OpenRaiser/Intern-Atlas huggingface dataset:
Ray Markov Random Fields for image-based 3D modeling: Model and efficient inference
Authors: Shubao Liu, David B. Cooper
Venue: CVPR
Year: 2010

In this paper, we present an approach to multi-view image-based 3D reconstruction by statistically inversing the ray-tracing based image generation process. The proposed algorithm is fast, accurate and does not need any initialization. The geometric representation is a discrete volume divided into voxels, with each voxel associated with two properties: opacity (shape) and color (appearance). The problem is then formulated as inferring each voxel's most probable opacity and color through MAP estimation of the developed Ray Markov Random Fields (RayMRF). RayMRF is constructed with three kinds of cliques: the usual unary and pairwise cliques favoring connected voxel regions, and most importantly ray-cliques modelling the ray-tracing based image generation process. Each ray-clique connects the voxels that the viewing ray passes through. It provides a principled way of modeling the occlusion without approximation. The inference problem involved in the MAP estimation is handled by an optimized belief propagation algorithm. One unusual structure of the proposed MRF is that each ray-clique usually involves hundreds/thousands of random variables, which seems to make the inference computationally formidable. Thanks to the special property of the ray-clique functional form, we investigate the deep factorization property of ray-clique energy and get a highly efficient algorithm based on the general loopy belief propagation, which has reduced the computational complexity from exponential to linear. Both of the efficient inference algorithm and the overall system concept are new. Combining these results in an algorithm that can reverse the image generation process very fast. 3D surface reconstruction in a 100×100×100, i.e., 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> voxel space with 10 images requires roughly 3 minutes on a 3.0 GHz single-core CPU. The running time grows linearly with respect to the number of voxels and the number of images. And the speed could be further improved with a hierarchical sparse representation of the volume, like octree. Experiments on several standard datasets show the quality and speed of the proposed models and algorithms.
Multilinear feature extraction and classification of multi-focal images, with applications in nematode taxonomy
Authors: Min Liu 0008, Amit K. Roy-Chowdhury
Venue: CVPR
Year: 2010

In this paper, we present a 3D X-Ray Transform based multilinear feature extraction and classification method for Digital Multi-focal Images (DMI). In such images, morphological information for a transparent specimen can be captured in the form of a stack of high-quality images, representing individual focal planes through the specimen's body. We present a method that can effectively exploit the entire information in the stack using the 3D X-Ray projections at different viewing angles. These DMI stacks represent the effect of different factors - shape, texture, viewpoint, different instances within the same class and different classes of specimens. For this purpose, we embed the 3D X-Ray Transform within a multilinear framework and propose a Multilinear X-Ray Transform (MXRT) feature representation. By combining the tensor texture and shape information we can get better recognition rates than just relying on the original or key frames of DMI stacks. The experimental results on the nematode DMI data show that the 3D X-Ray Transform based multilinear analysis method can effectively give 100% recognition rate on a real-life database.
Single image depth estimation from predicted semantic labels
Authors: Beyang Liu, Stephen Gould, Daphne Koller
Venue: CVPR
Year: 2010

We consider the problem of estimating the depth of each pixel in a scene from a single monocular image. Unlike traditional approaches, which attempt to map from appearance features to depth directly, we first perform a semantic segmentation of the scene and use the semantic labels to guide the 3D reconstruction. This approach provides several advantages: By knowing the semantic class of a pixel or region, depth and geometry constraints can be easily enforced (e.g., “sky” is far away and “ground” is horizontal). In addition, depth can be more readily predicted by measuring the difference in appearance with respect to a given semantic class. For example, a tree will have more uniform appearance in the distance than it does close up. Finally, the incorporation of semantic features allows us to achieve state-of-the-art results with a significantly simpler model than previous works.
Sparse representation using nonnegative curds and whey
Authors: Yanan Liu, Fei Wu 0001, Zhihua Zhang, Yueting Zhuang, Shuicheng Yan
Venue: CVPR
Year: 2010

It has been of great interest to find sparse and/or nonnegative representations in computer vision literature. In this paper we propose a novel method to such a purpose and refer to it as nonnegative curds and whey (NNCW). The NNCW procedure consists of two stages. In the first stage we consider a set of sparse and nonnegative representations of a test image, each of which is a linear combination of the images within a certain class, by solving a set of regression-type nonnegative matrix factorization problems. In the second stage we incorporate these representations into a new sparse and nonnegative representation by using the group nonnegative garrote. This procedure is particularly appropriate for discriminant analysis owing to its supervised and nonnegativity nature in sparsity pursuing. Experiments on several benchmark face databases and Caltech 101 image dataset demonstrate the efficiency and effectiveness of our nonnegative curds and whey method.
Nonparametric Label-to-Region by search
Authors: Xiaobai Liu, Shuicheng Yan, Jiebo Luo 0001, Jinhui Tang 0001, ZhongYang Huang, Hai Jin 0001
Venue: CVPR
Year: 2010

In this work, we investigate how to propagate annotated labels for a given single image from the image-level to their corresponding semantic regions, namely Label-to-Region (L2R), by utilizing the auxiliary knowledge from Internet image search with the annotated image labels as queries. A nonparametric solution is proposed to perform L2R for single image with complete labels. First, each label of the image is used as query for online image search engines to obtain a set of semantically related and visually similar images, which along with the input image are encoded as Bags-of-Hierarchical-Patches. Then, an efficient two-stage feature mining procedure is presented to discover those input-image specific, salient and descriptive features for each label from the proposed Interpolation SIFT (iSIFT) feature pool. These features consequently constitute a patch-level representation, and the continuity-biased sparse coding is proposed to select few patches from the online images with preference to larger patches to reconstruct a candidate region, which randomly merges the spatially connected patches of the input image. Such candidate regions are further ranked according to the reconstruction errors, and the top regions are used to derive the label confidence vector for each patch of the input image. Finally, a patch clustering procedure is performed as postprocessing to finalize L2R for the input image. Extensive experiments on three public databases demonstrate the encouraging performance of the proposed nonparametric L2R solution.
Search strategies for multiple landmark detection by submodular maximization
Authors: David Liu 0001, Shaohua Kevin Zhou, Dominik Bernhardt, Dorin Comaniciu
Venue: CVPR
Year: 2010

A fundamental issue in multiple landmark detection is the reduction of computational cost. This problem has previously been addressed mainly by reducing the complexity of each individual landmark detector. We address the problem by optimizing the search strategy of multiple landmarks. When the relative positions of landmarks are constrained, the search space can be reduced, thereby reducing the computation. The proposed method leverages the theory of submodular functions to provide a constant factor approximation guarantee of the optimal speed. Although the theory of submodular functions is well known, to the best of our knowledge, this is the first time it is applied to the landmark detection problem. We demonstrate our method by fast and accurate detection of human body landmarks including bones, organs, and vessels in 3D CT images from a diverse dataset of around 2000 volumes with pathological patients. We further provide different search space criteria and variations.
An automatic unsupervised classification of MR images in Alzheimer's disease
Authors: Xiaojing Long, Chris Wyatt 0001
Venue: CVPR
Year: 2010

Image-analysis methods play an important role in helping detect brain changes in and diagnosis of Alzheimer's Disease (AD). In this paper, we propose an automatic unsupervised classification approach to distinguish brain magnetic resonance (MR) images of AD patients from those of elderly normal controls. The symmetric log-domain diffeomorphic demons algorithm, with the properties of symmetry and invertibility, is used to compute the pair-wise registration, whose deformation field is then used to calculate the Riemannian distance between them. The spectral embedding algorithm is performed based on the Riemannian distance matrix to project images onto a low-dimensional space where each image is represented as a point and its neighboring points correspond to images of high anatomical similarity. Finally, the quick shift clustering method is employed in the embedded space to partition the dataset into subgroups. The experiments using the proposed method show very good performance for clustering images into AD and normal aging, using the Clinical Dementia Rating (CDR) scale as a comparison.
Cost-sensitive subspace learning for face recognition
Authors: Jiwen Lu, Yap-Peng Tan
Venue: CVPR
Year: 2010

Conventional subspace learning-based face recognition aims to attain low recognition errors and assumes same loss from all misclassifications. In many real-world face recognition applications, however, this assumption may not hold as different misclassifications could lead to different losses. For example, it may cause inconvenience to a gallery person who is mis-recognized as an impostor and not allowed to enter the room by a face recognition-based door-locker, but it could result in a serious loss or damage if an impostor is mis-recognized as a gallery person and allowed to enter the room. Motivated by this concern, we propose in this paper a cost-sensitive subspace learning approach for face recognition. Our approach incorporates a cost matrix, which specifies the different costs associated with misclassifications of subjects, into three popular subspace learning algorithms and devise the corresponding cost-sensitive methods, namely, cost-sensitive principal component analysis (CSPCA), cost-sensitive linear discriminant analysis (CSLDA), and cost-sensitive locality preserving projections (CSLPP), to achieve a minimum overall recognition loss by performing recognition in the low-dimensional subspaces derived. Experimental results are presented to demonstrate the efficacy of the proposed approach.
A framework for ultra high resolution 3D imaging
Authors: Zheng Lu 0002, Yu-Wing Tai, Moshe Ben-Ezra, Michael S. Brown
Venue: CVPR
Year: 2010

We present an imaging framework to acquire 3D surface scans at ultra high-resolutions (exceeding 600 samples per mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ). Our approach couples a standard structured-light setup and photometric stereo using a large-format ultra-high-resolution camera. While previous approaches have employed similar hybrid imaging systems to fuse positional data with surface normals, what is unique to our approach is the significant asymmetry in the resolution between the low-resolution geometry and the ultra-high-resolution surface normals. To deal with these resolution differences, we propose a multi-resolution surface reconstruction scheme that propagates the low-resolution geometric constraints through the different frequency bands while gradually fusing in the high-resolution photometric stereo data. In addition, to deal with the ultra-high-resolution images, our surface reconstruction is performed in a patch-wise fashion and additional boundary constraints are used to ensure patch coherence. Based on this multi-resolution reconstruction scheme, our imaging framework can produce 3D scans that show exceptionally detailed 3D surfaces far exceeding existing technologies.
Compression of surface registrations using Beltrami coefficients
Authors: Lok Ming Lui, Tsz Wai Wong, Paul M. Thompson, Tony F. Chan, Xianfeng Gu, Shing-Tung Yau
Venue: CVPR
Year: 2010

Surface registration is widely used in machine vision and medical imaging, where 1-1 correspondences between surfaces are computed to study their variations. Surface maps are usually stored as the 3D coordinates each vertex is mapped to, which often requires lots of storage memory. This causes inconvenience in data transmission and data storage, especially when a large set of surfaces are analyzed. To tackle this problem, we propose a novel representation of surface diffeomorphisms using Beltrami coefficients, which are complex-valued functions defined on surfaces with supreme norm less than 1. Fixing any 3 points on a pair of surfaces, there is a 1-1 correspondence between the set of surface diffeomorphisms between them and the set of Beltrami coefficients on the source domain. Hence, every bijective surface map can be represented by a unique Bel-trami coefficient. Conversely, given a Beltrami coefficient, we can reconstruct the unique surface map associated to it using the Beltrami Holomorphic flow (BHF) method introduced in this paper. Using this representation, 1/3 of the storage space is saved. We can further reduce the storage requirement by 90% by compressing the Beltrami coefficients using Fourier approximations. We test our algorithm on synthetic data, real human brain and hippocampal surfaces. Our results show high accuracy in the reconstructed data, while the amount of storage is greatly reduced. Our approach is compared with the Fourier compression of the coordinate functions using the same amount of data. The latter approach often shows jaggy results and cannot guarantee to preserve diffeomorphisms.
Anomaly detection in crowded scenes
Authors: Vijay Mahadevan, Weixin Li 0002, Viral Bhalodia, Nuno Vasconcelos
Venue: CVPR
Year: 2010

A novel framework for anomaly detection in crowded scenes is presented. Three properties are identified as important for the design of a localized video representation suitable for anomaly detection in such scenes: (1) joint modeling of appearance and dynamics of the scene, and the abilities to detect (2) temporal, and (3) spatial abnormalities. The model for normal crowd behavior is based on mixtures of dynamic textures and outliers under this model are labeled as anomalies. Temporal anomalies are equated to events of low-probability, while spatial anomalies are handled using discriminant saliency. An experimental evaluation is conducted with a new dataset of crowded scenes, composed of 100 video sequences and five well defined abnormality categories. The proposed representation is shown to outperform various state of the art anomaly detection techniques.
DARTs: Efficient scale-space extraction of DAISY keypoints
Authors: David Marimon, Arturo Bonnin, Tomasz Adamek, Roger Gimeno
Venue: CVPR
Year: 2010

Winder et al. have recently shown the superiority of the DAISY descriptor in comparison to other widely extended descriptors such as SIFT and SURF. Motivated by those results, we present a novel algorithm that extracts viewpoint and illumination invariant keypoints and describes them with a particular implementation of a DAISY-like layout. We demonstrate how to efficiently compute the scale-space and re-use this information for the descriptor. Comparison to similar approaches such as SIFT and SURF show higher precision vs recall performance of the proposed method. Moreover, we dramatically reduce the computational cost by a factor of 6x and 3x, respectively. We also prove the use of the proposed method for computer vision applications.
Multiview constraints in frequency space and camera calibration from unsynchronized images
Authors: Hiroki Matsumoto, Jun Sato, Fumihiko Sakaue
Venue: CVPR
Year: 2010

In this paper, we propose a method for calibrating relative position and orientation of multiple unsynchronized cameras from general moving points. If the sampling times of multiple cameras are different from each other, there is no corresponding point in the images of moving points and we cannot calibrate these cameras. In this paper we analyze geometric relationships of multiple cameras in the frequency space, and show that they enable us to calibrate multiple unsynchronized cameras accurately even if exact corresponding points do not exist in images. The proposed method does not require any interpolation of moving points in images.
Unified graph matching in Euclidean spaces
Authors: Julian J. McAuley, Teofilo de Campos, Tibério S. Caetano
Venue: CVPR
Year: 2010

Graph matching is a classical problem in pattern recognition with many applications, particularly when the graphs are embedded in Euclidean spaces, as is often the case for computer vision. There are several variants of the matching problem, concerned with isometries, isomorphisms, homeomorphisms, and node attributes; different approaches exist for each variant. We show how structured estimation methods from machine learning can be used to combine such variants into a single version of graph matching. In this paradigm, the extent to which our datasets reveal isometries, isomorphisms, homeomorphisms, and other properties is automatically accounted for in the learning process so that any such specific qualification of graph matching loses meaning. We present experiments with real computer vision data showing the leverage of this unified formulation.
Simultaneous surveillance camera calibration and foot-head homology estimation from human detections
Authors: Branislav Micusík, Tomás Pajdla
Venue: CVPR
Year: 2010

We propose a novel method for automatic camera calibration and foot-head homology estimation by observing persons standing at several positions in the camera field of view. We demonstrate that human body can be considered as a calibration target thus avoiding special calibration objects or manually established fiducial points. First, by assuming roughly parallel human poses we derive a new constraint which allows to formulate the calibration of internal and external camera parameters as a Quadratic Eigenvalue Problem. Secondly, we couple the calibration with an improved effective integral contour based human detector and use 3D projected models to capture a large variety of person and camera mutual positions. The resulting camera auto-calibration method is very robust and efficient, and thus well suited for surveillance applications where the camera calibration process cannot use special calibration targets and must be simple.
Localizing non-overlapping surveillance cameras under the L-Infinity norm
Authors: Branislav Micusík, Roman P. Pflugfelder
Venue: CVPR
Year: 2010

This paper presents a new approach to the problem of camera localization with non-overlapping camera views, particularly relevant for video surveillance systems. We show how to recast localization as quasi-convex optimization under the L-Infinity norm. Thereby we add the problem of reconstructing camera centers and 3D points for non-overlapping cameras with known internal parameters and known rotations to the class of known geometric problems solvable with Second Order Cone Programming. The 3D points are never seen by more than one camera, which makes the localization problem ill-posed. Therefore, the proposed approach employs temporal consistency of the 3D points to supply the missing constraints. Our formulation allows a global optimal solution to be found with a clear physical meaning of the cost function being minimized.
Compact projection: Simple and efficient near neighbor search with practical memory requirements
Authors: Kerui Min, Linjun Yang, John Wright 0001, Lei Wu, Xian-Sheng Hua 0001, Yi Ma 0001
Venue: CVPR
Year: 2010

Image similarity search is a fundamental problem in computer vision. Efficient similarity search across large image databases depends critically on the availability of compact image representations and good data structures for indexing them. Numerous approaches to the problem of generating and indexing image codes have been presented in the literature, but existing schemes generally lack explicit estimates of the number of bits needed to effectively index a given large image database. We present a very simple algorithm for generating compact binary representations of imagery data, based on random projections. Our analysis gives the first explicit bound on the number of bits needed to effectively solve the indexing problem. When applied to real image search tasks, these theoretical improvements translate into practical performance gains: experimental results show that the new method, while using significantly less memory, is several times faster than existing alternatives.
Robust RVM regression using sparse outlier model
Authors: Kaushik Mitra, Ashok Veeraraghavan, Rama Chellappa
Venue: CVPR
Year: 2010

Kernel regression techniques such as Relevance Vector Machine (RVM) regression, Support Vector Regression and Gaussian processes are widely used for solving many computer vision problems such as age, head pose, 3D human pose and lighting estimation. However, the presence of outliers in the training dataset makes the estimates from these regression techniques unreliable. In this paper, we propose robust versions of the RVM regression that can handle outliers in the training dataset. We decompose the noise term in the RVM formulation into a (sparse) outlier noise term and a Gaussian noise term. We then estimate the outlier noise along with the model parameters. We present two approaches for solving this estimation problem: (1) a Bayesian approach, which essentially follows the RVM framework and (2) an optimization approach based on Basis Pursuit Denoising. In the Bayesian approach, the robust RVM problem essentially becomes a bigger RVM problem with the advantage that it can be solved efficiently by a fast algorithm. Empirical evaluations, and real experiments on image de-noising and age estimation demonstrate the better performance of the robust RVM algorithms over that of the RVM reg ression.
"Lattice Cut" - Constructing superpixels using layer constraints
Authors: Alastair Philip Moore, Simon J. D. Prince, Jonathan Warrell
Venue: CVPR
Year: 2010

Unsupervised over-segmentation of an image into super-pixels is a common preprocessing step for image parsing algorithms. Superpixels are used as both regions of support for feature vectors and as a starting point for the final segmentation. Recent algorithms that construct superpixels that conform to a regular grid (or superpixel lattice) have used greedy solutions. In this paper we show that we can construct a globally optimal solution in either the horizontal or vertical direction using a single graph cut. The solution takes into account both edges in the image, and the coherence of the resulting superpixel regions. We show that our method outperforms existing algorithms for computing superpixel lattices. Additionally, we show that performance can be comparable or better than other contemporary segmentation algorithms which are not constrained to produce a lattice.