针对野生动物图像长尾分布问题,提出高效识别方法并实现99.4%准确率。
Long-tailed Species Recognition in the NACTI Wildlife Dataset
- 结合先进长尾损失函数与正则化策略优化模型
- 在370万张图像上达99.40%准确率,显著优于基线
- 适用于野外复杂场景下物种识别,尤其对稀有物种有效
自然世界中大多数‘野外’数据集存在严重长尾类别不平衡问题。以北美相机陷阱图像(NACTI)数据集为例,最大类别的样本量超过370万张图像的50%。基于PyTorch Wildlife模型,本文系统研究了多种长尾识别(LTR)方法在该数据集上的表现,涵盖不同LTR损失函数及敏感正则化技术。最优配置在测试集上达到99.40%的Top-1准确率,远超使用标准交叉熵和Adam优化器的95.51%基线。该性能也优于此前在MLWIC2上报告的96.8%结果(但其数据划分、优化器和评估协议部分未公开)。为评估域偏移(如夜间拍摄、遮挡、运动模糊)影响,我们从ENA-Detection构建去偏测试集,实验优化的长尾增强模型取得52.55%准确率(相比WCE损失的51.20%),展现出更强泛化能力。研究还发现,结合前沿LTR损失与优化调度策略可持续提升性能。最后讨论了当前方法无法充分解决的缺陷,包括极端域偏移下‘尾部’类别的灾难性崩溃。为确保可复现性,所有数据划分、核心代码与完整网络权重均已公开。
原文摘要 · Abstract (English)
As most ''in the wild'' data collections of the natural world, the North America Camera Trap Images (NACTI) dataset shows severe long-tailed class imbalance, noting that the largest 'Head' class alone covers >50% of the 3.7M images in the corpus. Building on the PyTorch Wildlife model, we present a systematic study of Long-Tail Recognition methodologies for species recognition on the NACTI dataset covering experiments on various LTR loss functions plus LTR-sensitive regularisation. Our best configuration achieves 99.40% Top-1 accuracy on our NACTI test data split, substantially improving over a 95.51% baseline using standard cross-entropy with Adam. This also improves on previously reported top performance in MLWIC2 at 96.8% albeit using partly unpublished (potentially different) partitioning, optimiser, and evaluation protocols. To evaluate domain shifts (e.g. night-time captures, occlusion, motion-blur) towards other datasets we construct a Reduced-Bias Test set from the ENA-Detection dataset where our experimentally optimised long-tail enhanced model achieves leading 52.55% accuracy (up from 51.20% with WCE loss), demonstrating stronger generalisation capabilities under distribution shift. We document the consistent improvements of LTR-enhancing scheduler choices in this NACTI wildlife domain, particularly when in tandem with state-of-the-art LTR losses. We finally discuss qualitative and quantitative shortcomings that LTR methods cannot sufficiently address, including catastrophic breakdown for 'Tail' classes under severe domain shift. For maximum reproducibility we publish all dataset splits, key code, and full network weights.
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