Effectiveness of visual, screen and dynamic variables in animated maps

Abstract

Evaluation of the effectiveness of visual variables for map presentation has been an important research topic in cartography. A number of investigations on this topic have been carried out. However, most of them focused on static maps on paper or screen. Along with the development of computer graphics and Internet technology, animated maps are more and more demanded to represent spatial-temporal data effectively and appropriately. To meet the increasing requirements for dynamic representation and to provide supports for spatial-temporal data visualization, it is necessary to study which and how different variables affect map animation and to evaluate the effectiveness of traditional visual variables and newly included screen and dynamic variables for presentations in animated maps. This study aims to evaluate the effectiveness of these three sets of variables for presentations in animated maps. To evaluate the influence of different variables on human perception on the animated maps, an experimental test was designed and conducted. A set of traffic data were used for generation of animated maps and these maps were evaluated by 732 readers (or subjects in psychology) via Internet. Quantitative approaches were developed and the effectiveness and validity of various variables were compared. Since the most effective variables are faster detected and can arouse more accurate, efficiency and accuracy were considered in each trial of the experiment when a subject (reader) reading animated maps. Efficiency means the time for one to acquire the required information from the animated map, and accuracy means that the correctness of information acquired by map readers (subjects). Results suggest that, in an animated map, (1) for screen variables, "Transparency" and "Blur" are the most effective, "Neon Glow" is effective, and "Resolution" and "Spatter" are not effective; (2) for visual variables, "Color Hue" and "Size" are most effective, "Color Value" and "Color Saturation" are effective, "Shape" is not effective; (3) for the dynamic variable "Rate of Change", "Medium Change" is most effective, "Large Change" is effective, and "Small Change" is not effective. For the dynamic variable "Duration", "7-8 fps" is most effective, and "4-6 fps" and "9-12 fps" are still effective. The empirical results obtained from this study will shed light on understanding how different variables affect human perception on animated maps and give guidance for animated mapping design.