Single-Stage End-to-End Temporal Activity Detection in Untrimmed Videos
Bibliographic record
Abstract
In this paper, we address the problem of human activity detection in temporally untrimmed long video sequences, where the goal is to classify and temporally localize each activity instance in the input video. Inspired by the recent success of the single-stage object detection methods (e.g., SSD [1]), we propose an end-to-end trainable framework that learns task-specific spatio-temporal feature representations of a video sequence using a 3D convolutional neural network followed by a multi-scale detection architecture for direct classification and localization of the activities at varying temporal scales. Our proposed approach sets new state-of-the-art on the highly challenging THUMOS’14 temporal activity detection bench-mark – up from 44.2% mAP to 49.0% mAP (an absolute 4.8% improvement) when the tIoU threshold is set to 0.5 during evaluation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.003 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".