Exploring the relative importance of crossing number and crossing angle

Recent research has indicated that human graph reading performance can be affected by the size of crossing angle. Crossing angle is closely related to another aesthetic criterion: number of edge crossings. Although crossing number has been previously identified as the most important aesthetic, its relative impact on performance of human graph reading is unknown, compared to crossing angle. In this paper, we present an exploratory user study investigating the relative importance between crossing number and crossing angle. This study also aims to further examine the effects of crossing number and crossing angle not only on task performance measured as response time and accuracy, but also on cognitive load and visualization efficiency. The experimental results reinforce the previous findings of the effects of the two aesthetics on graph comprehension. The study demonstrates that on average these two closely related aesthetics together explain 33% of variance in the four usability measures: time, accuracy, mental effort and visualization efficiency, with about 38% of the explained variance being attributed to the crossing angle. Copyright © 2010 ACM

Animating Predator and Prey Fish Interactions

Schooling behavior is one of the most salient social and group activities among fish. They form schools for social reasons like foraging, mating and escaping from predators. Animating a school of fish is difficult because they are large in number, often swim in distinctive patterns that is they take the shape of long thin lines, squares, ovals or amoeboid and exhibit complex coordinated patterns especially when they are attacked by a predator. Previous work in computer graphics has not provided satisfactory models to simulate the many distinctive interactions between a school of prey fish and their predator, how does a predator pick its target? and how does a school of fish react to such attacks? This dissertation presents a method to simulate interactions between prey fish and predator fish in the 3D world based on the biological research findings. Firstly, a model is described by representing a school of fish as a complex network information flow with structural properties. Using this model, a predator fish targeting isolated peripheral fish is simulated. Secondly, the escape behavior state machine model and escape maneuvers exhibited by fish schools are described. The escape maneuvers include compact, avoid, fast avoid, skitter, fountain, flash, ball, split, join, herd, vacuole, and hourglass are identified in the biological studies. This proposed escape behavior animation model can free an animator from dealing with the low-level animations but instead, control the fish behavior on a higher level by modifying a state machine and a small set of system parameters. With the state machine and relatively few system parameters, the proposed system is stable, predictable, and easy to tune, which represent important properties for animators to control the outcome. This system is developed in Unity (3D). In addition, a plug-in is also developed for full-fledged graphics tool Blender software to simulate escape maneuvers. The animator has to simply select escape maneuvers, adjust parameters and work on animating predator using keyframe method. It does not deal with the state machine model. The proposed model is useful not only in generating group behaviors but also in scientific visualization tool for studying fish behavior