Two-Stream Action Recognition in Ice Hockey using Player Pose Sequences and Optical Flows
Bibliographic record
Abstract
Current action recognition algorithms in ice hockey do not fully exploit the temporal cues available in video. To solve this challenge, we introduce a two-stream network utilizing player pose sequences and optical flow features for recognizing hockey actions. Player pose sequences are compact representations consisting of frame by frame human and stick joint locations and angles between joints. The optical flow features are obtained by a state-of-the-art optical flow algorithm. The player pose sequences are processed by a two-layered Long short-term memory (LSTM) network. The LSTM output is fused with optical flow features processed by a convolutional neural network (CNN). Experimental results demonstrate the efficacy of the method by achieving 90.48% test accuracy on the HARPET (Hockey Action Recognition Pose Estimation, Temporal) dataset thus surpassing current benchmark by 5%. The network performs better than the current benchmark in segregating similar classes like passing and shooting. It achieves a 90% reduction in parameters and 80% reduction in floating point operations per second (FLOPs) than the benchmark on the HARPET dataset, thus furthering the effectiveness of the network.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".