Interacting with Huge Hierarchies: Beyond Cone Trees

Jeromy Carriere, Rick Kazman

Computer Graphics Lab, Department of Computer Science

University of Waterloo, Waterloo, Ontario, Canada N2L 3G1

{j2carrie,enkazman}@watcgl.uwaterloo.ca

System Lab 871786 高君豪

Introduction• This paper describes a system called fsviz which v

isualizes arbitrarily large hierarchies while retaining user control.– based on cone tree

• usage-based filtering

• animated zooming

• hand-coupled rotation

• fish-eye zooming

• coalescing of distant nodes

• texturing

• effective use of colour for depth cueing

• the applications of dynamic queries

Presentation

• They improve on the layout algorithms for cone trees.– Remove all visual clutter

– making better use of colour and node shape

– providing fish-eye viewing

Colour

• In the implementation presented here, colour conveys file size.– The greater the saturation of the colour, the larger the fi

le.

• They scheme maps ranges of file sizes to colours distribution is given to size ranges containing an equal number of files.

Shape

• Form initial prototyping with fsviz, we have observed that users can easily pick out files of different types when the nodes representing those files are different shapes.

• It should be noted that in the printed representation of the visulaization, it is difficult to distinguish node shapes.

Text

• This information is conveyed via text placed near the nodes in the tree.

• The text scales and rotates along with the tree such that it always faces the viewer.

Animation• The hand-coupled rotation, in which the user can d

irectly manipulate both their view of the cone tree structure and the orientation of the cone tree’s subcomponents.

• The software provides automatic animation in two ways.– The user can select a set of nodes in the tree and fsviz

will perform sequence of “zooms” to bring the user directly to that set.

– When a file is selected using the file information browser, the node representing that file will be rotated to the front of the tree.

Tree Layout

• A simple algorithm maydetermine the radii of the sub-cones within the tree based solely on the parent node in the tree.

– R(h) represents the radius of a tree at height h

– Ri is some fixed initial radius

– small trees

1)(

h

RhR i

Tree Layout

• It can effectively allocate space around the radii of the cones in the tree to accommodate the children.– all overlap between subtrees can be eliminated

• At all levels above, the circumference for a cone at level n-1 is estimated by:

– where ri,n is the radius of the child i ate level n

i

nin rC ,1 2

Tree Layout

• The radius is then calculated with:

• The arc length required for a child will be estimated by:

• Subtrees are placed around the cone, with angles defined by:

2n

n

Cr

ninii rrs ,,1

n

nini

n

ii r

rr

r

s ,,1

Fish-eye Viewing

• The basic mechanism depends on a Degree of Interest (DOI) function which defines the “importance” of a particular node in the structure.

– where x is the node being considered, y is the current focus, and root is the root node

),(),(|)( rootxdyxdyxDOI treetreetreefisheye

Automatic Subtree Coalescing

• The technique was applied in fsviz to reduce the number of nodes displayed at a given time.– A subtree is sufficiently distant from the user’s focus n

ode so as to be practically of no interest to them.• the subtree is collapsed

• the subtree is coalesced

• This representation is currently a tetrahedron, whose colour reflects the size of the directory itself.

Automatic Subtree Coalescing

• This technique serves two purposes:– it produces an improvement in rendering efficiency

– visual clutter is reduced