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name: feature-extraction description: "Route Torchreid feature extraction, model discovery/building, checkpoint loading, distance scoring, rank evaluation, re-ranking, model complexity, ranked-result visualization, and activation-map visualization." disable-model-invocation: true metadata: disco-role: operating license: MIT

Feature Extraction

Use this sub-skill when the task mentions any of the following:

• FeatureExtractor, embeddings, or extracting features from images, numpy arrays, or tensors
• comparing query and gallery sets
• show_avai_models or build_model
• load_pretrained_weights or local checkpoint loading
• compute_distance_matrix, evaluate_rank, or re_ranking
• compute_model_complexity
• visualize_ranked_results or visrank
• activation maps / visactmap / return_featuremaps=True

Route elsewhere

• Training, data managers, Engine.run, or dataset setup → training-evaluation
• ONNX / OpenVINO / TFLite export → model-export
• DML, OSNet-AIN NAS, or PA-100K attribute-recognition projects are excluded long-tail gaps unless a future extension bundles those project sources

Start here

• API reference
• Metrics and re-ranking
• Workflows
• Troubleshooting

Bundled helpers

• scripts/feature_extraction_smoke.py — CPU synthetic build/load/extract/metric smoke with no downloads.
• scripts/compare_embeddings.py — local-weight query/gallery embedding and distance helper.
• scripts/visualize_actmap.py — activation-map wrapper with dry-run preview by default.

Core rules

• Prefer local checkpoint paths. Do not rely on automatic pretrained downloads in helper scripts.
• FeatureExtractor returns a tensor shaped (B, D) and accepts image paths, HWC numpy arrays, or torch.Tensor inputs.
• compute_distance_matrix returns squared Euclidean distances for metric='euclidean'.
• evaluate_rank consumes NumPy distance matrices plus pid/camid arrays and raises if none of the query identities appear in the gallery.
• Activation-map visualization only works when the model forward() accepts return_featuremaps=True and returns 4-D feature maps at eval time.