E R Extraction + calculations