Domain adaptation adapts models to various scenes with different appearances. In this field, active domain adaptation is crucial in effectively sampling a limited number of data in the target domain. We propose an active domain adaptation method for object detection, focusing on quantifying the undetectability of objects. Existing methods for active sampling encounter challenges in considering undetected objects while estimating the uncertainty of model predictions. Our proposed active sampling strategy addresses this issue using an active learning approach that simultaneously accounts for uncertainty and undetectability. Our newly proposed False Negative Prediction Module evaluates the undetectability of images containing undetected objects, enabling more informed active sampling. This approach considers previously overlooked undetected objects, thereby reducing false negative errors. Moreover, using unlabeled data, our proposed method utilizes uncertainty-guided pseudo-labeling to enhance domain adaptation further. Extensive experiments demonstrate that the performance of our proposed method closely rivals that of fully supervised learning while requiring only a fraction of the labeling efforts needed for the latter.

A Manhattan world lying along cuboid buildings is useful for camera angle estimation. However, accurate and robust angle estimation from fisheye images in the Manhattan world has remained an open challenge because general scene images tend to lack constraints such as lines, arcs, and vanishing points. To achieve higher accuracy and robustness, we propose a learning-based calibration method that uses heatmap regression, which is similar to pose estimation using keypoints, to detect the directions of labeled image coordinates. Simultaneously, our two estimators recover the rotation and remove fisheye distortion by remapping from a general scene image. Without considering vanishing-point constraints, we find that additional points for learning-based methods can be defined. To compensate for the lack of vanishing points in images, we introduce auxiliary diagonal points that have the optimal 3D arrangement of spatial uniformity. Extensive experiments demonstrated that our method outperforms conventional methods on large-scale datasets and with off-the-shelf cameras.

Action recognition is a key technology for many industrial applications. Methods using visual information such as images are very popular. However, privacy issues prevent widespread usage due to the inclusion of private information, such as visible faces and scene backgrounds, which are not necessary |for recognizing user action. In this paper, we propose a privacy-preserving action recognition by ultrasound active sensing. As action recognition from ultrasound active sensing in a non-invasive manner is not well investigated, we create a new dataset for action recognition and conduct a comparison of features for classification. We calculated feature values by focusing on the temporal variation of the amplitude of ultrasound reflected waves and performed classification using a support vector machine and VGG for eight fundamental action classes. We confirmed that our method achieved an accuracy of 97.9% when trained and evaluated on the same person and in the same environment. Additionally, our method achieved an accuracy of 89.5% even when trained and evaluated on different people. We also report the analyses of accuracies in various conditions and limitations.

In this paper, we address the challenges of representing feature distributions which have multimodality within a class in deep neural networks. Existing online clustering methods employ sub-centroids to capture intra-class variations. However, conducting online clustering faces some limitations, i.e., online clustering assigns only a single sub-centroid to a feature vector extracted from a backbone and ignores the relationship between the other sub-centroids and the feature vector, and updating sub-centroids in an online clustering manner incurs significant storage costs. To address these limitations, we propose a novel method utilizing orthonormal matrices instead of sub-centroids for relaxing discrete assignments into continuous assignments. We update the orthonormal matrices using a gradient-based method, which eliminates the need for online clustering or additional storage. Experimental results on the CIFAR and ImageNet datasets exhibit that the proposed method outperforms current online clustering techniques in classification accuracy, sub-category discovery, and transferability, providing an efficient solution to the challenges posed by complex recognition targets.