点云压缩（PCC）是各种3-D应用程序的关键推动器，这是由于点云格式的通用性。理想情况下，3D点云努力描绘了连续的对象/场景表面。实际上，作为一组离散样本，点云是局部断开连接并稀疏分布的。这种稀疏的性质阻碍了在压缩点之间发现局部相关性的发现。通过分形维度的分析，我们提出了一种异质方法，并深入学习有损耗的点云几何压缩。在压缩输入的粗表示的基础层的顶部上，增强层的设计旨在应对具有挑战性的几何残差/详细信息。具体而言，应用基于点的网络将不稳定的本地详细信息转换为位于粗点云上的潜在特征。然后启动了在粗点云上运行的稀疏卷积神经网络。它利用粗糙几何形状的连续性/平滑度来压缩潜在特征，作为增强的位流，极大地使重建质量受益。当此位流不可用时，例如，由于数据包丢失，我们支持具有相同体系结构的跳过模式，该模式直接从粗点云中生成几何细节。对密度和稀疏点云的实验证明了我们的提案实现的最新压缩性能。我们的代码可在https://github.com/interdigitalinc/grasp-net上找到。

3D点云通常由一个或多个观点处由传感器获取的深度测量构成。测量值遭受量化和噪声损坏。为了提高质量，以前的作品在将不完美深度数据投射到3D空间之后，将点云\ Textit {a postiriori}代名。相反，在合成3D点云之前，我们在感测图像\ Texit {a先验}上直接增强深度测量。通过增强物理传感过程附近，在后续处理步骤模糊测量误差之前，我们将我们的优化定制到我们的深度形成模型。具体而言，我们将深度形成为信号相关噪声添加和非均匀日志量化的组合过程。使用来自实际深度传感器的收集的经验数据验证设计的模型（配有参数）。为了在深度图像中增强每个像素行，我们首先通过特征图学习将可用行像素之间的视图帧内相似性编码为边缘权重。接下来我们通过观点映射和稀疏线性插值建立与另一个整流的深度图像的视图间相似性。这导致最大的后验（MAP）图滤波物镜，其凸显和可微分。我们使用加速梯度下降（AGD）有效地优化目标，其中最佳步长通过Gershgorin圆定理（GCT）近似。实验表明，我们的方法在两个既定点云质量指标中显着优于最近的近期云去噪方案和最先进的图像去噪方案。

场景流程描绘了3D场景的动态，这对于传统上，从诸如自主驾驶，机器人导航，AR / VR等的各种应用来说至关重要。从密集/常规RGB视频帧估计场景流。随着深度感测技术的发展，通过点云可获得精确的3D测量，这在3D场景流中引发了新的研究。然而，由于典型点云采样模式中的稀缺性和不规则性，从点云中提取场景流量仍然具有挑战性。与不规则采样相关的一个主要问题被识别为点设置抽象/特征提取期间的随机性 - 许多流程估计场景中的基本进程。因此，提出了一种注意力（SA ^ 2）层的新型空间抽象，以减轻不稳定的抽象问题。此外，提出了一种注意力（TA ^ 2）层的时间抽象来纠正时间域中的注意力，导致运动中的运动缩放在更大范围内。广泛的分析和实验验证了我们方法的动机和显着性能收益，与空间 - 时间注意（Festa）称为流量估计，与场景流估计的几个最先进的基准相比。

We propose a distributionally robust return-risk model for Markov decision processes (MDPs) under risk and reward ambiguity. The proposed model optimizes the weighted average of mean and percentile performances, and it covers the distributionally robust MDPs and the distributionally robust chance-constrained MDPs (both under reward ambiguity) as special cases. By considering that the unknown reward distribution lies in a Wasserstein ambiguity set, we derive the tractable reformulation for our model. In particular, we show that that the return-risk model can also account for risk from uncertain transition kernel when one only seeks deterministic policies, and that a distributionally robust MDP under the percentile criterion can be reformulated as its nominal counterpart at an adjusted risk level. A scalable first-order algorithm is designed to solve large-scale problems, and we demonstrate the advantages of our proposed model and algorithm through numerical experiments.

Temporal sentence grounding (TSG) aims to identify the temporal boundary of a specific segment from an untrimmed video by a sentence query. All existing works first utilize a sparse sampling strategy to extract a fixed number of video frames and then conduct multi-modal interactions with query sentence for reasoning. However, we argue that these methods have overlooked two indispensable issues: 1) Boundary-bias: The annotated target segment generally refers to two specific frames as corresponding start and end timestamps. The video downsampling process may lose these two frames and take the adjacent irrelevant frames as new boundaries. 2) Reasoning-bias: Such incorrect new boundary frames also lead to the reasoning bias during frame-query interaction, reducing the generalization ability of model. To alleviate above limitations, in this paper, we propose a novel Siamese Sampling and Reasoning Network (SSRN) for TSG, which introduces a siamese sampling mechanism to generate additional contextual frames to enrich and refine the new boundaries. Specifically, a reasoning strategy is developed to learn the inter-relationship among these frames and generate soft labels on boundaries for more accurate frame-query reasoning. Such mechanism is also able to supplement the absent consecutive visual semantics to the sampled sparse frames for fine-grained activity understanding. Extensive experiments demonstrate the effectiveness of SSRN on three challenging datasets.

Forecasts by the European Centre for Medium-Range Weather Forecasts (ECMWF; EC for short) can provide a basis for the establishment of maritime-disaster warning systems, but they contain some systematic biases.The fifth-generation EC atmospheric reanalysis (ERA5) data have high accuracy, but are delayed by about 5 days. To overcome this issue, a spatiotemporal deep-learning method could be used for nonlinear mapping between EC and ERA5 data, which would improve the quality of EC wind forecast data in real time. In this study, we developed the Multi-Task-Double Encoder Trajectory Gated Recurrent Unit (MT-DETrajGRU) model, which uses an improved double-encoder forecaster architecture to model the spatiotemporal sequence of the U and V components of the wind field; we designed a multi-task learning loss function to correct wind speed and wind direction simultaneously using only one model. The study area was the western North Pacific (WNP), and real-time rolling bias corrections were made for 10-day wind-field forecasts released by the EC between December 2020 and November 2021, divided into four seasons. Compared with the original EC forecasts, after correction using the MT-DETrajGRU model the wind speed and wind direction biases in the four seasons were reduced by 8-11% and 9-14%, respectively. In addition, the proposed method modelled the data uniformly under different weather conditions. The correction performance under normal and typhoon conditions was comparable, indicating that the data-driven mode constructed here is robust and generalizable.

Despite a sea of interpretability methods that can produce plausible explanations, the field has also empirically seen many failure cases of such methods. In light of these results, it remains unclear for practitioners how to use these methods and choose between them in a principled way. In this paper, we show that for even moderately rich model classes (easily satisfied by neural networks), any feature attribution method that is complete and linear--for example, Integrated Gradients and SHAP--can provably fail to improve on random guessing for inferring model behaviour. Our results apply to common end-tasks such as identifying local model behaviour, spurious feature identification, and algorithmic recourse. One takeaway from our work is the importance of concretely defining end-tasks. In particular, we show that once such an end-task is defined, a simple and direct approach of repeated model evaluations can outperform many other complex feature attribution methods.

Visual language such as charts and plots is ubiquitous in the human world. Comprehending plots and charts requires strong reasoning skills. Prior state-of-the-art (SOTA) models require at least tens of thousands of training examples and their reasoning capabilities are still much limited, especially on complex human-written queries. This paper presents the first one-shot solution to visual language reasoning. We decompose the challenge of visual language reasoning into two steps: (1) plot-to-text translation, and (2) reasoning over the translated text. The key in this method is a modality conversion module, named as DePlot, which translates the image of a plot or chart to a linearized table. The output of DePlot can then be directly used to prompt a pretrained large language model (LLM), exploiting the few-shot reasoning capabilities of LLMs. To obtain DePlot, we standardize the plot-to-table task by establishing unified task formats and metrics, and train DePlot end-to-end on this task. DePlot can then be used off-the-shelf together with LLMs in a plug-and-play fashion. Compared with a SOTA model finetuned on more than >28k data points, DePlot+LLM with just one-shot prompting achieves a 24.0% improvement over finetuned SOTA on human-written queries from the task of chart QA.

Robust Markov decision processes (RMDPs) are promising models that provide reliable policies under ambiguities in model parameters. As opposed to nominal Markov decision processes (MDPs), however, the state-of-the-art solution methods for RMDPs are limited to value-based methods, such as value iteration and policy iteration. This paper proposes Double-Loop Robust Policy Gradient (DRPG), the first generic policy gradient method for RMDPs with a global convergence guarantee in tabular problems. Unlike value-based methods, DRPG does not rely on dynamic programming techniques. In particular, the inner-loop robust policy evaluation problem is solved via projected gradient descent. Finally, our experimental results demonstrate the performance of our algorithm and verify our theoretical guarantees.

Visual language data such as plots, charts, and infographics are ubiquitous in the human world. However, state-of-the-art vision-language models do not perform well on these data. We propose MatCha (Math reasoning and Chart derendering pretraining) to enhance visual language models' capabilities in jointly modeling charts/plots and language data. Specifically, we propose several pretraining tasks that cover plot deconstruction and numerical reasoning which are the key capabilities in visual language modeling. We perform the MatCha pretraining starting from Pix2Struct, a recently proposed image-to-text visual language model. On standard benchmarks such as PlotQA and ChartQA, the MatCha model outperforms state-of-the-art methods by as much as nearly 20%. We also examine how well MatCha pretraining transfers to domains such as screenshots, textbook diagrams, and document figures and observe overall improvement, verifying the usefulness of MatCha pretraining on broader visual language tasks.