Improving Early Navigation in Time-Lapse Video with Spread-Frame Loading.

Time-lapse videos are often navigated by scrubbing with a slider. When networks are slow or images are large, however, even thumbnail versions load so slowly that scrubbing is limited to the start of the video. We developed a frame-loading technique called spread-loading that enables scrubbing regardless of delivery rate. Spread-loading orders frame delivery to maximize coverage of the entire sequence; this provides a temporal overview of the entire video that can be fully navigated at any time during delivery. The overview initially has a coarse temporal resolution, becoming finer-grained with each new frame. We compared spread-loading with traditional linear loading in a study where participants were asked to find specific episodes in a long time-lapse sequence, using three views with increasing levels of detail. Results show that participants found target episodes significantly and substantially faster with spread-loading, regardless of whether they could click to change the load point. Users rated spread-loading as requiring less effort, and strongly preferred the new technique.