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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS, VOL. 12, NO. 5, SEPTEMBER/OCTOBER 2006 Multi-Scale Banking to 45
 

Summary: IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS, VOL. 12, NO. 5, SEPTEMBER/OCTOBER 2006
Multi-Scale Banking to 45
Jeffrey Heer and Maneesh Agrawala
Abstract--In his text Visualizing Data, William Cleveland demonstrates how the aspect ratio of a line chart can affect an analyst's
perception of trends in the data. Cleveland proposes an optimization technique for computing the aspect ratio such that the
average absolute orientation of line segments in the chart is equal to 45 degrees. This technique, called banking to 45, is
designed to maximize the discriminability of the orientations of the line segments in the chart. In this paper, we revisit this classic
result and describe two new extensions. First, we propose alternate optimization criteria designed to further improve the visual
perception of line segment orientations. Second, we develop multi-scale banking, a technique that combines spectral analysis
with banking to 45. Our technique automatically identifies trends at various frequency scales and then generates a banked chart
for each of these scales. We demonstrate the utility of our techniques in a range of visualization tools and analysis examples.
Index Terms--Information visualization, banking to 45 degrees, line charts, time-series, sparklines, graphical perception
Figure 1a. CO2 measurements, aspect ratio = 1.17. The x-axis shows
time, in monthly increments, while the y-axis shows carbon dioxide
measurements taken at the Mauna Loa observatory [2]. Note the bend in the
trend of increasing values, suggesting an accelerating increase.
Figure 1b. CO2 measurements, aspect ratio = 7.87. The wider aspect
ratio enables the viewer to see that the ascent of each yearly cycle is more
gradual than its decay. However, the bend in the lower-frequency trend is
now difficult to see. The choice of aspect ratios for Figures 1a and 1b were

  

Source: Agrawala, Maneesh - Department of Electrical Engineering and Computer Sciences, University of California at Berkeley
O'Brien, James F. - Department of Electrical Engineering and Computer Sciences, University of California at Berkeley

 

Collections: Computer Technologies and Information Sciences