Paper #31: Trajectory as Creative Intent: Rethinking Drag-Based Interaction in Generative Visual Editing

Trajectory-based interaction, where users draw spatial paths to guide generative editing, has become a popular paradigm across 2D image editing, video generation, 3D scene editing, and human motion synthesis. We present a unified taxonomy of these methods along four dimensions: output modality, trajectory representation, trajectory grounding, and human-AI agency. A striking pattern emerges: across all methods and modalities, the AI operates strictly as a spatial command executor, with collaborative and model-initiated categories entirely vacant. We identify three systematic gaps: ambiguity is resolved by increasing user burden rather than developing interpretive capacity; pipelines are open-loop; and evaluation rewards geometric precision over creative quality. We discuss directions toward systems where trajectories serve as the starting point of creative dialogue rather than commands to be executed.