3D Track-keeping Method for Autonomous Underwater Vehicle

In this paper, 3D track-keeping control method for autonomous underwater vehicle (AUV) with and without the influence of ocean current is investigated. Because the system to be controlled is highly nonlinear and strong coupled, an approach is used to divide it into two subsystems. One is to control the heading and the track error on the horizontal plane. The other is to control the pitch and the track error on the vertical plane. The results of computer simulation show that the autopilot works properly, it can capture the current waypoint and turns to track the next path automatically.

Investigation of Inside-Out Tracking Methods for Six Degrees of Freedom Pose Estimation of a Smartphone in Augmented Reality

Six degrees of freedom(6DoF)input interfaces are essential formanipulating virtual objects through translation or rotation in three-dimensional(3D)space.A traditional outside-in tracking controller requires the installation of expensive hardware in advance.While inside-out tracking controllers have been proposed,they often suffer from limitations such as interaction limited to the tracking range of the sensor(e.g.,a sensor on the head-mounted display(HMD))or the need for pose value modification to function as an input interface(e.g.,a sensor on the controller).This study investigates 6DoF pose estimation methods without restricting the tracking range,using a smartphone as a controller in augmented reality(AR)environments.Our approach involves proposing methods for estimating the initial pose of the controller and correcting the pose using an inside-out tracking approach.In addition,seven pose estimation algorithms were presented as candidates depending on the tracking range of the device sensor,the tracking method(e.g.,marker recognition,visual-inertial odometry(VIO)),and whether modification of the initial pose is necessary.Through two experiments(discrete and continuous data),the performance of the algorithms was evaluated.The results demonstrate enhanced final pose accuracy achieved by correcting the initial pose.Furthermore,the importance of selecting the tracking algorithm based on the tracking range of the devices and the actual input value of the 3D interaction was emphasized.

基于改进蝴蝶优化算法的无人机3-D航迹规划方法

针对基本蝴蝶优化算法(Butterfly optimization algorithm,BOA)在进行无人机(Unmanned aerial vehicle,UAV)三维航迹规划时存在的搜索速度慢、搜索精度低以及易陷入局部最优等问题,提出一种改进的蝴蝶优化算法(Improved butterfly optimization algorithm,IBOA)。在全局搜索阶段提出对数自适应惯性权重策略和动态更新调节策略,提高了算法全局搜索能力和搜索精度。同时,在局部搜索阶段,提出一种动态概率余弦选择策略,增加位置更新多样性,避免陷入局部最优。首先,为检验改进算法与基本算法的寻优性能,在部分标准多元函数上进行仿真对比。对比结果表明,改进算法对复杂函数具有较强的寻优能力,能在更短时间内找到全局最优解。然后,在二维路径规划仿真中对比了改进算法与PSO算法性能,从对比结果看,IBOA具有更优的规划效果。接着,利用山峰模拟函数对UAV三维航迹规划进行建模,将改进算法应用到航迹规划中,利用MATLAB仿真对比了不同复杂度环境下的航迹规划效果。仿真实验表明:相同实验条件下,该优化算法较BOA综合适应度值减小21.9%,具有搜索速度快、搜索精度高等优点,能够有效地指导UAV在三维环境中完成自主导航避障任务。

Novel learning framework for optimal multi-object video trajectory tracking

Background With the rapid development of Web3D, virtual reality, and digital twins, virtual trajectories and decision data considerably rely on the analysis and understanding of real video data, particularly in emergency evacuation scenarios. Correctly and effectively evacuating crowds in virtual emergency scenarios are becoming increasingly urgent. One good solution is to extract pedestrian trajectories from videos of emergency situations using a multi-target tracking algorithm and use them to define evacuation procedures. Methods To implement this solution, a trajectory extraction and optimization framework based on multi-target tracking is developed in this study. First, a multi-target tracking algorithm is used to extract and preprocess the trajectory data of the crowd in a video. Then, the trajectory is optimized by combining the trajectory point extraction algorithm and Savitzky-Golay smoothing filtering method. Finally, related experiments are conducted, and the results show that the proposed approach can effectively and accurately extract the trajectories of multiple target objects in real time. Results In addition, the proposed approach retains the real characteristics of the trajectories as much as possible while improving the trajectory smoothing index, which can provide data support for the analysis of pedestrian trajectory data and formulation of personnel evacuation schemes in emergency scenarios. Conclusions Further comparisons with methods used in related studies confirm the feasibility and superiority of the proposed framework.

Research on 3D Target Pose Tracking and Modeling

This paper tackles pose tracking and model refinement, one of the fundamental work for 3D photogrammetry. The researches belong to the videometrics, an interdisciplinewhich combines computer vision, digital image processing, photogrammetry and optical measurement. Related works are summarized briefly in this paper. This paper studies the problem of pose tracking for target with 3D model. For the target with accurate 3D model, line model based pose tracking methods are proposed for target which is rich in line features. Experimental results indicate that the proposed methods track the target pose accurately. Normal distance iterative reweighted least squares and distance image iterative least squares methods are proposed to process more general targets. This paper adopts bundle adjustment to tackle pose tracking in image sequence for target with inaccurate 3D line model. The proposed method optimizes the model line parameters and the pose parameters simultaneously. The model line orientation, position and mean angle error, mean position error of the pose are 0.3°,3.5 mm and 0.12°,20.1 mm in simulation experiments of satellite pose tracking. Line features are used to track target pose with unknown 3D model through image sequence. The model line parameters and pose parameters are optimized under the framework of SFM. In simulation experiments, the reconstructed line orientation, position error and mean angle error, mean position error of pose are 0.4°,7.5 mm and 0.16°,23.5 mm.

基于双线性ADRC的翼伞系统三维航迹跟踪控制

目前翼伞系统的航迹跟踪主要针对二维路径,对于三维航迹跟踪的研究不多。针对翼伞系统6-DOF模型,采用具有天然解耦属性的自抗扰控制策略,设计一种基于双线性ADRC(B-ADRC)的三维轨迹跟踪控制方法。在水平面与纵向设计制导率与控制器,实现姿态与轨迹位置的跟踪,并对轨迹跟踪误差进行实时修正。跟踪过程中,将理想轨迹离散化获得一系列参考点,通过点切换的方式实现了复杂轨迹的跟踪。实验结果表明:所设计的双线性ADRC控制器能够实现对三维航迹的跟踪,具有良好的鲁棒性和抗干扰能力。

A review of edge-based 3D tracking of rigid objects

Three-dimensional(3D)tracking of rigid objects plays a very important role in many areas such as augmented reality,computer vision,and robotics.Numerous works have been done to pursue more stable,faster,and more accurate 3D tracking.Among various tracking methods,edge-based 3D tracking has been widely used owing to its many advantages.Furthermore,edge-based methods can be mainly divided into two categories,methods without and those with explicit edges,depending on whether explicit edges need to be extracted.Based on this,representative methods in both categories are introduced,analyzed,and compared in this paper.Finally,some suggestions on the choice of methods in different application scenarios and research directions in the future are given.

3D Characterization of corneal deformation using ultrasound speckle tracking

The three-dimensional(3D)mechanical response of the cornea to intraocular pressure(IOP)elevation has not been previously reported.In this study,we use an ultrasound speckle tracking technique to measure the 3D displacements and strains within the central 5.5 mm of porcine corneas during the whole globe infation.Infation tests were performed on dextran-treated corneas(treated with a 10%dextran solution)and untreated corneas.The dextran-treated corneas showed an inflation response expectod of a thin spherical shell,with through-thickness thinning and in-plane stretch,although the strain magnitudes exhibited a heterogeneous spatial distribution from the central to more peripheral cornea.The untreated eyes demon-strated a response consistent with swelling during experimentation,w ith through-thickness expansion overriding the infation response.The average volume ratios obtained in both groups was near 1 confirming general incompresibility,but local regions of volume loss or expansion were observed.These results suggest that biomechanical measurements in 3D provide important new insight to understand the mechanical response of ocular tissues such as the cornea.

RFID-based 3D human pose tracking: A subject generalization approach

Three-dimensional (3D) human pose tracking has recently attracted more and more attention in the computer vision field. Real-time pose tracking is highly useful in various domains such as video surveillance, somatosensory games, and human-computer interaction. However, vision-based pose tracking techniques usually raise privacy concerns, making human pose tracking without vision data usage an important problem. Thus, we propose using Radio Frequency Identification (RFID) as a pose tracking technique via a low-cost wearable sensing device. Although our prior work illustrated how deep learning could transfer RFID data into real-time human poses, generalization for different subjects remains challenging. This paper proposes a subject-adaptive technique to address this generalization problem. In the proposed system, termed Cycle-Pose, we leverage a cross-skeleton learning structure to improve the adaptability of the deep learning model to different human skeletons. Moreover, our novel cycle kinematic network is proposed for unpaired RFID and labeled pose data from different subjects. The Cycle-Pose system is implemented and evaluated by comparing its prototype with a traditional RFID pose tracking system. The experimental results demonstrate that Cycle-Pose can achieve lower estimation error and better subject generalization than the traditional system.

THREE-IMAGE MATCHING FOR 3-D LINEAR OBJECT TRACKING

This paper will discuss strategies for trinocular image rectification and matching for linear object tracking.It is well known that a pair of stereo images generates two epipolar images.Three overlapped images can yield six epipolar images in situations where any two are required to be rectified for the purpose of image matching.In this case,the search for feature correspondences is computationally intensive and matching complexity increases.A special epipolar image rectification for three stereo images,which simplifies the image matching process,is therefore proposed.This method generates only three rectified images,with the result that the search for matching features becomes more straightforward.With the three rectified images,a particular line_segment_based correspondence strategy is suggested.The primary characteristics of the feature correspondence strategy include application of specific epipolar geometric constraints and reference to three_ray triangulation residuals in object space.

An Analysis on Position Estimation, Drifting and Accumulated Error Accuracy during 3D Tracking in Electronic Handheld Devices

This work focuses on a brief discussion of new concepts of using smartphone sensors for 3D painting in virtual or augmented reality. Motivation of this research comes from the idea of using different types of sensors which exist in our smartphones such as accelerometer, gyroscope, magnetometer etc. to track the position for painting in virtual reality, like Google Tilt Brush, but cost effectively. Research studies till date on estimating position and localization and tracking have been thoroughly reviewed to find the appropriate algorithm which will provide accurate result with minimum drift error. Sensor fusion, Inertial Measurement Unit (IMU), MEMS inertial sensor, Kalman filter based global translational localization systems are studied. It is observed, prevailing approaches consist issues such as stability, random bias drift, noisy acceleration output, position estimation error, robustness or accuracy, cost effectiveness etc. Moreover, issues with motions that do not follow laws of physics, bandwidth, restrictive nature of assumptions, scale optimization for large space are noticed as well. Advantages of such smartphone sensor based position estimation approaches include, less memory demand, very fast operation, making them well suited for real time problems and embedded systems. Being independent of the size of the system, they can work effectively for high dimensional systems as well. Through study of these approaches it is observed, extended Kalman filter gives the highest accuracy with reduced requirement of excess hardware during tracking. It renders better and faster result when used in accelerometer sensor. With the aid of various software, error accuracy can be increased further as well.

A Graphic Algorithm of＂Track＂ Effect in 3D Games

In 3D games, a lot of weapons in the movement will drag a ＂follow the shadow＂ effect, which is called the ＂track＂. In this paper, we first analyze the change rule of the ＂track＂, and then put forward a kind of algorithm to realize the ＂track＂. The calculation of this algorithm is small, but the effect is very real, has been successfully applied to a variety of 3D games.

三维模型与视频素材的完美结合——AE插件Element 3D与Track camera技术的实际应用

相较于传统的AE针对3D动画合成中出现的各种繁琐的操作,如摄像机同步、光影匹配等等,Element 3D都可以让特效师直接在AE里完成,而不需要考虑摄像机和光影迁移等诸多问题。配合AE内置的Tracker camera功能,更是可以完成各类复杂的三维后期合成特效,大大降低了以往摄像机反求搭建三维场景的难度和渲染负担。

数字立体影像2D转制3D新技术应用研究

最近,基于Roto-Tracking及图像边缘处理等技术的数字立体影像2D转制3D新技术方式逐渐进入到数字立体影像的工作流程中。这种技术有别于传统主流的2D转制3D技术,有其独特的优势和特点。在处理画面细节较为复杂部分的深度信息时,有很高的效率,并且有较好的精度保障。本研究将其与传统主流的2D转制3D技术进行对比,理性分析新技术应用的优势和前景。

基于特征点的3D人脸姿态跟踪

针对视频序列中的人脸跟踪问题,提出一种单摄像头的人脸3D姿态跟踪方法。利用SIFT特征点匹配算法来得到可靠的帧间特征匹配。将前帧与所选的关键帧特征匹配信息及融入到对当前的姿态估计中,利用SIFT特征点匹配算法来得到可靠的帧间特征匹配。最后通过利用RANSAC随机选取特征点对,并用POSIT和最小化误差组合的3D投影方法以迭代的方式得到精确的当前帧人脸姿态估计。通过多组实验数据对比,表明了该算法在严重遮挡、头部摆动幅度较大、匹配点较少的复杂情况干扰下仍具有鲁棒性,并且解决了3D人脸跟踪的漂移问题,实现对目标人脸的稳定跟踪,对比以往2D跟踪算法在复杂环境下具有明显的改善。

Survey of 3D modeling using depth cameras

Three-dimensional(3D)modeling is an important topic in computer graphics and computer vision.In recent years,the introduction of consumer-grade depth cameras has resulted in profound advances in 3D modeling.Starting with the basic data structure,this survey reviews the latest developments of 3D modeling based on depth cameras,including research works on camera tracking,3D object and scene reconstruction,and high-quality texture reconstruction.We also discuss the future work and possible solutions for 3D modeling based on the depth camera.

Three-Dimensional Discrete Observability Analysis for Air-to-Air Missile Target Tracking

The interception information of infrared（ IR）-guided air-to-air missiles（ AAM） is mainly estimated only using the basic bearing measurements. In order to intercept highly maneuverable targets,it is essential to study the system observability to improve the target tracking system performance.The uniqueness of this paper is that the observability analysis is derived based on a discrete three-dimensional （3D） system model. During the maneuvering scenario,the system is approximated by a segment-by-segment system. The relationship between missile-target motion and observability is given by direct and dual approaches. Meanwhile sufficient observability conditions are derived. Moreover,a numerical simulation is conducted and an alternate method is provided to reinforce the proposed observability analysis results.

Hand gesture tracking algorithm based on visual attention

In the majority of the interaction process, the operator often focuses on the tracked 3D hand gesture model at the ＂interaction points＂ in the collision detectionscene, such as ＂grasp＂ and ＂release＂ and objects in the scene, without paying attention to the tracked 3D hand gesture model in the total procedure. Thus in this paper, a visual attention distribution model of operator in the ＂grasp＂, ＂translation＂, ＂release＂ and other basic operation procedures is first studied and a 3D hand gesture tracking algorithm based on this distribution model is proposed. Utilizing the algorithm, in the period with a low degree of visual attention, a pre-stored 3D hand gesture animation can be used to directly visualise a 3D hand gesture model in the interactive scene; in the time period with a high degree of visual attention, an existing ＂frame-by-frame tracking＂ approach can be adopted to obtain a 3D gesture model. The results demonstrate that the proposed method can achieve real-time tracking of 3D hand gestures with an effective improvement on the efficiency, fluency, and availability of 3D hand gesture interaction.

MetraSCAN3D TM光学三坐标3D扫描系统

无臂手持式MetraSCAN3D“光学三坐标3D扫描仪和C．Track TM双摄像头传感器形成了一个独特的组合，确保在实验室和工作场所能生成最精确的测量值。结合HandyPROBE TM，

基于3D建模和射线跟踪算法的5G室内深度覆盖预测方法研究

由于5G室内覆盖的方案设计过程中,有着较高的复杂性,同时也具有着多样性的特征,因此就使得在运行的过程中,5G室内覆盖的效果难以进行准确的预测。因此,在分析过程中,就着重针对3D建模以及射线跟踪算法下,对其5G舍内深度覆盖进行预测方法的分析和研究,以此帮助相关领域的工作人员进行研究。