A quantitative measure for the uniformity of fixation density: The Voronoi method

In order to characterize the uniformity of fixation density, we propose aquantitative measure based on Voronoi diagrams, in which cells are defined around fixation locations. We examined how normalized cell size distributions are related to homogeneous and inhomogeneous fixation densities. Two possible measures for use with the Voronoi method are discussed. Both show good correlation with subjective visual evaluations of the uniformity of fixation densities. Not only are these measures objective and quantitative, they also have a simple intuitive meaning: They may be thought of as reflecting the clustering of fixations.