Creating And Manipulating N-Dimensional Brushes
Matthew O. Ward
Techniques for interactive brushing, as found in multivariate
data visualization systems, can be categorized as either screen-space
or data-space. Screen-space techniques consider a brush to be
a 2-dimensional shape (usually a rectangle) which can be used
to select points which map to a particular region of the display.
Data-space techniques assume the brush has as many dimensions
as the data set, i.e. the brush specifies an N-dimensional subspace
of the entire data space. In this paper, I describe methods for
specifying and manipulating N-dimensional brushes and show their
implementation in the public domain visualization package XmdvTool.
Among the topics covered are user-driven versus data-driven brushing,
direct and indirect brush specification and modification, management
of multiple simultaneous brushes, composite brush creation, and
with ramped boundaries.