AFTERMOTION began as an attempt to study and reconstruct an existing interactive motion-visualization model based on a field of vertical lines responding to the movement of the audience. After reconstructing the core interaction, the system was developed into a configurable browser-based application designed for rapid testing, exhibition use and adaptation to different visual projects. My contribution focused on rebuilding the interaction logic for the web, developing a practical control interface and extending the visual behavior of the system. New features include adjustable motion parameters, camera calibration, temporary color traces, motion memory, responsive sound and the gradual return of both the lines and color field to stillness. Unlike workflows that depend on dedicated visual-programming software such as TouchDesigner, AFTERMOTION runs directly inside a web browser and can operate with a standard camera, without requiring a specialized visual system.