A POLYLINE-BASED VISUALIZATION TECHNIQUE FOR TAGGED TIME-VARYING DATA - Information Visualisation: Techniques, Usability and Evaluation - page 168

Fig. 9.3. Representative polyline selection.
The technique provides a click and sketch interface, so users can
specify interesting representatives by clicking directly or sketching
particular shapes. When a user clicks a point on the display, the technique
calculates distances between the point and all segments of the drawn
polylines. If at least one of the segments of a polyline is close enough to
the clicked point, the technique highlights the current polyline. When a
user draws a curve on the display, as shown in Fig. 9.4, the technique
samples several points on the curve, and calculates distances between the
sampled points and all segments of the drawn polylines. If at least one of
the segments of a polyline is near enough to each of the sampled points,
the technique highlights the current polyline.
While polyline reduction in our technique improves readability of the
data, users may want to look at all the polylines that have features of
interest. To satisfy such requirements, the technique can reactivate the
non-representative polylines, which belong to the clusters of the
representative polylines specified by click/sketch operations. Users can
specify particular tags to be extracted by the above query operations. It can
highlight only the parts of the polylines corresponding to the specified tags
during click or sketch operations. Also, it can reactivate only the parts of
the non-representative polylines corresponding to the specified tags.