Robust prediction of citywide traffic flows at different time periods plays a crucial role in intelligent transportation systems. While previous work has made great efforts to model spatio-temporal correlations, existing methods still suffer from two key limitations: i) Most models collectively predict all regions' flows without accounting for spatial heterogeneity, i.e., different regions may have skewed traffic flow distributions. ii) These models fail to capture the temporal heterogeneity induced by time-varying traffic patterns, as they typically model temporal correlations with a shared parameterized space for all time periods. To tackle these challenges, we propose a novel Spatio-Temporal Self-Supervised Learning (ST-SSL) traffic prediction framework which enhances the traffic pattern representations to be reflective of both spatial and temporal heterogeneity, with auxiliary self-supervised learning paradigms. Specifically, our ST-SSL is built over an integrated module with temporal and spatial convolutions for encoding the information across space and time. To achieve the adaptive spatio-temporal self-supervised learning, our ST-SSL first performs the adaptive augmentation over the traffic flow graph data at both attribute- and structure-levels. On top of the augmented traffic graph, two SSL auxiliary tasks are constructed to supplement the main traffic prediction task with spatial and temporal heterogeneity-aware augmentation. Experiments on four benchmark datasets demonstrate that ST-SSL consistently outperforms various state-of-the-art baselines. Since spatio-temporal heterogeneity widely exists in practical datasets, the proposed framework may also cast light on other spatial-temporal applications. Model implementation is available at https://github.com/Echo-Ji/ST-SSL.

Despite the remarkable progress of image captioning, existing captioners typically lack the controllable capability to generate desired image captions, e.g., describing the image in a rough or detailed manner, in a factual or emotional view, etc. In this paper, we show that a unified model is qualified to perform well in diverse domains and freely switch among multiple styles. Such a controllable capability is achieved by embedding the prompt learning into the image captioning framework. To be specific, we design a set of prompts to fine-tune the pre-trained image captioner. These prompts allow the model to absorb stylized data from different domains for joint training, without performance degradation in each domain. Furthermore, we optimize the prompts with learnable vectors in the continuous word embedding space, avoiding the heuristic prompt engineering and meanwhile exhibiting superior performance. In the inference stage, our model is able to generate desired stylized captions by choosing the corresponding prompts. Extensive experiments verify the controllable capability of the proposed method. Notably, we achieve outstanding performance on two diverse image captioning benchmarks including COCO Karpathy split and TextCaps using a unified model.

A diffusion model learns to predict a vector field of gradients. We propose to apply chain rule on the learned gradients, and back-propagate the score of a diffusion model through the Jacobian of a differentiable renderer, which we instantiate to be a voxel radiance field. This setup aggregates 2D scores at multiple camera viewpoints into a 3D score, and repurposes a pretrained 2D model for 3D data generation. We identify a technical challenge of distribution mismatch that arises in this application, and propose a novel estimation mechanism to resolve it. We run our algorithm on several off-the-shelf diffusion image generative models, including the recently released Stable Diffusion trained on the large-scale LAION dataset.

Image super-resolution is a common task on mobile and IoT devices, where one often needs to upscale and enhance low-resolution images and video frames. While numerous solutions have been proposed for this problem in the past, they are usually not compatible with low-power mobile NPUs having many computational and memory constraints. In this Mobile AI challenge, we address this problem and propose the participants to design an efficient quantized image super-resolution solution that can demonstrate a real-time performance on mobile NPUs. The participants were provided with the DIV2K dataset and trained INT8 models to do a high-quality 3X image upscaling. The runtime of all models was evaluated on the Synaptics VS680 Smart Home board with a dedicated edge NPU capable of accelerating quantized neural networks. All proposed solutions are fully compatible with the above NPU, demonstrating an up to 60 FPS rate when reconstructing Full HD resolution images. A detailed description of all models developed in the challenge is provided in this paper.

Federated learning (FL) is a promising way to allow multiple data owners (clients) to collaboratively train machine learning models without compromising data privacy. Yet, existing FL solutions usually rely on a centralized aggregator for model weight aggregation, while assuming clients are honest. Even if data privacy can still be preserved, the problem of single-point failure and data poisoning attack from malicious clients remains unresolved. To tackle this challenge, we propose to use distributed ledger technology (DLT) to achieve FLock, a secure and reliable decentralized Federated Learning system built on blockchain. To guarantee model quality, we design a novel peer-to-peer (P2P) review and reward/slash mechanism to detect and deter malicious clients, powered by on-chain smart contracts. The reward/slash mechanism, in addition, serves as incentives for participants to honestly upload and review model parameters in the FLock system. FLock thus improves the performance and the robustness of FL systems in a fully P2P manner.

Dynamic interaction graphs have been widely adopted to model the evolution of user-item interactions over time. There are two crucial factors when modelling user preferences for link prediction in dynamic interaction graphs: 1) collaborative relationship among users and 2) user personalized interaction patterns. Existing methods often implicitly consider these two factors together, which may lead to noisy user modelling when the two factors diverge. In addition, they usually require time-consuming parameter learning with back-propagation, which is prohibitive for real-time user preference modelling. To this end, this paper proposes FreeGEM, a parameter-free dynamic graph embedding method for link prediction. Firstly, to take advantage of the collaborative relationships, we propose an incremental graph embedding engine to obtain user/item embeddings, which is an Online-Monitor-Offline architecture consisting of an Online module to approximately embed users/items over time, a Monitor module to estimate the approximation error in real time and an Offline module to calibrate the user/item embeddings when the online approximation errors exceed a threshold. Meanwhile, we integrate attribute information into the model, which enables FreeGEM to better model users belonging to some under represented groups. Secondly, we design a personalized dynamic interaction pattern modeller, which combines dynamic time decay with attention mechanism to model user short-term interests. Experimental results on two link prediction tasks show that FreeGEM can outperform the state-of-the-art methods in accuracy while achieving over 36X improvement in efficiency. All code and datasets can be found in https://github.com/FudanCISL/FreeGEM.

在本文中，我们解决了物体的主动机器人3D重建问题。特别是，我们研究了带有武器摄像机的移动机器人如何选择有利数量的视图来有效地恢复对象的3D形状。与现有的问题解决方案相反，我们利用了流行的神经辐射字段的对象表示，最近对各种计算机视觉任务显示了令人印象深刻的结果。但是，直接推荐使用这种表示形式的对象的显式3D几何细节，这并不是很直接的，这使得对密度3D重建的下一最佳视图选择问题具有挑战性。本文介绍了基于射线的容积不确定性估计器，该估计量沿对象隐式神经表示的每个光线沿每个射线的重量分布计算重量分布的熵。我们表明，考虑到提出的估计量的新观点，可以推断基础3D几何形状的不确定性。然后，我们提出了一个由基于射线的体积不确定性在基于神经辐射字段的表示中的指导下进行的最佳视图选择策略。令人鼓舞的关于合成和现实世界数据的实验结果表明，本文提出的方法可以使新的研究方向在机器人视觉应用中使用隐式的3D对象表示对次要的观察问题，从而将我们的方法与现有方法区分开依赖于显式3D几何建模的方法。

准确可靠的传感器校准对于在自主驾驶中融合激光雷达和惯性测量至关重要。本文提出了一种新型的3D-LIDAR和姿势传感器的新型三阶段外部校准方法，用于自主驾驶。第一阶段可以通过点云表面特征快速校准传感器之间的外部参数，以便可以将外部参数从大的初始误差范围缩小到很小的时间范围。第二阶段可以基于激光映射空间占用率进一步校准外部参数，同时消除运动失真。在最后阶段，校正了由自动驾驶汽车的平面运动引起的Z轴误差，并最终获得了精确的外部参数。具体而言，该方法利用了道路场景的自然特征，使其独立且易于在大规模条件下应用。现实世界数据集的实验结果证明了我们方法的可靠性和准确性。这些代码是在GitHub网站上开源的。据我们所知，这是第一个专门为自动驾驶设计的开源代码，用于校准激光雷达和姿势传感器外部参数。代码链接是https://github.com/opencalib/lidar2ins。

高性能的交通流量预测模型设计是一种智能运输系统的核心技术，是工业和学术社区的长期挑战，但仍然具有挑战性。物理原理和数据驱动模型之间缺乏整合是限制该领域发展的重要原因。在文献中，基于物理学的方法通常可以清楚地解释交通流系统的动态过程，但准确性有限，而数据驱动的方法，尤其是使用黑色盒子结构的深度学习，可以提高性能，但不能由于缺乏合理的身体依据，因此要完全信任。为了弥合纯粹数据驱动和物理驱动的方法之间的差距，我们提出了一个物理学引导的深度学习模型，名为时空微分方程网络（STDEN），该模型将交通流动器的物理机理投入到深度神经网络框架中。具体而言，我们假设道路网络上的交通流量是由潜在势能场驱动的（例如水流是由重力场驱动的），并将势能场的时空动态过程作为微分方程网络进行建模。 Stden吸收了数据驱动模型的性能优势和基于物理模型的可解释性，因此被命名为物理指导的预测模型。北京三个现实世界流量数据集的实验表明，我们的模型的表现优于最先进的基线。案例研究进一步验证了stden可以捕获城市交通机制，并具有物理含义的准确预测。提出的微分方程网络建模的框架也可能会阐明其他类似的应用程序。

本文旨在探讨如何合成对其进行训练的现有视频脱毛模型的近距离模糊，可以很好地推广到现实世界中的模糊视频。近年来，基于深度学习的方法已在视频Deblurring任务上取得了希望的成功。但是，对现有合成数据集培训的模型仍然遭受了与现实世界中的模糊场景的概括问题。造成故障的因素仍然未知。因此，我们重新审视经典的模糊综合管道，并找出可能的原因，包括拍摄参数，模糊形成空间和图像信号处理器〜（ISP）。为了分析这些潜在因素的效果，我们首先收集一个超高帧速率（940 fps）原始视频数据集作为数据基础，以综合各种模糊。然后，我们提出了一种新颖的现实模糊合成管道，该管道通过利用模糊形成线索称为原始爆炸。通过大量实验，我们证明了在原始空间中的合成模糊并采用与现实世界测试数据相同的ISP可以有效消除合成数据的负面影响。此外，合成的模糊视频的拍摄参数，例如，曝光时间和框架速率在改善脱毛模型的性能中起着重要作用。令人印象深刻的是，与在现有合成模糊数据集中训练的训练的模型合成的模糊数据训练的模型可以获得超过5DB PSNR的增益。我们认为，新颖的现实合成管道和相应的原始视频数据集可以帮助社区轻松构建自定义的Blur数据集，以改善现实世界的视频DeBlurring性能，而不是费力地收集真实的数据对。