Rotosketch is an intuitive tool for sketching, doodling and notating on top of video, such that the marks that are made are linked in time with the video. This allows the user to draw strokes along the the axis of time, as well as the normal x and y axes, and for those strokes to augment, analyze, interpret, or even obliterate a video sequence.
The software, created by Zachary Lieberman together with Scott de la Hunta, and Susan Rethorst, explores how technology might be used to facilitate the dance making process in a creative and organic manner. "We were constantly asking ourselves, what would the "photoshop" for dance look like?" writes Lieberman.
Tutorial on the website explaining how to try the alpha version of rotosketch.
Via splines in space.