The number of international benchmarking competitions is steadily increasing in various fields of machine learning (ML) research and practice. So far, however, little is known about the common practice as well as bottlenecks faced by the community in tackling the research questions posed. To shed light on the status quo of algorithm development in the specific field of biomedical imaging analysis, we designed an international survey that was issued to all participants of challenges conducted in conjunction with the IEEE ISBI 2021 and MICCAI 2021 conferences (80 competitions in total). The survey covered participants' expertise and working environments, their chosen strategies, as well as algorithm characteristics. A median of 72% challenge participants took part in the survey. According to our results, knowledge exchange was the primary incentive (70%) for participation, while the reception of prize money played only a minor role (16%). While a median of 80 working hours was spent on method development, a large portion of participants stated that they did not have enough time for method development (32%). 25% perceived the infrastructure to be a bottleneck. Overall, 94% of all solutions were deep learning-based. Of these, 84% were based on standard architectures. 43% of the respondents reported that the data samples (e.g., images) were too large to be processed at once. This was most commonly addressed by patch-based training (69%), downsampling (37%), and solving 3D analysis tasks as a series of 2D tasks. K-fold cross-validation on the training set was performed by only 37% of the participants and only 50% of the participants performed ensembling based on multiple identical models (61%) or heterogeneous models (39%). 48% of the respondents applied postprocessing steps.

来自计算机断层扫描血管造影（CTA）的肾脏结构分割对于许多计算机辅助的肾脏癌治疗应用至关重要。肾脏解析〜（KIPA 2022）挑战旨在建立细粒度的多结构数据集并改善多个肾脏结构的分割。最近，U-NET主导了医疗图像分割。在KIPA挑战中，我们评估了几个U-NET变体，并选择了最终提交的最佳模型。

我们建议对视觉模型预处理的基于利润的损失，以鼓励基于梯度的解释，这些解释与区域级注释一致。我们将该目标称为注意面罩的一致性（AMC），并证明它与依赖于区域级注释的模型相比，它产生了卓越的视觉接地性能，以显式训练对象检测器，例如更快的R-CNN。 AMC通过鼓励基于梯度的解释掩盖来工作，该掩盖的注意力分数主要集中在包含这种注释的图像的注释区域中。尤其是，在标准视觉建模目标之上接受AMC训练的模型在FlickR30K视觉接地基准中获得了86.59％的最新精度，与最佳先前模型相比，绝对改善了5.48％。我们的方法在既定的基准中都表现出表达理解，并通过设计基于梯度的解释来更好地与人类注释保持一致，从而提供了极大的表现。

强化学习（RL）涉及在未知系统中执行探索性动作。这可以将学习代理放在危险且潜在的灾难性系统中。当前在RL中解决安全学习的方法同时权衡了安全探索和任务实现。在本文中，我们介绍了新一代的RL求解器，这些求解器学会最大程度地减少安全性违规行为，同时在安全政策可以容忍的范围内最大化任务奖励。我们的方法引入了一个新型的两人框架，用于安全RL，称为分配探索安全培训算法（DESTA）。 DESTA的核心是两种自适应代理之间的游戏：安全代理，其任务是最大程度地减少安全违规行为和任务代理，其目标是最大程度地提高环境奖励。具体而言，安全代理可以在任何给定点有选择地控制系统，以防止任务代理在任何其他州自由执行其策略时违反安全性。该框架使安全代理能够学会在培训和测试时间中最大程度地减少未来安全违规行为的某些行动，而任务代理人执行的动作可以最大程度地提高其他任何地方的任务绩效。从理论上讲，我们证明DESTA会汇合到稳定的点，从而最大程度地违反了对预验证的政策的行为。从经验上讲，我们表明了DESTA提高现有政策安全性的能力，其次，当对任务代理和安全代理人同时培训时，构建安全的RL政策。我们展示了DESTA在Lunar Lander和Openai Gym的Frozen Lake中的领先RL方法的出色表现。

To date, little attention has been given to multi-view 3D human mesh estimation, despite real-life applicability (e.g., motion capture, sport analysis) and robustness to single-view ambiguities. Existing solutions typically suffer from poor generalization performance to new settings, largely due to the limited diversity of image-mesh pairs in multi-view training data. To address this shortcoming, people have explored the use of synthetic images. But besides the usual impact of visual gap between rendered and target data, synthetic-data-driven multi-view estimators also suffer from overfitting to the camera viewpoint distribution sampled during training which usually differs from real-world distributions. Tackling both challenges, we propose a novel simulation-based training pipeline for multi-view human mesh recovery, which (a) relies on intermediate 2D representations which are more robust to synthetic-to-real domain gap; (b) leverages learnable calibration and triangulation to adapt to more diversified camera setups; and (c) progressively aggregates multi-view information in a canonical 3D space to remove ambiguities in 2D representations. Through extensive benchmarking, we demonstrate the superiority of the proposed solution especially for unseen in-the-wild scenarios.

The capture and animation of human hair are two of the major challenges in the creation of realistic avatars for the virtual reality. Both problems are highly challenging, because hair has complex geometry and appearance, as well as exhibits challenging motion. In this paper, we present a two-stage approach that models hair independently from the head to address these challenges in a data-driven manner. The first stage, state compression, learns a low-dimensional latent space of 3D hair states containing motion and appearance, via a novel autoencoder-as-a-tracker strategy. To better disentangle the hair and head in appearance learning, we employ multi-view hair segmentation masks in combination with a differentiable volumetric renderer. The second stage learns a novel hair dynamics model that performs temporal hair transfer based on the discovered latent codes. To enforce higher stability while driving our dynamics model, we employ the 3D point-cloud autoencoder from the compression stage for de-noising of the hair state. Our model outperforms the state of the art in novel view synthesis and is capable of creating novel hair animations without having to rely on hair observations as a driving signal.

The explosive growth of dynamic and heterogeneous data traffic brings great challenges for 5G and beyond mobile networks. To enhance the network capacity and reliability, we propose a learning-based dynamic time-frequency division duplexing (D-TFDD) scheme that adaptively allocates the uplink and downlink time-frequency resources of base stations (BSs) to meet the asymmetric and heterogeneous traffic demands while alleviating the inter-cell interference. We formulate the problem as a decentralized partially observable Markov decision process (Dec-POMDP) that maximizes the long-term expected sum rate under the users' packet dropping ratio constraints. In order to jointly optimize the global resources in a decentralized manner, we propose a federated reinforcement learning (RL) algorithm named federated Wolpertinger deep deterministic policy gradient (FWDDPG) algorithm. The BSs decide their local time-frequency configurations through RL algorithms and achieve global training via exchanging local RL models with their neighbors under a decentralized federated learning framework. Specifically, to deal with the large-scale discrete action space of each BS, we adopt a DDPG-based algorithm to generate actions in a continuous space, and then utilize Wolpertinger policy to reduce the mapping errors from continuous action space back to discrete action space. Simulation results demonstrate the superiority of our proposed algorithm to benchmark algorithms with respect to system sum rate.

了解动态场景中的3D运动对于许多视觉应用至关重要。最近的进步主要集中在估计人类等某些特定元素的活动上。在本文中，我们利用神经运动场来估计多视图设置中所有点的运动。由于颜色相似的点和与时变颜色的点的歧义，从动态场景中对动态场景进行建模运动是具有挑战性的。我们建议将估计运动的正规化为可预测。如果已知来自以前的帧的运动，那么在不久的将来的运动应该是可以预测的。因此，我们通过首先调节潜在嵌入的估计运动来引入可预测性正则化，然后通过采用预测网络来在嵌入式上执行可预测性。所提出的框架pref（可预测性正则化字段）比基于最先进的神经运动场的动态场景表示方法在PAR或更好的结果上取得了更好的成绩，同时不需要对场景的先验知识。

联合学习（FL）是一种机器学习范式，本地节点在培训数据保持分散时进行了协作训练中心模型。现有的FL方法通常共享模型参数或采用共同依据来解决不平衡数据分布的问题。但是，他们患有沟通瓶颈。更重要的是，他们有隐私泄漏的风险。在这项工作中，我们在FL框架中开发了一种隐私和沟通高效方法，并使用未标记的跨域公共数据进行单次离线知识蒸馏。我们提出了一个量化的和嘈杂的本地预测合奏，从经过全面训练的本地模型中，以确保更强的隐私保证而无需牺牲准确性。基于有关图像分类和文本分类任务的广泛实验，我们表明，我们的隐私方法优于基线FL算法，其精度和沟通效率都具有出色的性能。

全面监督的人类网格恢复方法是渴望数据的，由于3D规定基准数据集的可用性有限和多样性，因此具有较差的概括性。使用合成数据驱动的训练范例，已经从合成配对的2D表示（例如2D关键点和分段掩码）和3D网格中训练了模型的最新进展，其中已使用合成数据驱动的训练范例和3D网格进行了训练。但是，由于合成训练数据和实际测试数据之间的域间隙很难解决2D密集表示，因此很少探索合成密集的对应图（即IUV）。为了减轻IUV上的这个领域差距，我们提出了使用可靠但稀疏表示的互补信息（2D关键点）提出的交叉代理对齐。具体而言，初始网格估计和两个2D表示之间的比对误差将转发为回归器，并在以下网格回归中动态校正。这种适应性的交叉代理对准明确地从偏差和捕获互补信息中学习：从稀疏的表示和浓郁的浓度中的稳健性。我们对多个标准基准数据集进行了广泛的实验，并展示了竞争结果，帮助减少在人类网格估计中生产最新模型所需的注释工作。