Block based dense stereo matching using adaptive cost aggregation and limited disparity estimation

This paper presents a new local binocular stereo matching algorithm. A local window with adaptive support weights is used to aggregate matching costs. A more robust matching score is set up combining sum of absolute intensity differences and a gradient based measure. Each pixel has a different disparity search range according to disparity gradient analysis and computational complexity decreases rapidly. Experimental results using the Middlebury stereo test bed demonstrate the validity of our presented approach.

Innovative applications in rapidly evolving domains such as robotic navigation and autonomous (driverless) vehicles rely on binocular computer vision systems that meet stringent response time and accuracy requirements. A key problem in these vision systems is stereo matching, which involves matching pixels from two input images in order to construct the output, a 3D map. Building upon the existing local stereo matching algorithms, this paper proposes a novel stereo matching algorithm that is based on a weighted guided filtering foundation. The proposed algorithm consists of three main steps; each step is designed with the goal of improving accuracy. First, the matching costs are computed using a unique combination of complementary methods (absolute difference, Census, and gradient algorithms) to reduce errors. Second, the costs are aggregated using an adaptive weighted guided image filtering method. Here, the regularization parameters are adjusted adaptively using the Canny method, further reducing errors. Third, a disparity map is generated using the winner-take-all strategy; this map is subsequently refined using a densification method to reduce errors. Our experimental results indicate that the proposed algorithm provides a higher level of accuracy in comparison to a collection of the existing state-of-the-art local algorithms.

With the wide application of artificial intelligence in intelligent driving, visual SLAM technology has become one of the popular research areas. Binocular SLAM, as one of the cheapest cost technologies in SLAM, has become a research hotspot for many scholars. For the problems of high time consumption, poor accuracy and high mis-matching rate of traditional binocular stereo matching algorithm, an adaptive weight cost aggregation D* algorithm based on Dijkstra's idea is proposed. The algorithm improves on the local stereo matching Census algorithm, and fuses the Census algorithm and grayscale histogram in the cost matching stage to make it compatible with computational efficiency and accuracy, which can achieve real-time effect when combined with hardware acceleration. The experimental results show that the improved Census algorithm greatly improves the stereo matching accuracy, and computational efficiency. In comparison with other algorithms on the Middlebury 2.0 testbed, the improved algorithm is found to be 42% more efficient and 1.2% better in terms of mis-matching rate.

In this study, novel techniques are presented addressing the challenges of stereo matching algorithms for surveillance and vehicle control. For this purpose, one of the most efficient local stereo matching techniques, namely permeability filter, is modified in terms of road plane geometry and temporal consistency in order to take the major challenges of such a scenario into account. Relaxing smoothness assumption of the permeability filter along vertical axis enables extraction of road geometry with high accuracy, even for the cases where ground plane does not contain sufficient textural information. On the other hand, temporal smoothness is enforced by transferring reliable depth assignments against illumination changes, reflections and instant occlusions. According to the extensive experiments on a recent challenging stereo video dataset, the proposed modifications provide reliable disparity maps under severe challenges and low texture distribution, improving scene analyses for surveillance related applications. Although improvements are illustrated for a specific local stereo matching algorithm, the presented specifications and modifications can be applied for the other similar stereo algorithms as well.

Human beings process stereoscopic correspondence across multiple purposes like robot navigation, automatic driving, and virtual or augmented reality. However, this bioinspiration is ignored by state-of-the-art dense stereo correspondence matching methods. Cost aggregation is one of the critical steps in the stereo matching method. In this article, we propose an optimized cross-scale cost aggregation scheme with coarse-to-fine strategy for stereo matching. This scheme implements cross-scale cost aggregation with the smoothness constraint on neighborhood cost, which essentially extends the idea of the inter-scale and intra-scale consistency constraints to increase the matching accuracy. The neighborhood costs are not only used in the intra-scale consistency to ensure that the regularized costs vary smoothly in an eight-connected neighbors region but also incorporated with inter-scale consistency to optimize the disparity estimation. Additionally, the improved method introduces an adaptive scheme in each scale with different aggregation methods. Finally, experimental results evaluated both on classic Middlebury and Middlebury 2014 data sets show that the proposed method performs better than the cross-scale cost aggregation. The whole stereo correspondence algorithm achieves competitive performance in terms of both matching accuracy and computational efficiency. An extensive comparison, including the KITTI benchmark, illustrates the better performance of the proposed method also.

Outlier detection and disparity refinement in stereo matching

A hierarchical stereo matching algorithm based on adaptive support region aggregation method

A fast stereo matching algorithm suitable for embedded real-time systems

The production of stereoscopic 3D HD content is considerably increasing and experience in 2-view acquisition is in progress. High quality material to the audience is required but not always ensured, and correction of the stereo views may be required. This is done via disparity-compensated view synthesis. A robust method has been developed dealing with these acquisition problems that introduce discomfort (e.g hyperdivergence and hyperconvergence...) as well as those ones that may disrupt the correction itself (vertical disparity, color difference between views...). The method has three phases: a preprocessing in order to correct the stereo images and estimate features (e.g. disparity range...) over the sequence. The second (main) phase proceeds then to disparity estimation and view synthesis. Dual disparity estimation based on robust block-matching, discontinuity-preserving filtering, consistency and occlusion handling has been developed. Accurate view synthesis is carried out through disparity compensation. Disparity assessment has been introduced in order to detect and quantify errors. A post-processing deals with these errors as a fallback mode. The paper focuses on disparity estimation and view synthesis of HD images. Quality assessment of synthesized views on a large set of HD video data has proved the effectiveness of our method.

Real-time stereo matching with high accuracy is a dynamic research topic; it is attractive in diverse computer vision applications. This paper presents a stereo-matching algorithm that produces high-quality disparity map while maintaining real-time performance. The proposed stereo-matching method is based on three per-pixel difference measurements with adjustment elements. The absolute differences and the gradient matching are combined with a colour-weighted extension of complete rank transform to reduce the effect of radiometric distortion. The disparity calculation is realized using improved dynamic programming that optimizes along and across all scanlines. It solves the inter-scanline inconsistency problem and increases the matching accuracy. The proposed algorithm is implemented on parallel high-performance graphic hardware using the Compute Unified Device Architecture to reach over 240 million disparity evaluations per second. The processing speed of our algorithm reaches 98 frames per second on 240 × 320-pixel images and 32 disparity levels. Our method ranks fourth in terms of accuracy and runtime for quarter-resolution images in the Middlebury stereo benchmark.

Similarity measuring plays as an import role in stereo matching, whether for visual data from standard cameras or for those from novel sensors such as Dynamic Vision Sensors (DVS). Generally speaking, robust feature descriptors contribute to designing a powerful similarity measurement, as demonstrated by classic stereo matching methods. However, the kind and representative ability of feature descriptors for DVS data are so limited that achieving accurate stereo matching on DVS data becomes very challenging. In this paper, a novel feature descriptor is proposed to improve the accuracy for DVS stereo matching. Our feature descriptor can describe the local context or distribution of the DVS data, contributing to constructing an effective similarity measurement for DVS data matching, yielding an accurate stereo matching result. Our method is evaluated by testing our method on groundtruth data and comparing with various standard stereo methods. Experiments demonstrate the efficiency and effectiveness of our method.

This paper proposes a stochastic approach to estimate the occlusion and disparity fields of stereoscopic images. The fields are estimated by the Bayesian maximum a posteriori (MAP) framework and Markov random field (MRF) models. The occlusion field model is based on the stochastic observation that the probability distribution in MAP estimator is relatively unstable and uniform at occluded regions. The occlusion is explicitly modelled as MRF, and is estimated in an energy optimization method called stochastic diffusion. The detected occluded region is compensated for the re-estimated disparity field in the same stochastic diffusion and the dynamic programming approach. Experimental results show good occlusion detection and disparity estimation. These results show the novel stochastic approach is suitable for occlusion detection and disparity estimation.

Stereo matching techniques aim at reconstructing disparity maps from a pair of images. The use of stereo matching techniques in embedded systems is very challenging due to the complexity of the state-of-the-art algorithms. Local stereo matching algorithms are efficiently implemented on GPU and DSP. This paper presents the optimization of the One Dimension Belief Propagation (BP-1D) algorithm. BP-1D is faster than previous algorithms on monocore DSP and its implementation onto multicore DSPs is straightforward. BP-1D implemented on multicore embedded platforms out-performs previous stereo matching implementations reaching real-time performances for resolutions up to 1080p with a 10 Watts power consumption.

Warping-based spectral translation network for unsupervised cross-spectral stereo matching

Adaptive support weight (ASW) strategies in local stereo matching have recently attracted many researchers due to their compelling results. In this paper, we present an evaluation study that focuses on weight computation methods that have been suggested in the most recent literature. We implemented 9 ASW stereo methods and tested them on all (35) ground truth test stereo image pairs of the Middlebury benchmark. Our evaluation considers both the accuracy of the matching process and the computational efficiency of its GPU implementation. According to our results, high-quality matching results at real-time processing speeds can be achieved by using the guided image filter weights.