1 Presented by Jean-Daniel Fekete

2  Motivation  Mélange [Elmqvist 2008] Multiple Focus Regions

3  Stack Zooming  Introduction  Stack zooming in detail  Layout and correlation graphics  Stack zooming in action  The TraXplorer System  System design  Visual interface  Video Demonstration  Summary  Future Work

4  Time-series data tends to be long and often its analysis requires comparison across multiple focus regions  Current time-series visualization tools have limited support for comparing several foci while retaining context  Stack zooming is a method for supporting this kind of multi-focus interaction in time-series data exploration  Based on building hierarchies of stacked 1D strips  Each subsequent stack represents a higher zoom level  Sibling strips represent branches in the visual exploration

5  Stack zooming is based on creating a stack of zoom areas  Nodes in a zoom stack are laid out on the visual substrate using a space-filling layout algorithm  Splits the vertical space by the depth of the zoom stack  Splits the horizontal space by the number of siblings at each level

6  Layout allocations can be changed by dragging the borders of a strip  The order of child strips for each level in the zoom stack is significant for conveying the positions of the displayed intervals of a time series  The layout manager will always order child strips for each level in the zoom stack to be the same as the order of their intervals on the parent strip

7  Relationships between parent and child strips in adjacent levels of zoom stack must be visible  Focus  Context  Distance awareness  We discuss three different correlation graphics that visually indicate the relationships between different visual strips in the zoom stack

8  Color-coded zoom areas:  Parent strips show color-coded semi-transparent selection areas  Indicates the position and extents of each child strip in the time series Color-coded strip frames: Child strips have color-coded frames that correspond to the color of its parent selection area This gives a visual link between parent and child

9  Color-coded zoom areas:  Parent strips show color-coded semi-transparent selection areas  Indicates the position and extents of each child strip in the time series  Color-coded strip frames:  Child strips have color-coded frames that correspond to the color of its parent selection area  This gives a visual link between parent and child

10  Correlation links:  Explicit correlation links drawn as dotted lines and arrows from zoom areas in parents to the children  Allows for quickly understanding the correlation structure  May be shown in a transient overlay to minimize visual clutter

11  When the user begins to analyze the dataset, the whole display is taken up by the full time series drawn as a line visualization on a single strip

12  Using a drag on the surface of this strip, the user can create a child strip of the main strip that displays the selected subset of the time data

13  Additional zoom operations on any of the dataset strips will create additional children in the zoom stack

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15  TraXplorer is designed to support a communication-minded iterative workflow  Exploration  Collaboration within the analysis team  Dissemination to external stakeholders

16  Components:  Main visualization window  Data box  Layer control box  Presentation tree window

17  The main visualization window is a visual space supporting stack zooming  Contains a visualizations of time- series data on a common time axis and potentially different value axes  Visualization type is independent of the layout management  Our implementation currently supports basic line graphs, filled line graphs, and horizon graphs

18  Each data series is a unique layer in TraXplorer  The layer control box can be used to move, to delete, and to toggle the visibility of individual tracks, as well as to change color mapping, transparency, and track title  Used to determine which track should be used for the value axis labels

19  Two or several tracks can be linked to use the same scale for the value (Y) axis, thereby supporting direct comparison of values 19

20  The data box displays local statistics about the currently selected region  Detail-on-demand for computing measures for a particular track  Min/max, average, median, standard deviation, etc  Add comments to any particular track  Checkboxes to add this data to the visual display of the track

21  The presentation tree is a hierarchical representation of the zoom stack  The analyst can prune, move, or hide individual zoom nodes (i.e. child strips) using the presentation tree to refine the presentation  Can access the exploration history using the presentation tree to linearize the combined exploration sessions of the data similar to a slideshow presentation suitable for presentation to the audience

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23  Theoretical background of a novel multi-focus interaction technique called stack zooming  Multiple focus points in time-series dataset visualizations  Context, distance, and relationships between time-series  The TraXplorer implementation  A visual interface to support the time series exploration  Supports stack zooming  Communication-minded workflow

24  Study the empirical performance of the tool in comparison to similar tools  Improve the tool to better support collaborative visual exploration settings involving teams of analysts working together  Study how the tool can help analysts fill different roles in the analysis process

25 Thanks! Contact information: Waqas Javed Contact information: Waqas Javed Merci JD!!!