光流估计的最新方法取决于深度学习，这需要复杂的顺序训练方案才能在现实世界中达到最佳性能。在这项工作中，我们介绍了组合深网，该网络明确利用了传统方法中使用的亮度恒定（BC）模型。由于卑诗省是在几种情况下违反的一个近似物理模型，因此我们建议训练一个与数据驱动网络相辅相成的物理约束网络。我们在物理先验和数据驱动的补体之间引入了独特而有意义的流动分解，包括对BC模型的不确定性量化。我们得出了一个联合培训计划，用于学习分解的不同组成部分，以确保在受监督的情况下，但在半监督的环境中进行最佳合作。实验表明，组合可以改善对最先进的监督网络的性能，例如木筏在几个基准测试中达到最先进的结果。我们强调组合如何利用BC模型并适应其局限性。最后，我们表明我们的半监督方法可以显着简化训练程序。

无监督的对光流计算的深度学习取得了令人鼓舞的结果。大多数现有的基于深网的方法都依赖图像亮度一致性和局部平滑度约束来训练网络。他们的性能在发生重复纹理或遮挡的区域降低。在本文中，我们提出了深层的外两极流，这是一种无监督的光流方法，将全局几何约束结合到网络学习中。特别是，我们研究了多种方式在流量估计中强制执行外两极约束。为了减轻在可能存在多个动作的动态场景中遇到的“鸡肉和蛋”类型的问题，我们提出了一个低级别的约束以及对培训的订婚结合的约束。各种基准测试数据集的实验结果表明，与监督方法相比，我们的方法实现了竞争性能，并且优于最先进的无监督深度学习方法。

光流CNNS的训练管道由合成数据集的预处理阶段组成，然后在目标数据集上进行微调阶段。但是，从目标视频中获得地面真理需要巨大的努力。本文提出了一种实用的微调方法，将预处理的模型调整到没有地面真相流的目标数据集中，但尚未进行广泛探讨。具体而言，我们为自我划分的流程主管提出了一个流程主管，其中包括参数分离和学生量连接。该设计的目的是稳定的收敛性和更好的准确性，而在微调任务上是不稳定的传统自我实施方法。实验结果表明，与半监督学习的不同自学方法相比，我们方法的有效性。此外，我们通过利用其他未标记的数据集来实现对Sintel和Kitti基准测试的最先进的光流模型的有意义的改进。代码可在https://github.com/iwbn/flow-supervisor上找到。

与无监督培训相比，对光流预测因子的监督培训通常会产生更好的准确性。但是，改进的性能通常以较高的注释成本。半监督的培训与注释成本相比，准确性的准确性。我们使用一种简单而有效的半监督训练方法来表明，即使一小部分标签也可以通过无监督的训练来提高流量准确性。此外，我们提出了基于简单启发式方法的主动学习方法，以进一步减少实现相同目标准确性所需的标签数量。我们对合成和真实光流数据集的实验表明，我们的半监督网络通常需要大约50％的标签才能达到接近全标签的精度，而在Sintel上有效学习只有20％左右。我们还分析并展示了有关可能影响主动学习绩效的因素的见解。代码可在https://github.com/duke-vision/optical-flow-active-learning-release上找到。

自我监督的单眼深度估计使机器人能够从原始视频流中学习3D感知。假设世界主要是静态的，这种可扩展的方法利用了投射的几何形状和自我运动来通过视图综合学习。在自主驾驶和人类机器人相互作用中常见的动态场景违反了这一假设。因此，它们需要明确建模动态对象，例如通过估计像素3D运动，即场景流。但是，同时对深度和场景流的自我监督学习是不适合的，因为有许多无限的组合导致相同的3D点。在本文中，我们提出了一种草稿，这是一种通过将合成数据与几何自学意识相结合的新方法，能够共同学习深度，光流和场景流。在木筏架构的基础上，我们将光流作为中间任务，以通过三角剖分来引导深度和场景流量学习。我们的算法还利用任务之间的时间和几何一致性损失来改善多任务学习。我们的草案在标准Kitti基准的自我监督的单眼环境中，同时在所有三个任务中建立了新的最新技术状态。项目页面：https：//sites.google.com/tri.global/draft。

Recent works have shown that optical flow can be learned by deep networks from unlabelled image pairs based on brightness constancy assumption and smoothness prior. Current approaches additionally impose an augmentation regularization term for continual self-supervision, which has been proved to be effective on difficult matching regions. However, this method also amplify the inevitable mismatch in unsupervised setting, blocking the learning process towards optimal solution. To break the dilemma, we propose a novel mutual distillation framework to transfer reliable knowledge back and forth between the teacher and student networks for alternate improvement. Concretely, taking estimation of off-the-shelf unsupervised approach as pseudo labels, our insight locates at defining a confidence selection mechanism to extract relative good matches, and then add diverse data augmentation for distilling adequate and reliable knowledge from teacher to student. Thanks to the decouple nature of our method, we can choose a stronger student architecture for sufficient learning. Finally, better student prediction is adopted to transfer knowledge back to the efficient teacher without additional costs in real deployment. Rather than formulating it as a supervised task, we find that introducing an extra unsupervised term for multi-target learning achieves best final results. Extensive experiments show that our approach, termed MDFlow, achieves state-of-the-art real-time accuracy and generalization ability on challenging benchmarks. Code is available at https://github.com/ltkong218/MDFlow.

We present a compact but effective CNN model for optical flow, called PWC-Net. PWC-Net has been designed according to simple and well-established principles: pyramidal processing, warping, and the use of a cost volume. Cast in a learnable feature pyramid, PWC-Net uses the current optical flow estimate to warp the CNN features of the second image. It then uses the warped features and features of the first image to construct a cost volume, which is processed by a CNN to estimate the optical flow. PWC-Net is 17 times smaller in size and easier to train than the recent FlowNet2 model. Moreover, it outperforms all published optical flow methods on the MPI Sintel final pass and KITTI 2015 benchmarks, running at about 35 fps on Sintel resolution (1024×436) images. Our models are available on https://github.com/NVlabs/PWC-Net.

Recently, AutoFlow has shown promising results on learning a training set for optical flow, but requires ground truth labels in the target domain to compute its search metric. Observing a strong correlation between the ground truth search metric and self-supervised losses, we introduce self-supervised AutoFlow to handle real-world videos without ground truth labels. Using self-supervised loss as the search metric, our self-supervised AutoFlow performs on par with AutoFlow on Sintel and KITTI where ground truth is available, and performs better on the real-world DAVIS dataset. We further explore using self-supervised AutoFlow in the (semi-)supervised setting and obtain competitive results against the state of the art.

We propose GeoNet, a jointly unsupervised learning framework for monocular depth, optical flow and egomotion estimation from videos. The three components are coupled by the nature of 3D scene geometry, jointly learned by our framework in an end-to-end manner. Specifically, geometric relationships are extracted over the predictions of individual modules and then combined as an image reconstruction loss, reasoning about static and dynamic scene parts separately. Furthermore, we propose an adaptive geometric consistency loss to increase robustness towards outliers and non-Lambertian regions, which resolves occlusions and texture ambiguities effectively. Experimentation on the KITTI driving dataset reveals that our scheme achieves state-of-the-art results in all of the three tasks, performing better than previously unsupervised methods and comparably with supervised ones.

在本文中，通过以自我监督的方式将基于几何的方法纳入深度学习架构来实现强大的视觉测量（VO）的基本问题。通常，基于纯几何的算法与特征点提取和匹配中的深度学习不那么稳健，但由于其成熟的几何理论，在自我运动估计中表现良好。在这项工作中，首先提出了一种新颖的光学流量网络（PANET）内置于位置感知机构。然后，提出了一种在没有典型网络的情况下共同估计深度，光学流动和自我运动来学习自我运动的新系统。所提出的系统的关键组件是一种改进的束调节模块，其包含多个采样，初始化的自我运动，动态阻尼因子调整和Jacobi矩阵加权。另外，新颖的相对光度损耗函数先进以提高深度估计精度。该实验表明，所提出的系统在基于基于基于基于基于基于基于基于学习的基于学习的方法之间的深度，流量和VO估计方面不仅优于其他最先进的方法，而且与几何形状相比，也显着提高了鲁棒性 - 基于，基于学习和混合VO系统。进一步的实验表明，我们的模型在挑战室内（TMU-RGBD）和室外（KAIST）场景中实现了出色的泛化能力和性能。

Synthetic datasets are often used to pretrain end-to-end optical flow networks, due to the lack of a large amount of labeled, real-scene data. But major drops in accuracy occur when moving from synthetic to real scenes. How do we better transfer the knowledge learned from synthetic to real domains? To this end, we propose CLIP-FLow, a semi-supervised iterative pseudo-labeling framework to transfer the pretraining knowledge to the target real domain. We leverage large-scale, unlabeled real data to facilitate transfer learning with the supervision of iteratively updated pseudo-ground truth labels, bridging the domain gap between the synthetic and the real. In addition, we propose a contrastive flow loss on reference features and the warped features by pseudo ground truth flows, to further boost the accurate matching and dampen the mismatching due to motion, occlusion, or noisy pseudo labels. We adopt RAFT as the backbone and obtain an F1-all error of 4.11%, i.e. a 19% error reduction from RAFT (5.10%) and ranking 2$^{nd}$ place at submission on the KITTI 2015 benchmark. Our framework can also be extended to other models, e.g. CRAFT, reducing the F1-all error from 4.79% to 4.66% on KITTI 2015 benchmark.

We introduce Recurrent All-Pairs Field Transforms (RAFT), a new deep network architecture for optical flow. RAFT extracts perpixel features, builds multi-scale 4D correlation volumes for all pairs of pixels, and iteratively updates a flow field through a recurrent unit that performs lookups on the correlation volumes. RAFT achieves stateof-the-art performance. On KITTI, RAFT achieves an F1-all error of 5.10%, a 16% error reduction from the best published result (6.10%). On Sintel (final pass), RAFT obtains an end-point-error of 2.855 pixels, a 30% error reduction from the best published result (4.098 pixels). In addition, RAFT has strong cross-dataset generalization as well as high efficiency in inference time, training speed, and parameter count. Code is available at https://github.com/princeton-vl/RAFT.

We learn to compute optical flow by combining a classical spatial-pyramid formulation with deep learning. This estimates large motions in a coarse-to-fine approach by warping one image of a pair at each pyramid level by the current flow estimate and computing an update to the flow. Instead of the standard minimization of an objective function at each pyramid level, we train one deep network per level to compute the flow update. Unlike the recent FlowNet approach, the networks do not need to deal with large motions; these are dealt with by the pyramid. This has several advantages. First, our Spatial Pyramid Network (SPyNet) is much simpler and 96% smaller than FlowNet in terms of model parameters. This makes it more efficient and appropriate for embedded applications. Second, since the flow at each pyramid level is small (< 1 pixel), a convolutional approach applied to pairs of warped images is appropriate. Third, unlike FlowNet, the learned convolution filters appear similar to classical spatio-temporal filters, giving insight into the method and how to improve it. Our results are more accurate than FlowNet on most standard benchmarks, suggesting a new direction of combining classical flow methods with deep learning.1 This, of course, has well-known limitations, which we discuss later.

在本文中，我们提出了USEGSCENE，该框架用于使用卷积神经网络对立体声相机图像的深度，光流和自我感动的无监督学习。我们的框架利用语义信息来改善深度和光流图的正则化，多模式融合和遮挡填充考虑动态刚性对象运动作为独立的SE（3）转换。此外，我们与纯照相匹配匹配互补，我们提出了连续图像之间语义特征，像素类别和对象实例边界的匹配。与以前的方法相反，我们提出了一个网络体系结构，该网络体系结构可以使用共享编码器共同预测所有输出，并允许在任务域上传递信息，例如，光流的预测可以从深度的预测中受益。此外，我们明确地了解网络内部的深度和光流遮挡图，这些图被利用，以改善这些区域的预测。我们在流行的Kitti数据集上介绍了结果，并表明我们的方法以大幅度的优于其他方法。

近年来，深度神经网络表明它们在解决包括场景流预测在内的许多计算机视觉任务方面具有超越能力。但是，大多数进步取决于每个像素地面真相注释的大量致密性，这对于现实生活中的情况很难获得。因此，通常依靠合成数据进行监督，从而导致培训和测试数据之间的表示差距。即使有大量未标记的现实世界数据可用，但对于场景流预测的自我监督方法还是很大的缺乏。因此，我们探讨了基于人口普查转换和遮挡意识到的双向位移的自我监督损失的扩展，以解决场景流动预测问题。关于KITTI场景基准，我们的方法优于相同网络的相应监督预培训，并显示出改善的概括功能，同时达到更快的收敛速度。

光学流量估计是视频分析领域的一个重要而有挑战性问题。卷积神经网络的不同语义级别/层的特征可以提供不同粒度的信息。为了利用如此灵活和全面的信息，我们提出了一个半监督的特征金字塔形相关和残余重建网络（FPCR-Net），用于框架对的光学流量估计。它由两个主要模块组成：金字塔相关映射和剩余重建。金字塔相关映射模块利用全局/本地补丁的多尺度相关性来通过聚合不同尺度的特征来形成多级成本卷。剩余重建模块旨在重建每个阶段中更精细的光学流的子带高频残差。基于金字塔相关映射，我们进一步提出了相关 - 扭曲 - 归一化（CWN）模块，以有效地利用相关性依赖性。实验结果表明，该方案在针对竞争基线方法的平均终点误差（AEE）方面，实现了最先进的性能，改善了0.80,1.15和0.10 - Flownet2，LiteFlowNet和PWC-Net Sintel DataSet的最终通过。

Photometric differences are widely used as supervision signals to train neural networks for estimating depth and camera pose from unlabeled monocular videos. However, this approach is detrimental for model optimization because occlusions and moving objects in a scene violate the underlying static scenario assumption. In addition, pixels in textureless regions or less discriminative pixels hinder model training. To solve these problems, in this paper, we deal with moving objects and occlusions utilizing the difference of the flow fields and depth structure generated by affine transformation and view synthesis, respectively. Secondly, we mitigate the effect of textureless regions on model optimization by measuring differences between features with more semantic and contextual information without adding networks. In addition, although the bidirectionality component is used in each sub-objective function, a pair of images are reasoned about only once, which helps reduce overhead. Extensive experiments and visual analysis demonstrate the effectiveness of the proposed method, which outperform existing state-of-the-art self-supervised methods under the same conditions and without introducing additional auxiliary information.

现有的基于深度学习的无监督视频对象分割方法仍依靠地面真实的细分面具来训练。在这种情况下令人未知的意味着在推理期间没有使用注释帧。由于获得真实图像场景的地面真实的细分掩码是一种艰苦的任务，我们想到了一个简单的框架，即占主导地位的移动对象分割，既不需要注释数据训练，也不依赖于显着的电视或预先训练的光流程图。灵感来自分层图像表示，我们根据仿射参数运动引入对像素区域进行分组的技术。这使我们的网络能够仅使用RGB图像对为培训和推理的输入来学习主要前景对象的分割。我们使用新的MOVERCARS DataSet为这项新颖任务建立了基线，并对最近的方法表现出竞争性能，这些方法需要培训带有注释面具的最新方法。

We address the unsupervised learning of several interconnected problems in low-level vision: single view depth prediction, camera motion estimation, optical flow, and segmentation of a video into the static scene and moving regions. Our key insight is that these four fundamental vision problems are coupled through geometric constraints. Consequently, learning to solve them together simplifies the problem because the solutions can reinforce each other. We go beyond previous work by exploiting geometry more explicitly and segmenting the scene into static and moving regions. To that end, we introduce Competitive Collaboration, a framework that facilitates the coordinated training of multiple specialized neural networks to solve complex problems. Competitive Collaboration works much like expectation-maximization, but with neural networks that act as both competitors to explain pixels that correspond to static or moving regions, and as collaborators through a moderator that assigns pixels to be either static or independently moving. Our novel method integrates all these problems in a common framework and simultaneously reasons about the segmentation of the scene into moving objects and the static background, the camera motion, depth of the static scene structure, and the optical flow of moving objects. Our model is trained without any supervision and achieves state-of-the-art performance among joint unsupervised methods on all sub-problems. .

从视频中获得地面真相标签很具有挑战性，因为在像素流标签的手动注释非常昂贵且费力。此外，现有的方法试图将合成数据集的训练模型调整到真实的视频中，该视频不可避免地遭受了域差异并阻碍了现实世界应用程序的性能。为了解决这些问题，我们提出了RealFlow，这是一个基于期望最大化的框架，可以直接从任何未标记的现实视频中创建大规模的光流数据集。具体而言，我们首先估计一对视频帧之间的光流，然后根据预测流从该对中合成新图像。因此，新图像对及其相应的流可以被视为新的训练集。此外，我们设计了一种逼真的图像对渲染（RIPR）模块，该模块采用软磁性裂口和双向孔填充技术来减轻图像合成的伪像。在E-Step中，RIPR呈现新图像以创建大量培训数据。在M-Step中，我们利用生成的训练数据来训练光流网络，该数据可用于估计下一个E步骤中的光流。在迭代学习步骤中，流网络的能力逐渐提高，流量的准确性以及合成数据集的质量也是如此。实验结果表明，REALFLOW的表现优于先前的数据集生成方法。此外，基于生成的数据集，我们的方法与受监督和无监督的光流方法相比，在两个标准基准测试方面达到了最先进的性能。我们的代码和数据集可从https://github.com/megvii-research/realflow获得