Visualization Options
There is a dialogue window in our software that
contains the controls for setting the type of transparency
and its distribution (Fig. 5). Each fixation adds a certain
amount of transparency in each point of visualization.
However, only the Gaussian distribution covers all the
display, whereas the other distribution types affect only the
area in the vicinity of the fixation. The shapes of influence
for all the distributions available are shown in Fig. 6. In
this figure, the x axis denotes distance from a fixation, and
the y axis denotes influence on the transparency.
The controls of the second group (Transparency
creation) allow adjusting the influence of each fixation on
the transparency. Sensitivity (S) denotes the radius of
influence (Linear and Linear + Sine distributions), or
variance σ2
(Gaussian distribution).
Brightness level (BL) is used as the gain for the
distribution functions. It shows the minimum fixation
duration (FDi) that makes the view totally transparent at
the place of its occurrence.
Hiding level (HL) denotes the initial level of the
shadow’s or fog’s opaqueness. Totally hidden background
of the view corresponds to HL of 100%.
The meaning of the last control (Slicing level)
depends on the value of the option Slicing. By default, it is
None, which means that transparency just changes by one
of the distribution rules and no slicing is applied (Fig. 7a).
With the option Steps checked, transparency is
shaped like terrain steps (Fig. 7b). The width of each step
equals the value of Step level in pixels. The transparency
rate of a step is the average of all pixels in the step.
With the option Mask checked, transparency lower
than the value of Mask level is not applied to the
visualization (Fig. 7c).
Finally, with the option Relief checked, the
calculated transparency is applied only if its value is a
multiple of Relief level. This makes visualization similar to
the topographic map (Fig. 7d).