Introduction

VIGIE¹ is an interactive visualization software of discrete data known in 1-D, 2-D and 3-D domains. Usually these data are produced by Computational Fluid Dynamic.

While many commercial and non-commercial softwares already exist for the same purposes, it has been found that to be used at their best, these softwares usually require visualization dedicated workstation with rather large CPU and RAM. Moreover, many visualization tools are general purpose visualization tools and contain many modules that are not of direct interest to the numerical analysist or the engineer. Consequently, the following ideas has been followed in the developpement of VIGIE:

• VIGIE uses an internal graphical library for simple visualisations. for more advanced rendering techniques an optional use of OpenGl is partially implemented. The entire VIGIE code is written in C and the only external libraries required are the XWindow Xlib and Motif libraries. This allows VIGIE to be used on several workstation types.

• VIGIE accepts general data formats. However, the internal data structure used in VIGIE (that is transparent to the user) is dedicated to scientific applications and does not contain features irrelevant for scientific computations. With respect to general purpose visualization software, this minimizes the memory required.

• VIGIE is a non-commercial software.

At the present time, VIGIE includes 1-D, 2-D and 3-D vizualisation modules on structured as well as non-structured (finite element type) meshes. VIGIE can handle very general types of meshes composed of hexahedra, tetrahedra, prisms or a mixing of those. A mesh can contain an arbitrary number of block, each block being structured or not. Actually, a limitation present in VIGIE is that we suppose that the values of the variables are stored at the mesh nodes. Therefore, the potential users of VIGIE that use datas where the variables are located at the centre of the elements or are constant by elements will have to interpolate their data before using VIGIE. The following modes can now be used in VIGIE:


1-D Modes : Displaying values with:

• Cartesian representation
• Multi² Cartesian representation
• Cartesian representation for RCS³
• Polar representation for RCS
• Multi Polar representation for RCS

2-D Modes : Theses modes allows to display scalar (isolines, color contours), vectors (streamlines, vector field), to scan a scalar along an arbitrary straight line, to probe a scalar in the mesh. All of theses features can be used in the two available modes:

• mono 2D plot.
• multi 2D plot.

3-D Modes : Five modes are available:

• multi 3D plot. This mode include features of the ``Plan Cut'' and ``Isosurfaces'' modes with common interactions with several solutions of the same problem.
• Plan Cut. Displaying of isolines and color contours on an cut plane of a 3D mesh.
• Flow. Displaying of streamlines and streamsurfaces.
• Isosurface. Computation of the mesh defining an isosurface for a scalar value, with interpolation of other scalar values on the nodes of this mesh, and visualisation.
• Volume Rendering.

All 3-D modes include interactive tools for 3-D positioning and quick display of the geometry and in general, possess animation features in order to extract more quickly the information from the data.

Most of actions which can be defined interactively, can also be defined by a simple langage in batch mode or in an ``extended description file'' for quick initialisation.