Deep learning (DL) algorithms rely on massive amounts of labeled data. Semi-supervised learning (SSL) and active learning (AL) aim to reduce this label complexity by leveraging unlabeled data or carefully acquiring labels, respectively. In this work, we primarily focus on designing an AL algorithm but first argue for a change in how AL algorithms should be evaluated. Although unlabeled data is readily available in pool-based AL, AL algorithms are usually evaluated by measuring the increase in supervised learning (SL) performance at consecutive acquisition steps. Because this measures performance gains from both newly acquired instances and newly acquired labels, we propose to instead evaluate the label efficiency of AL algorithms by measuring the increase in SSL performance at consecutive acquisition steps. After surveying tools that can be used to this end, we propose our neural pre-conditioning (NPC) algorithm inspired by a Neural Tangent Kernel (NTK) analysis. Our algorithm incorporates the classifier's uncertainty on unlabeled data and penalizes redundant samples within candidate batches to efficiently acquire a diverse set of informative labels. Furthermore, we prove that NPC improves downstream training in the large-width regime in a manner previously observed to correlate with generalization. Comparisons with other AL algorithms show that a state-of-the-art SSL algorithm coupled with NPC can achieve high performance using very few labeled data.

Recent studies have shown that cascade cost volume can play a vital role in deep stereo matching to achieve high resolution depth map with efficient hardware usage. However, how to construct good cascade volume as well as effective sampling for them are still under in-depth study. Previous cascade-based methods usually perform uniform sampling in a predicted disparity range based on variance, which easily misses the ground truth disparity and decreases disparity map accuracy. In this paper, we propose an uncertainty adaptive sampling network (UASNet) featuring two modules: an uncertainty distribution-guided range prediction (URP) model and an uncertainty-based disparity sampler (UDS) module. The URP explores the more discriminative uncertainty distribution to handle the complex matching ambiguities and to improve disparity range prediction. The UDS adaptively adjusts sampling interval to localize disparity with improved accuracy. With the proposed modules, our UASNet learns to construct cascade cost volume and predict full-resolution disparity map directly. Extensive experiments show that the proposed method achieves the highest ground truth covering ratio compared with other cascade cost volume based stereo matching methods. Our method also achieves top performance on both SceneFlow dataset and KITTI benchmark.

Most of the state-of-the-art visual inertial SLAM methods pay less attention to 2D-2D and 3D-2D matching with more reliable features in a long time span, which easily results in continuous estimation drift. In this paper, we propose an efficient drift-free visual-inertial SLAM method by a pose guided feature matching method to re-identify existing features from a spatial-temporal sensitive sub-global map. The re-identified features serve as augmented visual measurements to anchor the current frame and gradually decrease the accumulated error in the long run. When incorporating the measurements into the optimization module, it benefits to build a drift-free global map in the system. Extensive experiments show that our feature re-identification method is both effective and efficient. Specifically, when combining the feature re-identification with the state-of-the-art SLAM method [1], our method achieves 67.3% and 87.5% absolute trajectory error reduction with only a small additional computational cost on two public SLAM benchmark DBs: EuRoC and TUM-VI respectively.

Most of the state-of-the-art visual-inertial SLAM methods pay less attention to the scene structure of man-made environments. In this paper, based on the assumption of multiple local Manhattan worlds (MWs), we propose a Manhattan frame (MF) re-identification method to build relative rotation constraints between MF matching pairs and tightly couple these constraints into global bundle adjust module. Specifically, a coarse-to-fine vanishing point (VP) estimation method and pose guided MF temporal consistency verification method are firstly proposed to improve the accuracy and robustness of MF estimation. Then unreliable MF matching pairs are filtered out by a spatial temporal consistency check. Finally, the relative rotation constraints of the remaining MF matching pairs are combined into global bundle adjustment energy function for further optimization. We have validated our proposed method on both synthetic and real-world datasets. When comparing with the baseline method [1], the real-time absolute trajectory error (ATE) of our proposed method has decreased by 29.1%, 19.8% on TartanAir hospital and EuRoC datasets respectively. Our method also exceeds existing state-of-the-art algorithms on both synthetic and real-world datasets.

The most prevalent scope of interest for OCR applications used to be scanned documents, but it has now shifted towards the natural scene. Despite the change of times, the existing evaluation methods are still based on the old criteria suited better for the past interests. In this paper, we propose PopEval, a novel evaluation approach for the recent OCR interests. The new and past evaluation algorithms were compared through the results on various datasets and OCR models. Compared to the other evaluation methods, the proposed evaluation algorithm was closer to the human's qualitative evaluation than other existing methods. Although the evaluation algorithm was devised as a character-level approach, the comparative experiment revealed that PopEval is also compatible on existing benchmark datasets annotated at word-level. The proposed evaluation algorithm is not only applicable to current end-to-end tasks, but also suggests a new direction to redesign the evaluation concept for further OCR researches.