Reference View Research Articles

Evaluation of available height, location, and patency of the ostium for sinus augmentation from an implant treatment planning perspective.

PurposeThe objective of this study was to evaluate the amount of height available for a maxillary sinus augmentation procedure without blocking the ostium and jeopardizing the drainage of the ostiomeatal complex using cone-beam computed tomography (CBCT) imaging.Materials and MethodsA total of 200 sinonasal complexes comprising 100 dentate and 100 edentulous scans were retrospectively assessed using CBCT. Invivo 5.0, a CBCT reconstruction program, was used for image evaluation. The coronal section demonstrating the ostiomeatal complex was selected as a reference view to perform measurements of the sinus. The measurements were done by 2 evaluators in separate sessions. Comparative analyses of measurements were performed between dentate and edentulous patients and between male and female patients.ResultsThe safe height to which the sinus can be elevated without compromising the integrity of the ostiomeatal complex was calculated for each sinus. In the presence of significant mucosal thickening, the height available for augmentation was calculated by subtracting the height of mucosal thickening from the sinus floor to the location of the ostium. In this study, the available height was approximately 27.05 mm for dentate and 23.40 mm for edentulous patients. The inter-operator reliability was excellent for all the parameters evaluated.ConclusionThis retrospective study with a limited number of patients from a single university-based site shows that CBCT is valuable in evaluating the location and patency of the ostium for planning sinus augmentation procedures for dental implant placement.

Control PID basado en odometría visual monocular a un vehículo de superficie marino

The aim of this work is to study the behavior of a marine vehicle applying vision-based control. We use a DMVO algorithm (Direct Monocular Visual Odometry) that is based at the feature extraction of two image frames taken consecutively at two continuous tame frames in order to estimate a marine vehicle’s position; vehicle’s dynamics are modeled without external perturbations and therefore apply a vision based Proportional Integral Derivative (PID) control for the study of its behavior through simulations using computational tools to simulate a 3D scenario and get the matrix that contains the image from the inertial frame of reference view from the vehicle. First we need a static scenario that contains reference points such that we are able to apply the proposed vision based PID control; the virtual scenario was designed at the MATLAB’s virtual world editor that let us add sensors such as cameras, and set their parameters for make the study and simulations such as path following.

Learning Collision-Free Space Detection From Stereo Images: Homography Matrix Brings Better Data Augmentation

Collision-free space detection is a critical component of autonomous vehicle perception. The state-of-the-art algorithms are typically based on supervised deep learning. Their performance is dependent on the quality and amount of labeled training data. It remains an open challenge to train deep convolutional neural networks (DCNNs) using only a small quantity of training samples. Therefore, in this article, we mainly explore an effective training data augmentation approach that can be employed to improve the overall DCNN performance, when additional images captured from different views are available. Due to the fact that the pixels in collision-free space (generally regarded as a planar surface) between two images, captured from different views, can be associated using a homography matrix, the target image can be transformed into the reference view. This provides a simple but effective way to generate training data from additional multiview images. Extensive experimental results, conducted with six state-of-the-art semantic segmentation DCNNs on three datasets, validate the effectiveness of the proposed method for enhancing collision-free space detection performance. When validated on the KITTI road benchmark, our approach provides the best results, compared with other state-of-the-art stereo vision-based collision-free space detection approaches.

Improving the detection of subscapularis tears using a specific transverse CT arthrography image

BackgroundThe prevalence of subscapularis (SSC) tendon tears is often underestimated. This negatively impacts the shoulder function because the SSC muscle is a powerful internal rotator. The primary aim of this study was to compare a blended clinical and radiological preoperative index of suspicion for SSC tears to the arthroscopic findings. The secondary aim was to compare the surgeon's and radiologist's index of suspicion to determine which is more accurate. HypothesisAnalyzing a transverse image passing under the tip of the coracoid process, in combination with clinical examination, will be the standard for detecting SSC tears. MethodsThis prospective study enrolled 50 consecutive patients who underwent shoulder arthroscopy. Preoperatively, four clinical tests were doneto detect SSC tears: lift-off, internal rotation lag sign, bear-hug, belly-press. A CT arthrography slice passing under the coracoid process tip was analyzed by the surgeon. The surgeon deduced a radiological index of suspicion for SSC tears then a blended clinical and radiological index of suspicion based on the clinical examination. Lastly, the surgeon looked at the radiologist's findings and index of suspicion for a lesion. The three indexes of suspicion were compared with the actual arthroscopy findings. ResultsThe surgeon's blended clinical and radiological index of suspicion was similar to his radiological index. Both of the surgeon's indexes of suspicion were higher than the radiologist's. The prevalence of SSC tears was 58 %. DiscussionWe recommend doing multiple clinical tests as they complement each other in detecting SSC tears, since each one activates a different portion of the muscle. We advise surgeons to supplement their clinical examination by analyzing a specific image of the tendon below the coracoid, as the reference view for the starting point of SSC tears. Level of evidenceIV, prospective diagnostic study on consecutive patients.

Motion Compensated Virtual View Synthesis Using Novel Particle Cell

Due to the wide interest in advanced multimedia experience, free-viewpoint communication is being greatly developed in recent years. In the free-viewpoint communication, viewers can perceive a view from any angle and any position of a scene. Even though the preferred views are not captured, we can generate the views through virtual view synthesis that synthesizes an arbitrary view from captured reference view(s). For daily use, only one or few cameras in baseline distance are given to capture the scene that makes the virtual view synthesis challenging. The task is more difficult when the camera is continuously moving. In this paper, we propose a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">particle cell</i> to model a reference view sequence to a set of moving particles for virtual view synthesis. Using our novel hybrid motion estimation scheme, the projected coordinates of particles in each frame are obtained even they are occluded. The particles are warped to a virtual view and synthesized as a virtual view sequence. Our method is applicable for both dynamic camera setting and static camera setting. The experimental results show our method outperforms the state-of-the-art algorithms in dynamic camera datasets and presents improvement in static camera datasets in general.

WARHOL: Wearable Holographic Object Labeler

MPEG-I, the upcoming standard for immersive video, has steadily explored immersive video technology for free navigation applications, where any virtual viewpoint to the scene is created using Depth Image-Based Rendering (DIBR) from any number of stationary cameras positioned around the scene. This exploration has recently evolved towards a rendering pipeline using camera feeds, as well as a standard file format, containing all information for synthesizing a virtual viewpoint to a scene. We present an acceleration of our Reference View Synthesis software (RVS) that enables the rendering in real-time of novel views in a head mounted display, hence supporting virtual reality (VR) with 6 Degrees of Freedom (6DoF) including motion parallax within a restricted viewing volume. In this paper, we explain its main engineering challenges.

Local Foreground Removal Disocclusion Filling Method for View Synthesis

View synthesis is an effective method to generate the contents of multiple views based on a limited number of reference views, which can be used in 2D to 3D conversion, free viewpoint video and multiview video rendering. Depth-image-based rendering (DIBR) is a practical technique to generate virtual view by using a 2D reference view and its depth image. However, a critical problem in DIBR process is that disocclusions might be produced in the synthesized image because the background occluded by the foreground objects in the reference view may be exposed in the virtual view. In this paper, a local foreground removal method is proposed for disocclusion filling. Morphology-based depth image preprocessing is performed before DIBR, aiming to correct the depth value of the ghosts and remove ghost artifacts. In the synthesized virtual image, pixels on the disocclusion edge are identified and classified. Then they are positioned in the reference image by inverse 3D warping. Local foreground regions that occlude the corresponding background are removed from both the reference image and its depth image based on the disocclusion edge pixels. Removed region is filled with surrounding background contents, and depth information is used in this process to prevent foreground penetration. The predicted background contents are warped to the disocclusion region, thereby achieving the hole filling. Experimental results show that the proposed method performs better than the other methods in disocclusion filling, and improves the subjective and objective quality of the synthesized view. In the evaluation results of PSNR, SSIM, FSIMc and VSI, our method improves by 0.32-2.43dB, 0.0036-0.0155, 0.0041-0.0198 and 0.0012-0.0057 respectively compared with competitive methods.

Rate-Distortion Driven Decomposition of Multiview Imagery to Diffuse and Specular Components

In this work, we propose an overcomplete representation of multiview imagery for the purpose of compression. We present a rate-distortion (R-D) driven approach to decompose multiview datasets into two additive parts which can be interpreted as diffuse and specular content. We choose distinct and different sparsifying transforms for the diffuse and specular components and employ an R-D inspired measure as our optimization cost function to drive the decomposition based solely on compressibility. We first describe a framework which performs data separation in a registered domain to avoid the complexity of warping between views. Then a more comprehensive approach is proposed to separate specular data progressively from coordinates of multiple reference views. Experimental results show a coding gain of up to 0.6 dB for synthetic datasets and up to 0.9 dB for real datasets.

Confidence-Based Large-Scale Dense Multi-View Stereo

Albeit remarkable progress has been made to improve the accuracy and completeness of multi-view stereo (MVS), existing methods still suffer from either sparse reconstructions of low-textured surfaces or heavy computational burden. In this paper, we propose a Confidence-based Large-scale Dense Multi-view Stereo (CLD-MVS) method for high resolution imagery. Firstly, we formulate MVS as a multi-view depth estimation problem, and employ a normal-aware efficient PatchMatch stereo to estimate the initial depth and normal map for each reference view. A self-supervised deep learning method is then developed to predict the spatial confidence for multi-view depth maps, which is combined with cross-view consistency to generate the ground control points. Subsequently, a confidence-driven and boundary-aware interpolation scheme using static and dynamic guidance is adopted to synthesize dense depth and normal maps. Finally, a refinement procedure which leverages synthesized depth and normal as prior is conducted to estimate cross-view consistent surface. Experiments show that the proposed CLD-MVS method achieves high geometric completeness while preserving fine-scale details. In particular, it has ranked No. 1 on the ETH3D high-resolution MVS benchmark in terms of F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> -score.

激光近距探测装置抗云雾干扰研究

Aerosol-interference is a serious interference source for active optical target-detection device (AOTD) when it is used in lower sky or super low sky. When AOTD in a vehicle passes through aerosol, it may be wrong armed, even give out execution signal before right time. In order to increase the ability in aerosol environment, how the AOTD worked and how the aerosol interfered the AOTD were analyzed. It also showed out the techniques of anti-aerosol-interference used in engineering. The general techniques for anti-aerosol-interference were settings of cut-off distance method, weaken methods by optical parts, optical field restraining method, cancellation by symmetric views, setting reference view field, body recognition method, composite with Ka detectors, decreasing the width of transmitted pulse, image recognition method et al. Among these methods, the multimode detection method was a valuable way. Effects of different anti-interference methods were listed, the results shows integrated application of all the methods can increase the ability of AOTD.

A Real-Time Super Multiview Rendering Pipeline for Wide Viewing-Angle and High-Resolution 3D Displays Based on a Hybrid Rendering Technique

Super multiview (SMV) 3D displays with a directional diffuser can provide dense viewpoints, wide viewing angles and high image quality. However, traditional SMV 3D rendering pipelines have many disadvantages, such as high time costs, low image quality, incorrect lighting effects and limited viewing angles. To overcome the abovementioned drawbacks, we propose a new SMV 3D rendering pipeline based on a hybrid rendering technique (HRT) that effectively combines and improves the Turing multiview rendering technique, the multiple view plus depth (MVD) technique and the deferred shading technique, introducing additional normal information, diffuseness information and shininess information into the SMV 3D rendering pipeline. The SMV HRT pipeline can generate SMV 3D images with accurate lighting in real time when the viewpoint number of an SMV 3D display is greater than 50, the viewing angle is greater than 100 degrees, the resolution of a single viewpoint image is more than 512*512 and the resolution of the LCD panel is 7680*4320; in particular, complex scenes can be generated in real time. The proposed HRT pipeline is the only viable real-time rendering pipeline with accurate lighting effects for super multiview 3D displays with wide viewing angle and high resolution that runs on a common PC with standard graphics hardware. An 8k SMV 3D display with an 80° viewing angle and 100 viewpoints is applied to demonstrate the validity of the HRT method in experiments. When the number of reference views is four, the experimental results show that the rendering frame rate is more than 35 fps on average for complex virtual scenes, and the peak signal-to-noise ratio (PSNR) value of the HRT is greater than 36 dB, illustrating its high image quality and accurate lighting. Compared with state-of-the-art MVD methods, HRT processes more lighting information and is more suitable for virtual scene rendering. Therefore, the HRT method has advantages regarding the image quality of the reconstructed 3D image and can easily achieve real-time rendering for SMV 3D displays with wide viewing angles.

Joint Texture/Depth Power Allocation for 3-D Video SoftCast

Recently, a novel uncoded (pseudoanalog) scheme called SoftCast is proposed for wireless video transmission, which eliminates the cliff effect of the state-of-the-art source-channel coding based schemes and achieves linear quality transition within a wide range of channel signal-to-noise ratio. Therefore, SoftCast-like uncoded and hybrid transmission has become an attractive research issue for natural 2-D video. However, very few studies focus on the SoftCast-based wireless transmission of the 3-D video (3DV) currently. One critical issue of 3DV SoftCast is how to allocate the limited power budget of the transmitter to the texture videos and depth maps of the 3DV to achieve the optimal overall quality on the receiver side, including the transmission quality of the reference views and the synthesis quality of the virtual views. This paper attempts to solve the optimal joint power allocation problem in an efficient way. First, we formulate the target problem as a constrained power-distortion optimization (PDO) problem mathematically. Then, each part of the distortion is analyzed and formulated in a closed form. Finally, the PDO problem is mapped to an unconstrained convex optimization problem and solved by the Lagrangian multiplier method. Simulation results demonstrate that the performance of the proposed method is close to that of the full search method, which can provide the best performance theoretically. Nevertheless, the complexity of the proposed method is negligible compared with that of the full search method. In addition, as compared with the fixed ratio (e.g., 1:1) power allocation between texture and depth, the proposed method can achieve a PNSR gain up to 1.8 dB.

Trifocal tensor-based 6-DOF visual servoing

This paper proposes a trifocal tensor-based approach for six-degree-of-freedom visual servoing. The trifocal tensor model among the current, desired, and reference views is constructed to describe the geometric relationship of the system. More precisely, to ensure the computation consistency of trifocal tensor, a virtual reference view is introduced by exploiting the transfer relationships between the initial and desired images. Instead of resorting to explicit estimation of the camera pose, a set of visual features with satisfactory decoupling properties are constructed from the tensor elements. Based on the selected features, a visual controller is developed to regulate the camera to a desired pose, and an adaptive update law is used to compensate for the unknown distance scale factor. Furthermore, the system stability is analyzed via Lyapunov-based techniques, showing that the proposed controller can achieve almost global asymptotic stability. Both simulation and experimental results are provided to demonstrate the effectiveness and robustness of our approach under different conditions and case studies.

Hindbrain morphometry and choroid plexus position in differential diagnosis of posterior fossa cystic malformations.

To assess the differential diagnostic significance of a series of quantitative and qualitative variables of the cerebellar vermis in fetuses with posterior fossa cystic malformation, including Dandy-Walker malformation (DWM), vermian hypoplasia (VH) and Blake's pouch cyst (BPC). This was a retrospective study of confirmed cases of DWM, VH and BPC, diagnosed at the Fetal Medicine and Surgery Unit of the Federico II University between January 2005 and June 2013 or the Fetal Medicine and Surgery Unit of G. Gaslini Hospital between July 2013 and September 2017. All included cases had good-quality three-dimensional (3D) volume datasets of the posterior fossa, acquired by transvaginal ultrasound through the posterior fontanelle. The midsagittal view of the posterior fossa was the reference view for the study. We assessed brainstem-tentorium angle and brainstem-vermis angle (BVA), as well as craniocaudal (CCVD) and anteroposterior (APVD) vermian diameters and vermian area (VA), which were normalized by biparietal diameter (BPD) to take into account gestational age (CCVD/BPD × 100, APVD/BPD × 100 and VA/BPD × 100, respectively). Finally, the position of the fourth ventricular choroid plexus (4VCP) was defined as normal ('up') or abnormal ('down'), relative to the roof/cyst inlet of the fourth ventricle. We analyzed 67 fetuses with posterior fossa malformations (24 cases of DWM, 13 of VH and 30 of BPC). The mean gestational age at diagnosis was 23.6 weeks. Regardless of gestational age, the BVA differed significantly between the three groups, and the VA/BPD was able to differentiate between VH and BPC. In differentiating between VH and BPC, the greatest areas under the receiver-operating characteristics curve were those for VA/BPD ratio. The 4VCP position was down in all cases of DWM and VH, while it was up in all cases of BPC. Our data support the concept that VA/BPD ratio and 4VCP position may be used to differentiate between DWM, VH and BPC in the fetus. In our series, the position of the 4VCP had the highest accuracy, but a larger number of VH cases should be evaluated to confirm that an up position of the 4VCP indicates BPC while a down position indicates DWM or VH. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Evaluation of the efficacy of a self-training programme in focus cardiac ultrasound with simulator

Focus cardiac ultrasound is a great tool for quick evaluation of cardiac function in acute settings with limited time and expertise in echocardiography. Adequate training is essential for physicians willing to use this imaging technique. The goal of this study was to assess the efficacy of a self-training programme using a cardiac ultrasound simulator. Thirty-five trainees in cardiology, emergency medicine or anaesthesiology entered the programme, which started with an e-learning lecture on focus cardiac ultrasound, with practice on a simulator, followed by implementation on patients, and ended with self-training in image analysis on an online platform. A post-test evaluation was carried out at the end of the theoretical training, followed by a final live evaluation on patients (timed acquisition of the five reference views used in focus cardiac ultrasound, grading each view on a scale of 1 to 5). Trainees were also evaluated online regarding their interpretation of 20 video clips. The median (interquartile range) interpretability scores following simulator training were 5 (4-5) for the parasternal long-axis view, 5 (4-5) for the apical four-chamber view, and 4 (4-5) for the subcostal window. Interpretability was significantly inferior in the live evaluation compared with the post-test evaluation, except for the parasternal long-axis and subcostal views. The mean score for the video clips (out of 20) was 14.5±2.4. After a short self-training programme, trainees were able to acquire the main views of focus cardiac ultrasound with sufficient quality and in a short time period.

Data-driven ontology generation and evolution towards intelligent service in manufacturing systems

Abstract To support intelligent manufacturing, providing a unified production data view by integrating distributed data collected by different enterprise information systems is critical. Because various information systems are often heterogeneous, ontology is widely adopted to present a global reference view for data integration. However, construction and maintenance of these ontologies is difficult because of the heterogeneity and dynamism of these large-scale data. In this paper, with the objective of intelligent manufacturing application implementation, we propose a comprehensive ontology generation and evolution method that automatically abstracts ontology from raw production data and dynamically adjusts the ontology in accordance with changes in the manufacturing data environment. The proposed method comprises four phases: data extraction, ontology construction, ontology connection, and ontology evolution. In the first phase, data from different sources are mapped to data entities to form a unified data structure. In the second phase, an initial ontology is generated via instance-driven ontology construction. In the third phase, to support intelligent manufacturing, the initial ontologies are organised in terms of the dimensions of the various business elements, such as stuff, machine, product, process, and scenarios. In the fourth phase, rules regarding ontology restrictions are formulated to realise ontology evolution that respond to changes in the manufacturing environment. To verify the efficacy of the proposed method, a prototype was implemented with real data from a manufacturing factory, in which the constructed ontology was used as the metadata of product data in intelligent manufacturing.

Is E-FAST possible and useful on the battlefield? A feasibility study during medical courses in hostile environment (MEDICHOS): preliminary results

IntroductionThe extent of the French forces’ territory in the Sahel band generates long medical evacuations. In case of many victims, to respect the golden hour rule, first-line sorting is essential....

Artifact Handling Based on Depth Image for View Synthesis

The depth image based rendering (DIBR) is a popular technology for 3D video and free viewpoint video (FVV) synthesis, by which numerous virtual views can be generated from a single reference view and its depth image. However, some artifacts are produced in the DIBR process and reduce the visual quality of virtual view. Due to the diversity of artifacts, effectively handling them becomes a challenging task. In this paper, an artifact handling method based on depth image is proposed. The reference image and its depth image are extended to fill the holes that belong to the out-of-field regions. A depth image preprocessing method is applied to project the ghosts to their correct place. The 3D warping process is optimized by an adaptive one-to-four method to deal with the cracks and pixel overlapping. For disocclusions, we calculate depth and background terms of the filling priority based on depth information. The search for the best matching patch is performed simultaneously in the reference image and the virtual image. Moreover, adaptive patch size is used in all hole-filling processes. Experimental results demonstrate the effectiveness of the proposed method, which has better performance compared with previous methods in subjective and objective evaluation.

Multiview‐coherent disocclusion synthesis using connected regions optimization

AbstractHandling of missing areas is a key step for depth‐based rendering to synthesize virtual views. Existing methods usually consider finding candidate pixels from only one reference view to fill missing areas. However, the information provided by one reference view is restricted by the position of the view. By utilizing two reference views located on both the left and right sides of the virtual view, we propose to synthesize the missing areas at hole level with connected regions optimization. To avoid the appearance of ghost boundary, we apply morphological operations to generate a boundary band map for the depth map, which restricts the warping of the virtual view. We use a binary map to mark unknown pixels in a hole, label the connected unknown regions, and count the area of each connected region, which decide the order in our enhanced inpainting synthesis. Besides, we separate the foreground and background regions of the depth map to constrain the searching of candidate pixels. Multiple experiments on virtual view synthesis have shown the effectiveness and high quality of our multiview‐coherent disocclusion synthesis.

Fast and high-quality virtual view synthesis from multi-view plus depth videos

Depth image based rendering (DIBR) is an effective method for virtual view synthesis from Multi-view Plus Depth(MVD) video. Synthetic images, however, often contain ghost effect and some holes of varying sizes. This paper uses color correction of reference views, and combines depth-based image fusion with direct color image fusion to decrease the ghost effect. Meanwhile, the cracks are filled using depth filtering and inverse warping. What’s more, the image depth-aided inpainting with GPU acceleration is used to fill the remaining big disocclusions. Experimental results show that our proposed method improved the quality of virtual view synthetic images and reduced the processing time sharply.