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Clustering video scenes. Nebojsa Jojic. Six break points vs. six things in video. Traditional video segmentation: Find breakpoints Example: MovieMaker (cut and paste) Our goal: Find possibly recurring scenes or objects. timeline. 1. 2. 3. 2. 4. 1. 4. 3. 2. 3. 2. 3. 5. 6.
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Clustering video scenes Nebojsa Jojic
Six break points vs. six things in video • Traditional video segmentation: Find breakpoints Example: MovieMaker (cut and paste) • Our goal: Find possibly recurring scenes or objects timeline 1 2 3 2 4 1 4 3 2 3 2 3 5 6
Six break points vs. six things in video • Differences: timeline • A class is detected at multiple intervals on the timeline. For example, class 1 models a baby’s face. Break pointers miss it at the second occurrence. The class occurs more in the rest of the sequence 1 2 3 2 4 1 4 3 2 3 2 3 5 6
Six break points vs. six things in video • Differences: timeline One long shot contains a pan of the camera back and forth among three scenes (classes 2,3 and 5) 1 2 3 2 4 1 4 3 2 3 2 3 5 6
Six break points vs. six things in video • Traditional video segmentation: Find breakpoints Example: MovieMaker (cut and paste) timeline Two shots detected just because the camera was turned off and then on with a slightly different vantage point are considered a single scene class. 1 2 3 2 4 1 4 3 2 3 2 3 5 6
Model • Appearance mean variance • Camera/object motion • Temporal constraints • Unsupervised learning – the only input is the video
TMG: Fitting a generative model Class index Class mean (representative image) Shift Mean with added variability Transformed (shifted image) Transformed image with added non-uniform noise
Mean • One class summary • Variance 5 classes Example • Hand-held camera • Moving subject • Cluttered background DATA
Current implementation • DShow filter for frame clustering (5-15 frames/sec!) • Translation invariance • On-line learning algorithm • Classes repeating across video • Potential applications: • Video segmentation • Content based search/retrieval • Short video summary creation • DVD chapter creation
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Grouping based on class transition patterns class … time