Dynamosaics: Video Mosaics with Non-Chronological Time
Alex Rav-Acha, Yael Pritch, Dani Lischinski, Shmuel Peleg
The manipulations of time in video editing, which enable to control the chronological time of events, are explored. These time manipulations include slowing down (or postponing) some activities while speeding up (or advancing) other activities. When a video camera scans a scene, aligning all the activities to a single time interval will result in a panoramic movie. Time manipulations are obtained by first constructing an aligned space-time volume from the input video, and then sweeping a continuous 2D slice (time front) through that volume, generating a new sequence of images.
For dynamic scenes, aligning the input video frames poses an important challenge. We propose to align dynamic scenes using a new notion of ``dynamics constancy'' which is more appropriate than the traditional assumption of ``brightness constancy''. We also propose a solution to the shearing of moving objects due to the slicing of the space-time volume. To overcome this problem, we formulate it as a problem of finding a minimal cut in a 4D graph, and solve it using max-flow methods.
Iguazu Falls. Click on pictures to view Mpeg video.
More results: Dynamic Panoramas | Dynamosaicing Using 4D Min-Cut | Evolving Time Fronts