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| (a) fish | (b) spaghetti | (c) scraps | 
Our method synthesizes a variety of repetitive spatial-temporal phenomena, such as herd, threads and sheets, via a combination of constrained optimization and data driven computation. Please refer to the accompanying video for corresponding animations of our results.
            Many natural phenomena consist of geometric elements with dynamic motions characterized
            by small scale repetitions over large scale structures, such as particles, herds,
            threads, and sheets. Due to their ubiquity, controlling the appearance and behavior
            of such phenomena is important for a variety of graphics applications. However,
            such control is often challenging; the repetitive elements are often too numerous
            for manual edit, while their overall structures are often too versatile for fully
            automatic computation.
            
            
            We propose a method that facilitates easy and intuitive controls at both scales:
            high-level structures through spatial-temporal output constraints (e.g. overall
            shape and motion of the output domain), and low-level details through small input
            exemplars (e.g. element arrangements and movements). These controls are suitable
            for manual specification, while the corresponding geometric and dynamic repetitions
            are suitable for automatic computation. Our system takes such user controls as inputs,
            and generates as outputs the corresponding repetitions satisfying the controls.
            
            
            Our method, which we call dynamic element textures, aims to produce such
            controllable repetitions through a combination of constrained optimization (satisfying
            controls) and data driven computation (synthesizing details). We use spatial-temporal
            samples as the core representation for dynamic geometric elements. We propose analysis
            algorithms for decomposing small scale repetitions from large scale themes, as well
            as synthesis algorithms for generating outputs satisfying user controls. Our method
            is general, producing a range of artistic effects that previously required disparate
            and specialized techniques.
Dynamic, element, texture, control, constraints, optimization, geometry, animation, analysis, synthesis