In the field of forensic science, diatom test is widely utilized to determine the cause and location of death for bodies found in water. Diatom detection plays an important role in the diatom test. However, diatom detection faces challenges due to the imbalanced distribution of diatom features and the complexity of these features. To address these two challenges, we propose DiaDet-R, a diatom rotated detector for drowning diagnosis. Specifically, to tackle the first challenge of feature distribution imbalance, we perform customized data augmentation on our self-established diatom dataset to increase sample diversity. Further, we introduce the Low-level Enhancement Path Aggregation Feature Pyramid Network (LEPAFPN) to better extract tail features of intra-class features that exhibit a long-tail distribution. To address the second challenge of the feature complexity, we propose three strategies: (1) we devise a basic building block, Double Inception Depth-wise Convolution (Double IDC), to enhance the detector’s long-distance modeling capability; (2) we improve the horizontal detector to a rotated object detector to address the issues of overlapping and extensive invalid backgrounds caused by arbitrary angles and shapes of diatom targets; (3) to solve the feature misalignment issue in rotated object detection, we propose the Rotated Alignment Head (RAHead) to align target features. Extensive experimental results on our self-established diatom dataset show that DiaDet-R achieves mAP50 and mAP75 of 95.73% and 89.99%, respectively, with reduced model parameters and GFLOPs to 4.34M and 18.48G, validating that DiaDet-R can detect diatoms quickly and accurately, outperforming mainstream rotated detectors.
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