nils-herrmann/clean_scirepeval huggingface dataset:
Dense matching of multiple wide-baseline views

This paper describes a PDE-based method for dense depth extraction from multiple wide-baseline images. Emphasis lies on the usage of only a small amount of images. The integration of these multiple wide-baseline views is guided by the relative confidence that the system has in the matching to different views. This weighting is fine-grained in that it is determined for every pixel at every iteration. Reliable information spreads fast at the expense of less reliable data, both in terms of spatial communications within a view and in terms of information exchange between the views. Changes in intensity between images can be handled in a similar fine grained fashion.
Modeling scenes with local descriptors and latent aspects

We present a new approach to model visual scenes in image collections, based on local invariant features and probabilistic latent space models. Our formulation provides answers to three open questions:(l) whether the invariant local features are suitable for scene (rather than object) classification; (2) whether unsupennsed latent space models can be used for feature extraction in the classification task; and (3) whether the latent space formulation can discover visual co-occurrence patterns, motivating novel approaches for image organization and segmentation. Using a 9500-image dataset, our approach is validated on each of these issues. First, we show with extensive experiments on binary and multi-class scene classification tasks, that a bag-of-visterm representation, derived from local invariant descriptors, consistently outperforms state-of-the-art approaches. Second, we show that probabilistic latent semantic analysis (PLSA) generates a compact scene representation, discriminative for accurate classification, and significantly more robust when less training data are available. Third, we have exploited the ability of PLSA to automatically extract visually meaningful aspects, to propose new algorithms for aspect-based image ranking and context-sensitive image segmentation.
Synchronizing video sequences

We present a novel method for automatically synchronizing two video sequences of the same event. Unlike previously proposed methods, we do not put any restrictive constraints on the scene nor on the camera motions: our method can deal with independently moving cameras, wide baseline conditions, and general 3D scenes. It starts from five point correspondences throughout the video sequences, that are provided using wide baseline matching and tracking techniques. It is efficient, in that it can be implemented in a non-combinatorial way. The feasibility of the method is demonstrated by preliminary experimental results.
Pedestrian Detection at Warp Speed: Exceeding 500 Detections per Second

Object detection, and in particular pedestrian detection, is a challenging task, due to the wide variety of appearances. The application domain is extremely broad, ranging from e.g. surveillance to automotive safety systems. Many practical applications however often rely on stringent real-time processing speeds combined with high accuracy needs. These demands are contradictory, and usually a compromise needs to be made. In this paper we present a pedestrian detection framework which is extremely fast (500 detections per second) while still maintaining excellent accuracy results. We achieve these results by combining our fast pedestrian detection algorithm (implemented as a hybrid CPU and GPU combination) with the exploitation of scene constraints (using a warping window approach and temporal information), which yields state-of-the-art detection accuracy. We present profound evaluation results of our algorithm concerning both speed and accuracy on the challenging Caltech dataset. Furthermore we present evaluation results on a very specific application showing the full potential of this warping window approach: detection of pedestrians in a truck's blind spot zone.
A Thousand Words in a Scene

This paper presents a novel approach for visual scene modeling and classification, investigating the combined use of text modeling methods and local invariant features. Our work attempts to elucidate (1) whether a textlike bag-of-visterms (BOV) representation (histogram of quantized local visual features) is suitable for scene (rather than object) classification, (2) whether some analogies between discrete scene representations and text documents exist, and 3) whether unsupervised, latent space models can be used both as feature extractors for the classification task and to discover patterns of visual co-occurrence. Using several data sets, we validate our approach, presenting and discussing experiments on each of these issues. We first show, with extensive experiments on binary and multiclass scene classification tasks using a 9,500-image data set, that the BOV representation consistently outperforms classical scene classification approaches. In other data sets, we show that our approach competes with or outperforms other recent more complex methods. We also show that probabilistic latent semantic analysis (PLSA) generates a compact scene representation, is discriminative for accurate classification, and is more robust than the BOV representation when less labeled training data is available. Finally, through aspect-based image ranking experiments, we show the ability of PLSA to automatically extract visually meaningful scene patterns, making such representation useful for browsing image collections.
Continuous Pose Estimation with a Spatial Ensemble of Fisher Regressors

In this paper, we treat the problem of continuous pose estimation for object categories as a regression problem on the basis of only 2D training information. While regression is a natural framework for continuous problems, regression methods so far achieved inferior results with respect to 3D-based and 2D-based classification-and-refinement approaches. This may be attributed to their weakness to high intra-class variability as well as to noisy matching procedures and lack of geometrical constraints. We propose to apply regression to Fisher-encoded vectors computed from large cells by learning an array of Fisher regressors. Fisher encoding makes our algorithm flexible to variations in class appearance, while the array structure permits to indirectly introduce spatial context information in the approach. We formulate our problem as a MAP inference problem, where the likelihood function is composed of a generative term based on the prediction error generated by the ensemble of Fisher regressors as well as a discriminative term based on SVM classifiers. We test our algorithm on three publicly available datasets that envisage several difficulties, such as high intra-class variability, truncations, occlusions, and motion blur, obtaining state-of-the-art results.
Learning to Rank Based on Subsequences

We present a supervised learning to rank algorithm that effectively orders images by exploiting the structure in image sequences. Most often in the supervised learning to rank literature, ranking is approached either by analysing pairs of images or by optimizing a list-wise surrogate loss function on full sequences. In this work we propose MidRank, which learns from moderately sized sub-sequences instead. These sub-sequences contain useful structural ranking information that leads to better learnability during training and better generalization during testing. By exploiting sub-sequences, the proposed MidRank improves ranking accuracy considerably on an extensive array of image ranking applications and datasets.
Exploring Scale-Induced Feature Hierarchies in Natural Images

Recently there has been considerable interest in topic models based on the bag-of-features representation of images. The strong independence assumption inherent in the bag-of-features representation is not realistic however: patches often overlap and share underlying image structures. Moreover, important information with respect to relative scales of the features is completely ignored, for the sake of scale invariance. Considering both spatial and scale-based constraints one can derive spatially constrained natural feature hierarchies within images. We explore the use of topic models that build such spatially constrained scale-induced hierarchies of the features in an unsupervised fashion. Our model uses standard topic models as a starting point. We then incorporate information about the hierarchical and spatial relations of the features into the model. We illustrate the hierarchical nature of the resulting models using datasets of natural images, including the MSRC2 dataset as well as a challenging set of images of trees collected from the Internet.
Automatic object recognition as part of an integrated supervisory control system

The paper consists of two main contributions. First, a generic object recognition based on affinely invariant regions is proposed. Next, this algorithm is used in an integrated supervisory control system (ISCS), with special attention to the human machine interaction. Experiments on an industrial robotic system are included, performing simple tasks such as "Go to object O/sub 1/" or "Put object O/sub 2/ on top of object O/sub 3/", where an object is simply modeled by one or more images thereof.
Markerless augmented reality with a real-time affine region tracker

We present a system for planar augmented reality based on a new real-time affine region tracker. Instead of tracking fiducial points, we track planar local image patches, and bring these into complete correspondence, so a virtual texture can directly be added to them. Moreover, the local image patches can be extracted in an invariant way, even without any a priori information from previous frames. Hence, it is possible to use them as natural beacons, that can be used to recognize the scene and to identify the individual patches. This results in a powerful system that can work without artificial markers or fiducial points and with a minimal amount of user interference.
Localization with omnidirectional images using the radial trifocal tensor

In this paper we present a technique to linearly recover 2D structure and motion in man made environments from three uncalibrated omnidirectional views. We use vertical lines from the scene which are projected as radial lines in the images and are automatically matched. The algorithm is based on a 1D radial trifocal tensor which encodes the relations of the three views and the projected lines. We include experiments with real images, which demonstrate the good performance of the method and its application to robotic tasks, such as robot localization based in a database of reference images or to obtain the initial values of robot and landmarks localization in SLAM algorithms
Mining Multiple Queries for Image Retrieval: On-the-Fly Learning of an Object-Specific Mid-level Representation

In this paper we present a new method for object retrieval starting from multiple query images. The use of multiple queries allows for a more expressive formulation of the query object including, e.g., different viewpoints and/or viewing conditions. This, in turn, leads to more diverse and more accurate retrieval results. When no query images are available to the user, they can easily be retrieved from the internet using a standard image search engine. In particular, we propose a new method based on pattern mining. Using the minimal description length principle, we derive the most suitable set of patterns to describe the query object, with patterns corresponding to local feature configurations. This results in a powerful object-specific mid-level image representation. The archive can then be searched efficiently for similar images based on this representation, using a combination of two inverted file systems. Since the patterns already encode local spatial information, good results on several standard image retrieval datasets are obtained even without costly re-ranking based on geometric verification.
An Analysis of Human-Centered Geolocation

Online social networks contain a constantly increasing amount of images - most of them focusing on people. Due to cultural and climate factors, fashion trends and physical appearance of individuals differ from city to city. In this paper we investigate to what extent such cues can be exploited in order to infer the geographic location, i.e. the city, where a picture was taken. We conduct a user study, as well as an evaluation of automatic methods based on convolutional neural networks. Experiments on the Fashion 144k and a Pinterest-based dataset show that the automatic methods succeed at this task to a reasonable extent. As a matter of fact, our empirical results suggest that automatic methods can surpass human performance by a large margin. Further inspection of the trained models shows that human-centered characteristics, like clothing style, physical features, and accessories, are informative for the task at hand. Moreover, it reveals that also contextual features, e.g. wall type, natural environment, etc., are taken into account by the automatic methods.
DeepProposal: Hunting Objects by Cascading Deep Convolutional Layers

In this paper we evaluate the quality of the activation layers of a convolutional neural network (CNN) for the generation of object proposals. We generate hypotheses in a sliding-window fashion over different activation layers and show that the final convolutional layers can find the object of interest with high recall but poor localization due to the coarseness of the feature maps. Instead, the first layers of the network can better localize the object of interest but with a reduced recall. Based on this observation we design a method for proposing object locations that is based on CNN features and that combines the best of both worlds. We build an inverse cascade that, going from the final to the initial convolutional layers of the CNN, selects the most promising object locations and refines their boxes in a coarse-to-fine manner. The method is efficient, because i) it uses the same features extracted for detection, ii) it aggregates features using integral images, and iii) it avoids a dense evaluation of the proposals due to the inverse coarse-to-fine cascade. The method is also accurate, it outperforms most of the previously proposed object proposals approaches and when plugged into a CNN-based detector produces state-of-the-art detection performance.
Expert Gate: Lifelong Learning with a Network of Experts

In this paper we introduce a model of lifelong learning, based on a Network of Experts. New tasks / experts are learned and added to the model sequentially, building on what was learned before. To ensure scalability of this process, data from previous tasks cannot be stored and hence is not available when learning a new task. A critical issue in such context, not addressed in the literature so far, relates to the decision which expert to deploy at test time. We introduce a set of gating autoencoders that learn a representation for the task at hand, and, at test time, automatically forward the test sample to the relevant expert. This also brings memory efficiency as only one expert network has to be loaded into memory at any given time. Further, the autoencoders inherently capture the relatedness of one task to another, based on which the most relevant prior model to be used for training a new expert, with fine-tuning or learning-without-forgetting, can be selected. We evaluate our method on image classification and video prediction problems.
A relational kernel-based approach to scene classification

Real-world scenes involve many objects that interact with each other in complex semantic patterns. For example, a bar scene can be naturally described as having a variable number of chairs of similar size, close to each other and aligned horizontally. This high-level interpretation of a scene relies on semantically meaningful entities and is most generally described using relational representations or (hyper-) graphs. Popular in early work on syntactic and structural pattern recognition, relational representations are rarely used in computer vision due to their pure symbolic nature. Yet, today recent successes in combining them with statistical learning principles motivates us to reinvestigate their use. In this paper we show that relational techniques can also improve scene classification. More specifically, we employ a new relational language for learning with kernels, called kLog. With this language we define higher-order spatial relations among semantic objects. When applied to a particular image, they characterize a particular object arrangement and provide discriminative cues for the scene category. The kernel allows us to tractably learn from such complex features. Thus, our contribution is a principled and interpretable approach to learn from symbolic relations how to classify scenes in a statistical framework. We obtain results comparable to state-of-the-art methods on 15 Scenes and a subset of the MIT indoor dataset.
Modeling Temporal Structure with LSTM for Online Action Detection

Online action detection is a challenging problem: a system needs to decide what action is happening at the current frame, based on previous frames only. Fortunately in real-life, human actions are not independent from one another: there are strong (long-term) dependencies between them. An online action detection method should be able to capture these dependencies, to enable a more accurate early detection. At first sight, an LSTM seems very suitable for this problem. It is able to model both short-term and long-term patterns. It takes its input one frame at the time, updates its internal state and gives as output the current class probabilities. In practice, however, the detection results obtained with LSTMs are still quite low. In this work, we start from the hypothesis that it may be too difficult for an LSTM to learn both the interpretation of the input and the temporal patterns at the same time. We propose a two-stream feedback network, where one stream processes the input and the other models the temporal relations. We show improved detection accuracy on an artificial toy dataset and on the Breakfast Dataset [21] and the TVSeries Dataset [7], reallife datasets with inherent temporal dependencies between the actions.
Darwintrees for Action Recognition

We propose a novel mid-level representation for action/activity recognition on RGB videos. We model the evolution of improved dense trajectory features not only for the entire video sequence, but also on subparts of the video. Subparts are obtained using a spectral divisive clustering that yields an unordered binary tree decomposing the entire cloud of trajectories of a sequence. We then compute video-darwin on video subparts, exploiting more finegrained temporal information and reducing the sensitivity of the standard time varying mean strategy of videodarwin. After decomposition, we model the evolution of features through both frames of subparts and descending/ascending paths in tree branches. We refer to these mid-level representations as node-darwintree and branch-darwintree respectively. For the final classification, we construct a kernel representation for both mid-level and holistic videodarwin representations. Our approach achieves better performance than standard videodarwin and defines the current state-of-the-art on UCF-Sports and Highfive action recognition datasets.
Kernelized Sorting

Object matching is a fundamental operation in data analysis. It typically requires the definition of a similarity measure between the classes of objects to be matched. Instead, we develop an approach which is able to perform matching by requiring a similarity measure only within each of the classes. This is achieved by maximizing the dependency between matched pairs of observations by means of the Hilbert-Schmidt Independence Criterion. This problem can be cast as one of maximizing a quadratic assignment problem with special structure and we present a simple algorithm for finding a locally optimal solution.
The Combinator: Optimal Combination of Multiple Pedestrian Detectors

In recent years, the accuracy of pedestrian detectors significantly improved. Currently, state-of-the-art pedestrian detectors achieve high accuracy results on challenging datasets. As opposed to refining a single detector, in this paper we propose a different approach to further increase the detection accuracy: combining multiple pedestrian detectors. The most straight-forward way to combine pedestrian detectors would be a naive AND or OR combination. Here, we present a novel generic combination framework in which we exploit specific information from each pedestrian detector to determine the optimal combination parameters. Our main motivation for this approach is based on the fact that several pedestrian detection approaches are based on very different techniques (e.g. a different feature pool), and thus an efficient combination should yield higher accuracy results. Indeed, such a combination is far more powerful, and our experiments indicate that specific (that is, cleverly chosen) combinations outperform existing state-of-the-art pedestrian detection results.
Color features for dating historical color images

Estimating the age of historical photographs is a challenging task for human beings. Only recently this task has been addressed in computational image analysis perspective. The characteristics of the device used to acquire each photograph are discriminative features for this task. We aim at extracting such characteristics from a historical color photographs. The acquisition device mainly effects two properties of the colors: the distribution of their derivatives and the angles drawn by three consecutive pixels in the RGB space. We propose two color features that take advantage of these observations. We show that these two color descriptors (namely color derivatives and color angles) attain the state-of-the-art in the context of image dating.
Multi RGB-D camera setup for generating large 3D point clouds

The advent of inexpensive RGB-D cameras brings new opportunities to capture a 3D environment. This paper presents a method to create a modular setup for generating a large 3D point cloud, with attention to the study of interference, the influence of a USB extension cable, and the calibration procedure. The study of interference includes the influence of the distance between the cameras, the orientation of the cameras, and the illumination. Furthermore, this paper proposes a number of evaluation metrics for similar setups.
Towards Multi-View Object Class Detection

We present a novel system for generic object class detection. In contrast to most existing systems which focus on a single viewpoint or aspect, our approach can detect object instances from arbitrary viewpoints. This is achieved by combining the Implicit Shape Model for object class detection proposed by Leibe and Schiele with the multi-view specific object recognition system of Ferrari et al. After learning single-view codebooks, these are interconnected by so-called activation links, obtained through multi-view region tracks across different training views of individual object instances. During recognition, these integrated codebooks work together to determine the location and pose of the object. Experimental results demonstrate the viability of the approach and compare it to a bank of independent single-view detectors
Guiding the Long-Short Term Memory Model for Image Caption Generation

In this work we focus on the problem of image caption generation. We propose an extension of the long short term memory (LSTM) model, which we coin gLSTM for short. In particular, we add semantic information extracted from the image as extra input to each unit of the LSTM block, with the aim of guiding the model towards solutions that are more tightly coupled to the image content. Additionally, we explore different length normalization strategies for beam search to avoid bias towards short sentences. On various benchmark datasets such as Flickr8K, Flickr30K and MS COCO, we obtain results that are on par with or better than the current state-of-the-art.