基于改进随机蕨的跟踪注册方法研究

针对无标识增强现实跟踪注册方法在复杂环境下存在跟踪注册失败、速度较慢的问题,提出一种基于改进随机蕨的无标识增强现实跟踪注册方法。该方法以真实场景中的目标物体图像作为模板,使用随机蕨分类器进行目标检测,解决环境光照变化或目标被遮挡跟踪注册失败的问题。使用FAST角点进行特征检测提升检测速度,对随机蕨的仿射过程进行改进来弥补特征点尺度不变性和仿射不变性缺失。通过该分类器进行特征匹配,进而估计三维位姿并渲染注册虚拟物体。实验结果证明,该方法具有较好的准确性、实时性和鲁棒性。     

基于机器学习的自然特征匹配方法

针对增强现实中的三维注册问题,提出一种基于机器学习的图像自然特征点识别方法。基于高斯混合模型进行样本选择,利用模式识别中的分类方法替代特征向量的最近邻匹配,将计算负担从实时阶段转移到训练阶段,利用各匹配点对之间的相似度计算核密度估计的权值,实现相关平面目标的跟踪。实验结果表明,该方法实时性好、相机位姿估计精确,对光照、遮挡、透视等变化具有较强的鲁棒性。     

Android的无标识增强现实注册算法实现

为了克服传统增强现实技术的局限性,在Android系统上实现了基于无标识增强现实注册算法.使用ORB和强制匹配算法对特征点进行检测、描述和匹配,再使用RANSAC算法计算单应性矩阵并对匹配结果进行优化,然后计算摄像头位姿并进行滤波处理,最后将三维模型注册到真实场景中,达到了虚实融合的效果.实验结果表明,算法结合Android NDK编程和多线程技术,注册准确,性能较好,能够达到实时的要求,而且在光照和距离发生变化、标志被部分遮挡的情况下鲁棒性较好,克服了传统增强现实技术的局限性,具有一定的研究价值.     

基于KCF与改进ORB的增强现实方法

针对增强现实(AR)系统在进行虚拟信息叠加时待注册区域被遮挡的情况,提出一种基于实时特征检测与目标跟踪的AR系统三维注册方法。使用KCF算法对待注册目标区域与模板进行实时FAST特征匹配,通过改进ORB算法,提出SIFT-ORB-MRANSAC融合算法,完成特征点的提取、匹配以及误匹配去除。在此基础上,根据特征点之间的匹配关系计算注册矩阵,通过注册矩阵叠加虚拟信息实现对现实世界的增强。实验结果表明,该方法在光照变化、遮挡以及旋转变换的情况下,可将虚拟信息快速、准确地叠加到待注册区域,提高AR系统的运算效率。     

基于粒子滤波和压缩感知的目标跟踪算法

为了解决目标跟踪过程中出现的目标遮挡和光照变化问题,提出一种基于粒子滤波和压缩感知的目标跟踪算法。算法融合颜色特征和纹理特征来描述目标,增强算法在光照变化和复杂环境下的鲁棒性;利用压缩感知理论对特征进行降维,提高算法实时性;最后,根据粒子滤波原理估计目标状态,得到目标位置。实验结果表明,本算法在有效减少算法运行时间的前提下,能够准确跟踪遮挡和光照变化情况下的目标。     

改进的交互式多模型跟踪算法

针对传统交互式多模型算法实行正则滤波的单一化缺点,提出一种改进的跟踪算法。利用卡尔曼滤波匹配系统线性部分,粒子滤波匹配非线性部分,根据匹配深度判断目标遮挡程度,当目标被严重遮挡时,采用迭代的多级粒子滤波方法进行重采样,并结合卡尔曼滤波更新模型概率。实验结果表明,该算法实时性强,能提高模型滤波速度和目标状态的估计精度,缩短计算时间,解决跟踪过程中的遮挡问题。     

面向增强现实的多传感器组合位姿注册算法

持续稳定的准确注册是构建增强现实系统的关键,为提高跟踪注册的稳定性和精度,提出了一种基于互补滤波(CF)和无迹卡尔曼滤波(UKF)的多传感器融合注册方案.该算法采用互补滤波器融合陀螺仪、加速度计和地磁感应计数据估计摄像头姿态;在处理视觉图像时,结合惯性姿态数据进行图像特征匹配;利用UKF融合视觉和惯性数据进行摄像头位置估计.实验表明:该算法在跟踪稳定性、精度、效率和抗干扰能力均优于传统的基于扩展卡尔曼滤波(EKF)的融合算法.     

基于KCF的样本更新与目标重定位方法

为了解决核相关滤波（Kernelized Correlation Filter, KCF）算法由于测量误差的累积导致目标跟踪失败的问题,提出一种样本质量评价机制,筛选样本对分类器进行更新操作。为了解决目标遮挡后重定位的问题,使用Kalman滤波算法估计目标位置,然后评价其估计结果。为了解决目标位置难以预测的问题,使用ORB特征点匹配算法完成目标的重新定位。在TB数据集中选取部分序列进行测试。实验结果表明,目标出现短时间、长时间遮挡时,改进算法在精确度和成功率上都有一定程度的提高。     

抗遮挡与尺度自适应的改进KCF跟踪算法

核相关滤波(kernel correlation filter,KCF)目标跟踪算法在目标发生尺度变化或受长时间遮挡时无法实现准确跟踪.对此,提出一种融合窗口滤波的抗遮挡尺度自适应的目标跟踪算法.首先,利用快速尺度估计对跟踪目标进行尺度变换;然后,当检测到目标受到遮挡时停止对分类器模型的更新,融合加权窗口滤波器对目标位...     

基于融合特征的多尺度快速相关滤波跟踪算法

针对复杂场景下目标遮挡和尺度变化所导致的跟踪效果不佳问题,提出一种基于融合特征的多尺度快速相关滤波跟踪算法。首先,对目标的3种特征降维融合构成特征矩阵;其次,采用主成分分析思想实时地提取显著特征,重构特征矩阵,在有效降维的同时训练位置相关滤波器;最后,利用融合特征矩阵训练尺度相关滤波器,从而准确预测目标位置和尺度。实验部分将改进算法与目前流行的相关滤波跟踪算法进行比较,结果表明,改进算法在目标遮挡和尺度变化场景下跟踪精度较高,平均跟踪速度达到52.5 frame/s。     

A Tracking Registration Method for Augmented Reality Based on Multi-modal Template Matching and Point Clouds

In order to overcome the defects where the surface of the object lacks sufficient texture features and the algorithm cannot meet the real-time requirements of augmented reality, a markerless augmented reality tracking registration method based on multimodal template matching and point clouds is proposed. The method first adapts the linear parallel multi-modal LineMod template matching method with scale invariance to identify the texture-less target and obtain the reference image as the key frame that is most similar to the current perspective. Then, we can obtain the initial pose of the camera and solve the problem of re-initialization because of tracking registration interruption. A point cloud-based method is used to calculate the precise pose of the camera in real time. In order to solve the problem that the traditional iterative closest point (ICP) algorithm cannot meet the real-time requirements of the system, Kd-tree (k-dimensional tree) is used under the graphics processing unit (GPU) to replace the part of finding the nearest points in the original ICP algorithm to improve the speed of tracking registration. At the same time, the random sample consensus (RANSAC) algorithm is used to remove the error point pairs to improve the accuracy of the algorithm. The results show that the proposed tracking registration method has good real-time performance and robustness.

     

基于改进KCF的跟踪注册方法

针对三维注册易受环境以及目标跟踪检测算法耗时严重、精度低的影响,提出改进KCF(I KCF)的跟踪注册方法。该方法分为4步：（1)利用正则最小二乘分类器的样本训练来获取尺度核相关滤波器和位置信息;（2)搜索尺度核相关滤波器和位置输出响应最大值,完成尺度和目标位置的检测;（3)借鉴MOSSE跟踪器更新方法对模型更新;（4)采用ORB算法对目标位置特征检测并计算出注册矩阵。选取视觉跟踪基准数据集中的6组数据以及拍摄的视频序列仿真实验。仿真结果表明,当目标位置发生旋转、缩放、部分遮挡、光照和运动模糊时,I KCF在精确度、成功率以及效率上总体优于KCF、TLD、Struck和CT算法;且目标位置与OpenGL立方体注册融合度较高;基于I KCF的AR系统具有较好的实时性、稳定性和鲁棒性。     

基于Kinect的点云配准方法

Kinect采集的点云存在点云数量大、点云位置有误差,直接使用迭代最近点(ICP)算法对点云进行配准时效率低.针对该问题,提出一种基于特征点法向量夹角的改进点云配准算法.首先使用体素栅格对Kinect采集的原始点云进行下采样,精简点云数量,并使用滤波器移除离群点.然后使用SIFT算法提取目标点云与待配准点云公共部分的特征点,通过计算特征点法向量之间的夹角调整点云位姿,完成点云的初始配准.最后使用ICP算法完成点云的精细配准.实验结果表明,该算法与传统ICP算法相比,在保证点云配准精度的同时,能够提高点云的配准效率,具有较高的适用性和鲁棒性.     

A Geometry-Based Point Cloud Reduction Method for Mobile Augmented Reality System

In this paper, a geometry-based point cloud reduction method is proposed, and a real-time mobile augmented reality system is explored for applications in urban environments. We formulate a new objective function which combines the point reconstruction errors and constraints on spatial point distribution. Based on this formulation, a mixed integer programming scheme is utilized to solve the points reduction problem. The mobile augmented reality system explored in this paper is composed of the offline and online stages. At the offline stage, we build up the localization database using structure from motion and compress the point cloud by the proposed point cloud reduction method. While at the online stage, we compute the camera pose in real time by combining an image-based localization algorithm and a continuous pose tracking algorithm. Experimental results on benchmark and real data show that compared with the existing methods, this geometry-based point cloud reduction method selects a point cloud subset which helps the image-based localization method to achieve higher success rate. Also, the experiments conducted on a mobile platform show that the reduced point cloud not only reduces the time consuming for initialization and re-initialization, but also makes the memory footprint small, resulting a scalable and real-time mobile augmented reality system.     

航空叶片打磨余量分析及轨迹生成

针对航空发动机叶片打磨加工前,叶身余量分布不均且较小的问题,提出一种基于毛坯点云配准的加工余量分析和自适应打磨轨迹生成方法。利用精确扫描测绘技术获取毛坯三维点云,形成了毛坯/零件数模二者点云配准方法;通过基准对齐、点云轮廓包含等条件约束,实现了毛坯三维加工余量分析;在余量分布点云基础上,通过截面获取加工点云轨迹,对轨迹点云进行珠链排序,将轨迹排序点有效化,计算出连续合适的打磨路径,实现自适应余量打磨。最后在Vericut软件中进行了打磨仿真,验证了提出方法的有效性。     

Intelligent LIDAR scanning region selection for satellite pose estimation

This paper proposes a method to select a near-optimal laser scanning area on a target body that will result in the best registration accuracy. The method is based on constraint analysis and employs a sensitivity index which is used as a registration accuracy predictor. It is shown that point cloud configurations with higher values of this index return more accurate pose estimates than unstable configurations with lower index values. Iterative Closest Point (ICP) registration tests are conducted on four satellite geometries using synthetic range data. The proposed method can be used to increase the accuracy of ICP registration and to reduce registration processing time.     

Sensor fusion based head pose tracking for lightweight flight cockpit systems

Flight cockpit head tracking systems (HTS) are one of the most important impetuses for head pose tracking in the field of augmented reality. For the purpose of implementing the natural interaction between pilot and the complete internal environment in our lightweight flight cockpit system, a head tracking system consisting of inside-out tracking (IOT) and outside-in tracking (OIT) is designed and a novel approach using sensor fusion is proposed to dynamically track pilot’s head pose. The proposed approach utilizes a sensor fusion framework, composed of extended Kalman filters and fusion filter, to fuse the poses from complementary IOT and OIT. An experimental setup is established to simulate the cockpit HTS and verify the proposed approach. Experimental results show that the proposed tracking scheme based on sensor fusion is capable of achieving more accurate and stable pose outputs, extending tracking range as well as better robustness compared with single IOT or OIT.     

Multi-sensor based real-time 6-DoF pose tracking for wearable augmented reality

Wearable augmented reality (WAR) combines a live view of a real scene with computer-generated graphic on resource-limited platforms. One of the crucial technologies for WAR is a real-time 6-DoF pose tracking, facilitating registration of virtual components within in a real scene. Generally, artificial markers are typically applied to provide pose tracking for WAR applications. However, these marker-based methods suffer from marker occlusions or large viewpoint changes. Thus, a multi-sensor based tracking approach is applied in this paper, and it can perform real-time 6-DoF pose tracking with real-time scale estimation for WAR on a consumer smartphone. By combining a wide-angle monocular camera and an inertial sensor, a more robust 6-DoF motion tracking is demonstrated with the mutual compensations of the heterogeneous sensors. Moreover, with the help of the depth sensor, the scale initialization of the monocular tracking is addressed, where the initial scale is propagated within the subsequent sensor-fusion process, alleviating the scale drift in traditional monocular tracking approaches. In addition, a sliding-window based Kalman filter framework is used to provide a low jitter pose tracking for WAR. Finally, experiments are carried out to demonstrate the feasibility and robustness of the proposed tracking method for WAR applications.     

基于改进的核相关滤波器的长期目标跟踪算法

针对核相关滤波器跟踪算法在视觉目标跟踪中因遮挡产生的目标丢失后，无法重新准确地跟踪目标问题，提出一种基于GM(1,1)灰色预测模型和间隔性模板匹配的改进的核相关滤波器跟踪算法。实验结果表明，在复杂环境下，所提出的改进算法与传统的核相关滤波器目标跟踪算法相比，综合性能有很大的提高，与其他跟踪算法相比也有一定的优势。     

基于自适应跟踪窗的红外小目标跟踪方法

针对采用固定跟踪窗的传统跟踪方法容易将云层边角等干扰信息纳入跟踪窗,从而影响目标稳定跟踪的问题,提出了一种自适应跟踪窗的算法。在检测到目标的前提下,通过Kalman滤波器动态地改变目标跟踪过程中跟踪窗的大小,以减少跟踪过程中云层等干扰信息对跟踪的影响,并减少算法需要处理的信息量。在真实红外跟踪平台上的实验表明,提出的算法在干扰抑制和运行速度方面都有一定程度的提高。