Robust detection of vulnerable road users is a safety critical requirement for the deployment of autonomous vehicles in heterogeneous traffic. One of the most complex outstanding challenges is that of partial occlusion where a target object is only partially available to the sensor due to obstruction by another foreground object. A number of leading pedestrian detection benchmarks provide annotation for partial occlusion, however each benchmark varies greatly in their definition of the occurrence and severity of occlusion. Recent research demonstrates that a high degree of subjectivity is used to classify occlusion level in these cases and occlusion is typically categorized into 2 to 3 broad categories such as partially and heavily occluded. This can lead to inaccurate or inconsistent reporting of pedestrian detection model performance depending on which benchmark is used. This research introduces a novel, objective benchmark for partially occluded pedestrian detection to facilitate the objective characterization of pedestrian detection models. Characterization is carried out on seven popular pedestrian detection models for a range of occlusion levels from 0-99%, in order to demonstrate the efficacy and increased analysis capabilities of the proposed characterization method. Results demonstrate that pedestrian detection performance degrades, and the number of false negative detections increase as pedestrian occlusion level increases. Of the seven popular pedestrian detection routines characterized, CenterNet has the greatest overall performance, followed by SSDlite. RetinaNet has the lowest overall detection performance across the range of occlusion levels.

翻译：弱势道路使用者的鲁棒检测是自动驾驶汽车在混合交通中部署的关键安全要求。最具挑战性的遗留问题之一是部分遮挡，即目标物体因被另一前景物体遮挡而仅部分暴露于传感器。多个主流行人检测基准提供了部分遮挡的标注，但每个基准对遮挡发生及严重程度的定义差异显著。近期研究表明，这些案例中遮挡级别的分类存在高度主观性，通常将遮挡划分为2到3个宽泛类别（如部分遮挡和严重遮挡）。这可能导致根据不同基准汇报的行人检测模型性能不准确或不一致。本研究引入了一种新颖、客观的部分遮挡行人检测基准，以促进行人检测模型的客观表征。通过对七个主流行人检测模型在0-99%遮挡范围内进行表征，验证了所提表征方法的有效性和增强分析能力。结果表明，随着行人遮挡程度增加，行人检测性能下降，假阴性检测数量上升。在七种主流行人检测方法中，CenterNet整体性能最佳，其次为SSDlite，而RetinaNet在各级遮挡下整体检测性能最低。