mlsanityData to 7 Oct 2026

Feature Space Singularity for Out-of-Distribution Detection

arXiv 2011.14654 ↗First posted 30 Nov 2020stat.ML cs.LGcited by 49

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Abstract (arXiv)

Out-of-Distribution (OoD) detection is important for building safe artificial intelligence systems. However, current OoD detection methods still cannot meet the performance requirements for practical deployment. In this paper, we propose a simple yet effective algorithm based on a novel observation: in a trained neural network, OoD samples with bounded norms well concentrate in the feature space. We call the center of OoD features the Feature Space Singularity (FSS), and denote the distance of a sample feature to FSS as FSSD. Then, OoD samples can be identified by taking a threshold on the FSSD. Our analysis of the phenomenon reveals why our algorithm works. We demonstrate that our algorithm achieves state-of-the-art performance on various OoD detection benchmarks. Besides, FSSD also enjoys robustness to slight corruption in test data and can be further enhanced by ensembling. These make FSSD a promising algorithm to be employed in real world. We release our code at urlhttps://github.com/megvii-research/FSSDOoDDetection.

Key facts. Cited by 49 papers in the map (data through 7 Oct 2026). First posted on arXiv 30 Nov 2020.

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Citing papers per year: 2021: 6; 2022: 12; 2023: 14; 2024: 12; 2025: 4; 2026: 1.

49 papers.

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  1. 2021Generalized Out-of-Distribution Detection: A Surveycited by 796
  2. 2021Deep Deterministic Uncertainty: A Simple Baselinecited by 200
  3. 2023A Survey of Safety and Trustworthiness of Large Language Models through the Lens of Verification and Validationcited by 91
  4. 2023LINe: Out-of-Distribution Detection by Leveraging Important Neuronscited by 34
  5. 2022SAFE: Sensitivity-Aware Features for Out-of-Distribution Object Detectioncited by 33
  6. 2022The Familiarity Hypothesis: Explaining the Behavior of Deep Open Set Methodscited by 28
  7. 2022Watermarking for Out-of-distribution Detectioncited by 28
  8. 2023Neuron Activation Coverage: Rethinking Out-of-distribution Detection and Generalizationcited by 28
  9. 2022FiLM-Ensemble: Probabilistic Deep Learning via Feature-wise Linear Modulationcited by 24
  10. 2022Out-of-Distribution Detection with Semantic Mismatch under Maskingcited by 22
  11. 2022Rainproof: An Umbrella To Shield Text Generators From Out-Of-Distribution Datacited by 21
  12. 2024BadActs: A Universal Backdoor Defense in the Activation Spacecited by 19
37 more
  1. 2022Expose Backdoors on the Way: A Feature-Based Efficient Defense against Textual Backdoor Attackscited by 18
  2. 2023Unsupervised Layer-wise Score Aggregation for Textual OOD Detectioncited by 15
  3. 2024A Practical Guide to Sample-based Statistical Distances for Evaluating Generative Models in Sciencecited by 14
  4. 2021Hyperdimensional Feature Fusion for Out-Of-Distribution Detectioncited by 13
  5. 2024Conjugated Semantic Pool Improves OOD Detection with Pre-trained Vision-Language Modelscited by 13
  6. 2023Fine-Tuning Deteriorates General Textual Out-of-Distribution Detection by Distorting Task-Agnostic Featurescited by 12
  7. 20223DOS: Towards 3D Open Set Learning -- Benchmarking and Understanding Semantic Novelty Detection on Point Cloudscited by 11
  8. 2022Extensible Machine Learning for Encrypted Network Traffic Application Labeling via Uncertainty Quantificationcited by 9
  9. 2023MCROOD: Multi-Class Radar Out-Of-Distribution Detectioncited by 9
  10. 2021Harnessing Unrecognizable Faces for Improving Face Recognitioncited by 7
  11. 2022A Continual Learning Framework for Adaptive Defect Classification and Inspectioncited by 7
  12. 2024Advancing Deep Active Learning & Data Subset Selection: Unifying Principles with Information-Theory Intuitionscited by 7
  13. 2021CVAD: A generic medical anomaly detector based on Cascade VAEcited by 6
  14. 2022Holistic Sentence Embeddings for Better Out-of-Distribution Detectioncited by 6
  15. 2023Reconstruction-based Out-of-Distribution Detection for Short-Range FMCW Radarcited by 6
  16. 2024Diffusion-based Layer-wise Semantic Reconstruction for Unsupervised Out-of-Distribution Detectioncited by 5
  17. 2023HOOD: Real-Time Human Presence and Out-of-Distribution Detection Using FMCW Radarcited by 4
  18. 2023HAROOD: Human Activity Classification and Out-of-Distribution Detection with Short-Range FMCW Radarcited by 4
  19. 2024Proto-OOD: Enhancing OOD Object Detection with Prototype Feature Similaritycited by 4
  20. 2023PatchBackdoor: Backdoor Attack against Deep Neural Networks without Model Modificationcited by 3
  21. 2025Synthesizing Near-Boundary OOD Samples for Out-of-Distribution Detectioncited by 3
  22. 2021Meta Learning Low Rank Covariance Factors for Energy-Based Deterministic Uncertaintycited by 2
  23. 2023Interpretable Out-Of-Distribution Detection Using Pattern Identificationcited by 2
  24. 2024Out-of-Distribution Detection and Data Drift Monitoring using Statistical Process Controlcited by 2
  25. 2024Out-of-Distribution Detection using Neural Activation Priorcited by 2
  26. 2024FOOD: Facial Authentication and Out-of-Distribution Detection with Short-Range FMCW Radarcited by 2
  27. 2022Learning by Erasing: Conditional Entropy based Transferable Out-Of-Distribution Detectioncited by 1
  28. 2023SIO: Synthetic In-Distribution Data Benefits Out-of-Distribution Detectioncited by 1
  29. 2023Deep Neural Networks Tend To Extrapolate Predictablycited by 1
  30. 2024Collaborative Knowledge Distillation via a Learning-by-Education Node Communitycited by 1
  31. 2024ITP: Instance-Aware Test Pruning for Out-of-Distribution Detectioncited by 1
  32. 2025Hypercone Assisted Contour Generation for Out-of-Distribution Detectioncited by 1
  33. 2023GROOD: GRadient-Aware Out-of-Distribution Detectioncited by 0
  34. 2024Enhancing Out-of-Distribution Detection with Multitesting-based Layer-wise Feature Fusioncited by 0
  35. 2025FARE: A Deep Learning-Based Framework for Radar-based Face Recognition and Out-of-distribution Detectioncited by 0
  36. 2025Latent space analysis and generalization to out-of-distribution datacited by 0
  37. 2026Training-Free Out-of-Distribution Detection for Pathology Whole-Slide Imagescited by 0