3D animations are an effective method to learn about complex dynamic phenomena, such as mesoscale biological processes. The animators' goals are to convey a sense of the scene's overall complexity while, at the same time, visually guiding the user through a story of subsequent events embedded in the chaotic environment. Animators use a variety of visual emphasis techniques to guide the observers' attention through the story, such as highlighting, halos -- or by manipulating motion parameters of the scene. In this paper, we investigate the effect of smoothing the motion of contextual scene elements to attract attention to focus elements of the story exhibiting high-frequency motion. We conducted a crowdsourced study with 108 participants observing short animations with two illustrative motion smoothing strategies: geometric smoothing through noise reduction of contextual motion trajectories and visual smoothing through motion blur of \rev{context} items. We investigated the observers' ability to follow the story as well as the effect of the techniques on speed perception in a molecular scene. Our results show that moderate motion blur significantly improves users' ability to follow the story. Geometric motion smoothing is less effective but increases the visual appeal of the animation. However, both techniques also slow down the perceived speed of the animation. We discuss the implications of these results and derive design guidelines for animators of complex dynamic visualizations.

翻译：三维动画是理解复杂动态现象（如介观生物过程）的有效方法。动画师的目标是在传达场景整体复杂性的同时，通过视觉引导用户跟随嵌入在混沌环境中的连续事件故事。动画师采用多种视觉强调技术来引导观察者的注意力，例如高亮、光晕，或通过操控场景的运动参数。本文研究了平滑上下文场景元素的运动以吸引注意力至呈现高频运动的故事情节焦点元素的效果。我们进行了一项众包研究，招募108名参与者观察采用两种示意性运动平滑策略的短动画：通过对上下文运动轨迹进行降噪处理实现的几何平滑，以及通过对上下文对象应用运动模糊实现的视觉平滑。我们考察了观察者跟随故事的能力以及这些技术对分子场景中速度感知的影响。结果表明，适度的运动模糊显著提升了用户跟随故事的能力。几何运动平滑效果较弱但能增加动画的视觉吸引力。然而，两种技术均会降低动画的感知速度。我们讨论了这些结果的意义，并为复杂动态可视化动画师推导出了设计指南。