Animal pose estimation is often constrained by the scarcity of annotations and the diversity of scenarios and species. The pseudo-label generation based unsupervised domain adaptation paradigm, which discriminates the predicted keypoints of unlabeled data based on the skeleton position consistency, has demonstrated effectiveness for such problems. However, existing methods generate pseudo-labels with massive false positives, because they cannot effectively distinguish sample pairs with the same errors. In this study, we propose a cross-domain animal pose estimation model from a novel perspective of skeleton anomaly learning. We construct a graph contrastive learning mechanism to acquire the skeleton anomaly-aware knowledge, which enables the generation of accurate pseudo-labels for target domain and imposes graph constraint on unlabeled data. And a skeleton anomaly-feedback based domain adaptation framework is designed to facilitate implicit alignment of object-specific features and joint training of cross-domain. Besides, we propose a novel rat pose dataset named UDARP-9.4K to address the gap of small-sized animal pose datasets encompassing diverse experimental scenarios. The related datasets are reviewed and evaluated in detail. Extensive experiments are conducted on UDARP-9.4K and two public datasets to demonstrate the superiority of the proposed model in cross-scenarios and cross-species animal pose estimation tasks. Further analysis reveals the effectiveness of the proposed model for skeleton structure feature learning.The UDARP-9.4K dataset is available here.

In the field of pose estimation, keypoint representations can take the form of Gaussian heatmaps, classification vectors, or direct coordinates. However, the current networks suffer from a lack of consistency with these keypoint representations. They only accommodate these representations in the final layer, resulting in suboptimal efficiency and requiring a high number of parameters or computational resources. In this paper, we propose a simple yet efficient plug-and-play module, named the Implicit Decouple Module (IDM), which decouples features into two parts along the x-y axes and aggregates features in a direction-aware manner. This approach implicitly fuses direction-specific coordinate information, improving the consistency with the keypoint representations, especially in vector form. Furthermore, we introduce a fully convolutional backbone network, named the Implicit Decouple Network (IDN), which incorporates IDM without the need to maintain high-resolution features, dense multi-level feature fusion, or lots of repeated stages, while still achieving high performance. In experiments on the COCO dataset, our basic IDN without pre-training can outperform HRNet (28.5M) by 2.4 AP with 18.2M parameters, and even surpass some transformer-based methods. In the lightweight model scenario, our model outstrips Lite-HRNet by 3.9 AP with only 2.5M parameters. We also evaluate our model on the person instance segmentation task and other datasets, demonstrating its generality and effectiveness. http(s)://znk.ink/su/mm23idn.

Although recent work has achieved great progress in human pose estimation (HPE), most methods show limitations in either inference speed or accuracy. In this paper, we propose a fast and accurate end-to-end HPE method, which is specifically designed to overcome the commonly encountered jitter box, defective box and ambiguous box problems of box-based methods, e.g. Mask R-CNN. Concretely, 1) we propose the ROIGuider to aggregate box instance features from all feature levels under the guidance of global context instance information. Further, 2) the proposed Center Line Branch is equipped with a Dichotomy Extended Area algorithm to adaptively expand each instance box area, and Ambiguity Alleviation strategy to eliminate duplicated keypoints. Finally, 3) to achieve efficient multi-scale feature fusion and real-time inference, we design a novel Trapezoidal Network (TNet) backbone. Experimenting on the COCO dataset, our method achieves 68.1 AP at 25.4 fps, and outperforms Mask-RCNN by 8.9 AP at a similar speed. The competitive performance on the HPE and person instance segmentation tasks over the state-of-the-art models show the promise of the proposed method. The source code will be made available at https://github.com/zlcnup/CGANet.