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Unformatted text preview: Motion Cues for Illustration of Skeletal Motion Capture Data Simon Bouvier-Zappa Victor Ostromoukhov Pierre Poulin LIGUM, Dep. I.R.O., Universite de Montreal (a) (b) (c) (d) Figure 1: Non-photorealistic illustration of motion capture sequences: (a) spin kick, (b) dancing pirouette, (c) cart wheel, (d) bending-over. Each motion is emphasized using motion arrows, noise waves, and/or stroboscopic motion. Abstract There are many applications for which it is necessary to illustrate motion in a static image using visual cues which do not repre- sent a physical entity in the scene, yet are widely understood to convey motion. For example, consider the task of illustrating the desired movements for exercising, dancing, or a given sport tech- nique. Traditional artists have developed techniques to specify de- sired movements precisely (technical illustrators) and suggest mo- tion (cartoonists) in an image. In this paper, we present an interactive system to synthesize a 2D image of an animated character by generating artist-inspired motion cues derived from 3D skeletal motion capture data. The primary cues include directed arrows, noise waves, and stroboscopic mo- tion. First, the user decomposes the animation into short sequences containing individual motions which can be represented by visual cues. The system then allows the user to determine a suitable view- point for illustrating the movement, to select the proper level in the joint hierarchy, as well as to fine-tune various controls for the depic- tion of the cues themselves. While the system does provide adapted default values for each control, extracted from the motion capture data, it allows fine-tuning for greater expressiveness. Moreover, these cues are drawn in real time, and maintain a coherent display with changing viewpoints. We demonstrate the benefit of our interactive system on various motion capture sequences. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and RealismAnimation I.3.3 [Computer Graphics]: Picture/Image GenerationDisplay and Viewing algorithms 1 Introduction The verbal conveyance of an idea is a powerful medium for shar- ing precise thoughts. However, a well-illustrated image may also bring an instant understanding of the subject matter. For example, Tufte  says that to document and explain a process, to make verbs visible, is at the heart of information design . This princi- ple has always been a concern in illustrations of all kinds, from strict technical designs to more permissive cartoon comics. Visual cues are powerful tools in graphic arts that compensate the inher- ent limitations of the visualization medium. Motion cues fall into this category, emphasizing temporal information from a dynamic 3D world into a static 2D representation....
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- Spring '08