A Critique of the Proposed National Education Policy Reform
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Enhancing Parallel Coordinates with Curves
1. Using Curves to Enhance Parallel
Coordinate Visualisations
⢠Martin Graham & Jessie Kennedy
⢠Napier University, Edinburgh
2. Overview
⢠Background
⢠Using Curves
⢠Spreading and Focus+Context
⢠Conclusions
⢠Future Work
3. Background
⢠Parallel Coordinates visualise multi-
dimensional data across a set of parallel
axes â 1 axis per data dimension
(Inselberg & Dimsdale, 1990)
⢠Objects represented as poly-lines across the axes,
intersecting the axes at the appropriate value
X Y Z R
1 1 1 1 (X, Y, Z, R)
2 2 2 2
(1.5, 2, 3, 3.2)
3 3 3 3
4 4 4 4
5 5 5 5
4. Background
⢠Various refinements made to the basic
technique by IV researchers
⢠General Interactivity
⢠Selecting, filtering, re-arranging axes
⢠Angular Brushing â Hauser et al
⢠Pick out polylines with segments of certain Ѳ â
helps identify trends between attributes
⢠Hierarchical clustering - Fua et al
⢠Stats-based distortions â G. & N. Andrienko
5. Background
⢠Exploring Parallel Coordinates as a
technique to visualise and filter individual
and company CV data
⢠Quantitative data - salary
⢠Categorical data
⢠Ordinal â qualification i.e. Masters > Bachelors
⢠Nominal â sector i.e. Legal, IT, Engineering
8. Using Curves
Can act in conjunction with colouring and brushing
9. Using Curves
⢠Curved paths tend to resolve individually
⢠Gives better picture of dataset population
⢠Bad for screen clutter with many curves
10. Using Curves
⢠We can use curves because in our data
sets the lines act as connectors only
⢠In Inselbergâs original work, the intersections
of polylines between axes carried information
about the higher order object they formed
⢠But with heterogeneous dimensions, the
positions of inter-axial line crossings donât
mean anything
11. Spreading & focus+context
⢠Curves can help differentiate objects that
share an attribute value, especially if they
are dissimilar in other values
⢠But for categorical data especially, paths can
form a number of dense knots
⢠Can we use screen space more effectively to
spread these paths out over a distance?
14. Spreading & focus+context
⢠Bounding boxes around categories keep
objects visually grouped
⢠A curveâs position of intersection in the
bounding box is decided by averaging its
vertical coordinates in adjacent axes
⢠Impact can be increased if selected
values are expanded â i.e. focus+context
15. Initial User Testing
⢠Simple observation of six representative
users using system
⢠Users could track curves across axes for
small sets, especially outliers
⢠Users questioned need to draw all objects
as curves
⢠Users mostly liked parallel coordinates as
a whole
16. Conclusions
⢠Developed techniques that enable objects
to be followed through âcrossing-pointsâ in
parallel coordinate visualisations
⢠Techniques work best when
⢠âŚtracking outliers â often the interesting objects
⢠âŚused on small sets of user selected objects
⢠âŚused in conjunction with brushing techniques
that use colour
17. Future work
⢠Investigate situations when it is best to
use curved representations
⢠Curved paths for brushed and/or selected
items only to reduce screen clutter?
⢠Further investigation of focus+context
effect
⢠Link the focus effect across axes so selected
items get more space on every axis, not just
in the axis of selection
18. Future work
⢠General issues
⢠Implementing undo functions for selections
⢠What if one individual fits multiple values on
an axis?
⢠Further User Testing