Point cloud completion, as the upstream procedure of 3D recognition and segmentation, has become an essential part of many tasks such as navigation and scene understanding. While various point cloud completion models have demonstrated their powerful capabilities, their robustness against adversarial attacks, which have been proven to be fatally malicious towards deep neural networks, remains unknown. In addition, existing attack approaches towards point cloud classifiers cannot be applied to the completion models due to different output forms and attack purposes. In order to evaluate the robustness of the completion models, we propose PointCA, the first adversarial attack against 3D point cloud completion models. PointCA can generate adversarial point clouds that maintain high similarity with the original ones, while being completed as another object with totally different semantic information. Specifically, we minimize the representation discrepancy between the adversarial example and the target point set to jointly explore the adversarial point clouds in the geometry space and the feature space. Furthermore, to launch a stealthier attack, we innovatively employ the neighbourhood density information to tailor the perturbation constraint, leading to geometry-aware and distribution-adaptive modifications for each point. Extensive experiments against different premier point cloud completion networks show that PointCA can cause a performance degradation from 77.9% to 16.7%, with the structure chamfer distance kept below 0.01. We conclude that existing completion models are severely vulnerable to adversarial examples, and state-of-the-art defenses for point cloud classification will be partially invalid when applied to incomplete and uneven point cloud data.

3D object detection received increasing attention in autonomous driving recently. Objects in 3D scenes are distributed with diverse orientations. Ordinary detectors do not explicitly model the variations of rotation and reflection transformations. Consequently, large networks and extensive data augmentation are required for robust detection. Recent equivariant networks explicitly model the transformation variations by applying shared networks on multiple transformed point clouds, showing great potential in object geometry modeling. However, it is difficult to apply such networks to 3D object detection in autonomous driving due to its large computation cost and slow reasoning speed. In this work, we present TED, an efficient Transformation-Equivariant 3D Detector to overcome the computation cost and speed issues. TED first applies a sparse convolution backbone to extract multi-channel transformation-equivariant voxel features; and then aligns and aggregates these equivariant features into lightweight and compact representations for high-performance 3D object detection. On the highly competitive KITTI 3D car detection leaderboard, TED ranked 1st among all submissions with competitive efficiency.

与标准动态范围（SDR）视频相比，高动态范围（HDR）视频可以代表更大的亮度和色彩范围，并且正迅速成为行业标准。与传统SDR视频相比，HDR视频具有更具挑战性的捕获，传输和显示要求。凭借其更大的深度，高级的电流传输功能以及更广泛的颜色范围，因此需要专门设计用于预测HDR视频质量的视频质量算法。为此，我们介绍了HDR视频的首次公开发布的大规模主观研究。我们研究扭曲的影响，例如压缩和混叠对HDR视频质量的影响。我们还通过在黑暗实验室环境和更明亮的客厅环境中进行研究来研究环境照明对HDR视频感知质量的影响。总共有66名受试者参加了这项研究，并收集了20,000多个意见分数，这使得这成为有史以来最大的HDR视频质量研究。我们预计，该数据集将成为研究人员为HDR视频开发更好的感知质量模型的宝贵资源。

随着电子商务的繁荣，旨在按照预测的有用性分数对产品评论进行分类的多模式审查帮助预测（MRHP）已成为研究热点。此任务的先前工作集中于基于注意力的模态融合，信息集成和关系建模，该模型主要暴露了以下缺点：1）由于其不加区分的注意公式，该模型可能无法捕获真正的基本信息； 2）缺乏适当的建模方法，可以充分利用提供的数据之间的相关性。在本文中，我们提出了SANCL：MRHP的选择性关注和自然对比学习。 SANCL采用基于探测的策略来对更大意义的区域进行高度注意权重。它还基于数据集中的自然匹配属性构建了对比度学习框架。两个基准数据集的实验结果（三个类别）表明，SANCL在记忆消耗较低的情况下实现了最先进的基线性能。

深度神经网络的兴起为优化推荐系统提供了重要的驱动力。但是，推荐系统的成功在于精致的建筑制造，因此呼吁神经建筑搜索（NAS）进一步改善其建模。我们提出了NASREC，它是一种训练单个超级网的范式，并通过重量共享有效地产生丰富的模型/子构造。为了克服数据多模式和体系结构异质性挑战，NASREC建立了一个大型的超级网（即搜索空间），以搜索完整的体系结构，而SuperNet结合了多功能操作员的选择和密集的连接性选择，并使人类的密集连接性最小化。 Nasrec的规模和异质性在搜索中构成了挑战，例如训练效率低下，操作员不平衡和降级等级相关性。我们通过提出单操作员任何连接采样，操作员平衡互动模块和训练后微调来应对这些挑战。我们对三个点击率（CTR）预测基准测试的结果表明，NASREC可以胜过手动设计的模型和现有的NAS方法，从而实现最先进的性能。

自我关注在捕获远程关系时，在提高视觉任务的表现，例如图像分类和图像标题等方面，突出的能力。然而，自我关注模块高度依赖于查询键值特征之间的点产品乘法和维度对齐，这导致两个问题：（1）点产品乘法导致穷举和冗余计算。 （2）由于视觉特征图通常出现作为多维张量，重塑张量特征的尺度，以适应尺寸对齐可能会破坏张量特征图的内部结构。为了解决这些问题，本文提出了一种具有其变体的自我关注插入模块，即合成张量变换（STT），用于直接处理图像张量特征。如果在查询键值之间计算点 - 产品乘法，则基本STT由张量转换组成，以从视觉信息中学习合成注意力。 STT系列的有效性在图像分类和图像标题上验证。实验表明，建议的STT实现了竞争性能，同时保持鲁棒性与基于视觉任务的自我关注相比。

随着自我关注机制的发展，变压器模型已经在计算机视觉域中展示了其出色的性能。然而，从完全关注机制带来的大规模计算成为内存消耗的沉重负担。顺序地，记忆的限制降低了改善变压器模型的可能性。为了解决这个问题，我们提出了一种名为耦合器的新的记忆经济性注意力机制，它将注意力映射与两个子矩阵分成并从空间信息中生成对准分数。应用了一系列不同的尺度图像分类任务来评估模型的有效性。实验结果表明，在ImageNet-1K分类任务上，与常规变压器相比，耦合器可以显着降低28％的存储器消耗，同时访问足够的精度要求，并且在占用相同的内存占用时表达了0.92％。结果，耦合器可以用作视觉任务中的有效骨干，并提供关于研究人员注意机制的新颖视角。

本文回顾了关于压缩视频质量增强质量的第一个NTIRE挑战，重点是拟议的方法和结果。在此挑战中，采用了新的大型不同视频（LDV）数据集。挑战有三个曲目。Track 1和2的目标是增强HEVC在固定QP上压缩的视频，而Track 3旨在增强X265压缩的视频，以固定的位速率压缩。此外，轨道1和3的质量提高了提高保真度（PSNR）的目标，以及提高感知质量的2个目标。这三个曲目完全吸引了482个注册。在测试阶段，分别提交了12个团队，8支球队和11支球队，分别提交了轨道1、2和3的最终结果。拟议的方法和解决方案衡量视频质量增强的最先进。挑战的首页：https：//github.com/renyang-home/ntire21_venh

High network communication cost for synchronizing gradients and parameters is the well-known bottleneck of distributed training. In this work, we propose TernGrad that uses ternary gradients to accelerate distributed deep learning in data parallelism. Our approach requires only three numerical levels {−1, 0, 1}, which can aggressively reduce the communication time. We mathematically prove the convergence of TernGrad under the assumption of a bound on gradients. Guided by the bound, we propose layer-wise ternarizing and gradient clipping to improve its convergence. Our experiments show that applying TernGrad on AlexNet doesn't incur any accuracy loss and can even improve accuracy. The accuracy loss of GoogLeNet induced by TernGrad is less than 2% on average. Finally, a performance model is proposed to study the scalability of TernGrad. Experiments show significant speed gains for various deep neural networks. Our source code is available 1 .

High demand for computation resources severely hinders deployment of large-scale Deep Neural Networks (DNN) in resource constrained devices. In this work, we propose a Structured Sparsity Learning (SSL) method to regularize the structures (i.e., filters, channels, filter shapes, and layer depth) of DNNs. SSL can: (1) learn a compact structure from a bigger DNN to reduce computation cost; (2) obtain a hardware-friendly structured sparsity of DNN to efficiently accelerate the DNN's evaluation. Experimental results show that SSL achieves on average 5.1× and 3.1× speedups of convolutional layer computation of AlexNet against CPU and GPU, respectively, with off-the-shelf libraries. These speedups are about twice speedups of non-structured sparsity; (3) regularize the DNN structure to improve classification accuracy. The results show that for CIFAR-10, regularization on layer depth can reduce 20 layers of a Deep Residual Network (ResNet) to 18 layers while improve the accuracy from 91.25% to 92.60%, which is still slightly higher than that of original ResNet with 32 layers. For AlexNet, structure regularization by SSL also reduces the error by ∼ 1%. Our source code can be found at https://github.com/wenwei202/caffe/tree/scnn