Visualization of Eye Gaze Data using Heat Maps
Usability testing is widely used today to determine, among other things, the quality of web site designs. To help the researchers, a number of techniques have been suggested for visualizing the eye tracker’s data. Using one of the most popular techniques, gaze fixations are plotted in 2-D against the stimulus image in the background. However, there is an alternative visualization technique, based on the heat map paradigm, which offers additional benefits by better separating the different levels of observation intensity. We present a modified version of this technique to facilitate visualizations by allowing the transparency of the heat map to depend on the gaze data itself. In our version, transparency is presented in either the gray scale, or employing some color scheme. The intensity is proportional to the duration of the observation. Thus, longer fixations add more transparency than shorter ones. Conversely, the least observed areas are hidden by a shadow or fog. We also propose three alternative forms for the function of the transparency distribution. One of these is a simple linear relationship, whereas the other two are nonlinear (a sum of linear and sine wave, and a Gaussian). Ill. 7, bibl. 6 (in English; summaries in English, Russian and Lithuanian).
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