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Currently, the main application of commercially available three-dimensional forward looking sonar (3D FLS) technology is for real-time vessel navigation. Using 3D FLS technology, the vessel operator can detect not only the range and bearing to a navigational hazard, but also the depth of the hazard in the water column. However, 3D FLS is itself a nascent technology for which many exciting applications...
Pairwise surface rigid registration aims to find the rigid transformation that best register two surfaces represented by point clouds. This work presents a comparison between seven algorithms, with different strategies to tackle rigid registration tasks. We focus on the frame-to-frame problem by using both point clouds and a RGB-D video stream in the experimental results. The former, is considered...
This paper describes the implementation of a 3D handheld scanning approach based on Kinect. User may get the 3D scans at a very fast rate using real time scanning devices like Kinect. These devices have been utilized in several applications, but the scanning lacks in the accuracy and reliability of the 3D data, which makes their employment a difficult task. This research proposed the 3D handheld scanning...
This paper presents a fusion of monocular camera-based metric localization, IMU and odometry in dynamic environments of public roads. We build multiple vision-based maps and use them at the same time in localization phase. For the mapping phase, visual maps are built by employing ORB-SLAM and accurate metric positioning from LiDAR-based NDT scan matching. This external positioning is utilized to correct...
Estimating a depth map from multiple views of a scene is a fundamental task in computer vision. As soon as more than two viewpoints are available, one faces the very basic question how to measure similarity across >2 image patches. Surprisingly, no direct solution exists, instead it is common to fall back to more or less robust averaging of two-view similarities. Encouraged by the success of machine...
We study the problem of single-image depth estimation for images in the wild. We collect human annotated surface normals and use them to help train a neural network that directly predicts pixel-wise depth. We propose two novel loss functions for training with surface normal annotations. Experiments on NYU Depth, KITTI, and our own dataset demonstrate that our approach can significantly improve the...
This paper proposes a new 3D video quality assessment based on 3D visual perception for texture and depth image for measuring the quality of stereoscopic 3D videos by detecting 3D distortions. The effectiveness of the proposed metrics is verified by conducting subjective evaluations on publicly available stereoscopic image databases. Experimental results show that significant consistency can be reached...
Direct method for visual odometry has gained popularity, it needs not to compute feature descriptor and uses the actual values of camera sensors directly. Hence, it is very fast. However, its accuracy and consistency are not satisfactory. Based on these considerations, we propose a tightly-coupled, optimization-based method to fuse inertial measurement unit (IMU) and visual measurement, in which uses...
This paper explores freehand physical interaction in egocentric Mixed Reality by performing a usability study on the use of hand posture estimation sensors. We report on precision, interactivity and usability metrics in a task-based user study, exploring the importance of additional visual cues when interacting. A total of 750 interactions were recorded from 30 participants performing 5 different...
Face verification approaches aim at determining whether two given faces are from the same person. This scenario has several applications, such as information security, forensics, surveillance and smart cards. Several works extract features independently from each face image, i.e., any sort of relation between the two faces is not modeled a priori to either training or classification stages. In this...
Recently, there has been an increased interest in capture, processing and rendering of visual content in form of point clouds. Among other challenges, subjective and objective quality assessments of point clouds are still open problems. Most proposed subjective quality evaluation methodologies are variants or extensions of counter parts from conventional approaches such as those proposed in various...
The increasing availability of point cloud data in recent years is demanding high performance compression solutions. Naturally, methods to perform objective quality assessment of compressed point clouds are also very much needed, namely metrics to measure the geometry distortion of point clouds when positioning errors are present. This is a rather challenging problem since this 3D representation format...
The problem of coverage in three-dimensional (3D) wireless sensor networks is challenging and hard. In this paper, we focus on the problem of k-coverage of a 3D field of interest (FoI), where every point is covered by at least k sensors. First, we propose three sensor placement strategies to guarantee k-coverage of a 3D FoI. Second, we compute the corresponding sensor density. Third, we investigate...
Registration of 3D point set is a very important problem in computer vision. As a widely used algorithm in 3D point set registration, the ICP algorithm has got much attention of researchers. This paper presents a comprehensive survey of the modified ICP algorithms in recent decade by five stages: selection of registration elements, feature metrics, search strategy, Weight of the Point Pair and the...
In this paper we examine the effects of using object poses as guidance to learning robust features for 3D object pose estimation. Previous works have focused on learning feature embeddings based on metric learning with triplet comparisons and rely only on the qualitative distinction of similar and dissimilar pose labels. In contrast, we consider the exact pose differences between the training samples,...
3D dynamic surface tracking is an important research problem and plays a vital role in many computer vision and medical imaging applications. However, it is still challenging to efficiently register surface sequences which has large deformations and strong noise. In this paper, we propose a novel automatic method for non-rigid 3D dynamic surface tracking with surface Ricci flow and Teichmiiller map...
A comprehensive energy balancing concept for the Modular Multilevel Converter (MMC) under unbalanced grid conditions was proposed. Grid supporting converters need to be able to fed unbalanced grid currents; grid failures lead to unbalanced grid voltages. Both unbalanced grid conditions generate energy unbalance inside the MMC. In order to handle these critical operating points, an analytical description...
The problem of measuring the contrast of image elements (objects and background) for complex monochrome images is considered in this paper. A new method for measuring the contrast of image elements is proposed on the basis of analytical assessments of the contrast of the corresponding elements of the initial and inverted images. The new definitions for weighted and relative contrast of image elements...
The human brain consists of two hemispheres, right and left. These two hemispheres are almost symmetrical, not perfectly. However, in neurological diseases, the volumetric losses in the brain begin to deteriorate asymmetrically between the two hemispheres. This deterioration can be local or global in the brain. Symmetry deterioration can be a biomarker in the early stage diagnosis and the following...
Research on the mesh simplification algorithm has been very active in the past years. The color features are very important and can be perceived by human observers. Nevertheless, these features are ignored by most simplification methods. For this reason, this paper presents the salient color features preserving mesh simplification method. First, the multiscale method for the estimation of the color...
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