bradshaw@qucis.queensu.CA (Tom Bradshaw) (11/10/89)
The following is a note I am forwarding for a friend. Please reply to
GALLERC%ALCANKTN.bitnet@ugw.utcs.utoronto.ca . They are looking for
Visualization tools for machines like the SPARC station.
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The following is a description of the functions we are searching for in a
"Scientific Visualization" tool.
Primarily we wish to be able to take scientific data generated by, for
example, a finite element analysis program and allow the user to interact
with it. (i.e. the data could be regular or irregular gridded nodes.) The
display would consist of polygonal data and the user would be able to
orient a cutting plane through objects. The area outside of the cutting
plane can be rendered in wire frame but where alpha blending is available
we would prefer that the area be optionally displayed as transparent or
semi-transparent. The data will have additional scalar information
associated with it such as stress, temperature, turbulence or field
intensity inside the object. This scalar data should be representable by
different colours.
It should be possible to animate both the object itself as well as
displacements and the scalar values at each node in real time. (i.e. time
steps of data will be pre-computed and the visualization tool would be
asked to interpolate between these.)
One feature we are very interested in in the capability to interactively
select and display iso-contour surfaces. An iso-contour surface is a
surface inside the data where all of the stresses or field strengths are
the same. Some examples are attached (Figures 1 & 2).
Other features such as ability to display more than one model (object) at a
time (for comparison purposes), legends for stress (colour) values, titles
and notes, as well as hardcopy capability for interactively selected views.
It would be useful to be able to set the cutting plane at a precise
location in the object in order to examine specific 2D planes in isolation
(Figure 4).
Another area of interest is the visualization of flow fields (vector data).
Here animated particle as well as front movement is required. Changing the
vector's colour, width, etc., depending on other scalar properties at that
point, should be possible.
Description of Attached Figures:
The figures were produced on a Tektronics 4693A thermal wax printer. They
are representative of the type of thing we have in mind but are not as
"pleasing" as the original workstation version, particularly with respect
to the appearence of the transparent regions.
Figure 1.
Here we show 2 models (2 graphical objects slightly displaced) whose
outer surfaces have been rendered in wire frame but inner surfaces
(electric field values) are shown as 3D iso-contour lines. The cutting
plane is visible but not in use (offset from data). The user is able to
interactively and in real time select which inner surface is being
displayed.
Figure 2.
Same data set as in figure 1. Here the cutting plane is in use.
Object parts behind the plane are rendered as a shaded silver material,
with the cut plane showing scalar colour values. In front of the cutting
plane the objects are wire frame and translucent iso-contour surfaces are
displayed.
Figure 3.
Same as figure 2 except that in the upper object transparency rather
than wire frame is used in front of the cutting plane. In the lower object
the parts behind the cutting plane are rendered to show the scalar values
at the exposed surfaces. In both objects the iso-contour surfaces are
shown in front of the cutting plane.
Figure 4.
2D image of a single plane of interest, in this case a slice near the
bottom of the lower object seen in figures 1,2 & 3.