增强现实环境下的CPS虚拟装配系统研究与实现

基于双目视觉原理，利用Unity3D游戏引擎开发了一种增强现实环境下的信息物理融合(cyber-physical systems, CPS)虚拟装配系统。通过研究快速定位算法识别特征标记点建立虚拟模型与实物装配单元的配准关系，融合虚拟模型投影图像与实物装配体图像实现虚拟装配仿真，实时输出在视频眼镜结构中显示。经过试验验证，该系统满足CPS实时性、稳定性以及信息世界与物理世界融合的要求。     

增强现实系统虚实亮度评价方法研究

在增强现实系统中,虚拟物体与真实环境之间具有相匹配的亮度关系,会使虚实融合达到逼真的效果。为了获得虚实物体的亮度匹配,根据图像亮度处理的原理,对增强现实系统的虚实环境提出了整体和局部两种亮度评价算法,并对新型光学透视式头盔显示器的亮度匹配算法进行了改进,提高了系统效率。实验结果表明,对在不同情况下的真实环境和虚拟物体来说,这两种算法各有其优点,调节后的结果是理想的。     

Motion blur parameters estimation for image restoration

This paper deals with estimation of parameters for motion blurred images. The objectives are to estimate the length (L) and the blur angle (θ) of the given degraded image as accurately as possible so that the restoration performance can be optimised. Gabor filter is utilized to estimate the blur angle whereas a trained radial basis function neural network (RBFNN) estimates the blur length. Once these parameters are estimated the conventional restoration is performed. To validate the proposed scheme, simulation has been carried out on standard images as well as in real images subjected to different blur angles and lengths. The robustness of the scheme is also validated in noise situations of different strengths. In all situations, the results have been compared with standard schemes. It is in general observed that the proposed scheme outperforms its counterparts in terms of restoration parameters and visual quality.     

用于增强现实的头盔显示器的设计

穿透式双通道头盔显示器 (HMD)是增强现实系统中的关键部件。本文给出了一种新颖的穿透式双通道头盔显示器的设计方案 ,使得当在用于增强现实系统中时 ,能够获得更大的透过率 ,以获得清晰的外部世界与内部产生的场景信息。同时通过成功的光学设计 ,获得了大视场、高分辨率的光学系统     

折/衍混合增强现实头盔显示器光学系统设计

利用衍射光学元件独有的负色散性质和可实现光波面任意相位调制的特点 ,在光学系统中引入衍射面 ,设计了出瞳距离为 2 6mm ,出瞳直径为 12mm ,视场角为 2 0°(H)× 15 .4°(V)的用于增强现实的折 /衍混合穿透式双通道头盔显示器的光学系统。设计的系统内、外两个光通道的光能量利用率分别达到 1/4和 1/2。系统分辨力适合采用分辨率为 80 0× 6 0 0、像元尺寸为 33μm的图像源。设计结果 ,系统镜头直径小于 4 6mm ,满足用于双目显示的要求。设计结果表明 ,该系统不仅在结构上满足使用者因素的要求 ,而且成像质量接近衍射极限 ,具有很高的分辨率 ,色差和畸变非常小。设计结果完全满足用于增强现实的要求。     

倒谱在混合模糊图像分析中的应用

降晰参数识别在模糊图像恢复过程中具有很重要的作用。在各种图像捕获系统中,有两种形式的图像模糊比较常见:一种是由光学系统散焦造成的散焦模糊;另一种是物体与照相机之间的相对运动造成的运动模糊。相对单个模糊模型的参数识别来说,混合了散焦和运动模糊的图像,其模糊参数的识别要复杂得多。许多识别方法一般都是用来分析某一特定的模糊模型的,而对两种模糊混合在一起的情况来说是很难区分的。提出了一种倒谱分析方法,在倒谱域同时对这两种模型参数进行识别。在分析过程中,仍需要利用这两种模糊模型在频域的特征,首先应用一些调整性的变换,然后再转换到倒谱域,以便更准确地评估模糊参数。     

Custom made wireless systems for interactive footstep sounds synthesis

This paper describes both the hardware and software development of three custom made wireless systems used for the interactive synthesis of footstep sounds. The data collected from the detection of the feet movements of a walker are used for real-time control of physical models for the auditory display of different ground textures and shoe types. The first system is based on a wooden plank under which an array of microphones is placed. The second system exploits the motion capture technology. The third system consists of a pair of sandals enhanced with two force sensitive resistors and two 3-axes accelerometers for each shoe. The characteristics of the three architectures are discussed and compared. The developed locomotion interfaces find application in several contexts, such as augmented reality, virtual reality, or entertainment, as well as in perceptual studies investigating the influence of interactive sounds on locomotion performance usable for training and rehabilitation purposes.     

Dynamic modulation transfer function: a method to characterize the temporal performance of liquid-crystal displays

A method to measure the dynamic modulation transfer function (DMTF) of a liquid-crystal display (LCD) is proposed to characterize its performance when rendering motion images. The method includes a measurement system to capture the temporal luminance variation of a LCD while using a well-designed input data sequence and a simulation model based on smooth pursuit eye tracking and temporal light integration at the human retina. It predicts the perceived performance of a moving sine wave pattern on a LCD and subsequently calculates the DMTF. With this approach, several technologies to reduce motion blur were evaluated and discussed.     

基于分时积分亚像元融合的地球静止轨道平台消颤振技术

相较于低轨卫星线阵扫描成像模式,地球静止轨道面阵成像的曝光时间相对更长,更容易受到平台颤振的影响而造成图像模糊.为了消除由平台颤振引起的像质退化,本文提出了基于分时积分亚像元融合的方法.由于地球静止轨道的凝视成像特性,相机观察区域在长时间内保持不变,因此分时短曝光可以获得多帧目标内容相同,但模糊尺度更低的短曝光图像.然后对多帧短曝光图像采用基于能量区域质心法的相位相关算法进行亚像元图像配准,计算相对偏移量并进行补偿,位移探测准确度可达0.1像元以内,满足卫星平台应用需求.再按亚像元偏移量对多帧图像进行融合,融合的过程可以提升由于曝光时间缩短而降低的单帧图像信噪比,最终可以获得图像清晰度更高、信噪比与原长曝光图像相当、信息辨识度更好的遥感图像.     

Distance rendering and perception of nearby virtual sound sources with a near-field filter model

Headphone rendering of nearby virtual sound sources represents to date an open issue in 3-D audio, due to a number of technical challenges and temporal requirements involved in the measurement of individual Head-Related Transfer Functions (HRTFs). In order to tackle this problem, we propose a filter model of near-field effects based on the Distance Variation Function (Kan et al., 2009). Thanks to its simple structure and low order, the model can be applied to any far-field virtual auditory display to yield a realistic and computationally efficient near-field compensation of spectral and binaural effects. The model is subjectively evaluated in two psychophysical experiments where the relative distance of pairs of virtually rendered sound sources is judged. Results show that even though sound intensity overshadows subtler near-field effects when it is available as a cue for distance, the model is capable of offering relative distance information of near lateral virtual sources when intensity cues are removed. Furthermore, performances of the model in relative distance rendering are compared to those of alternative near-field rendering methods available in the literature.     

基于分时积分亚像元融合的地球静止轨道平台消颤振技术

相较于低轨卫星线阵扫描成像模式,地球静止轨道面阵成像的曝光时间相对更长,更容易受到平台颤振的影响而造成图像模糊.为了消除由平台颤振引起的像质退化,本文提出了基于分时积分亚像元融合的方法.由于地球静止轨道的凝视成像特性,相机观察区域在长时间内保持不变,因此分时短曝光可以获得多帧目标内容相同,但模糊尺度更低的短曝光图像.然后对多帧短曝光图像采用基于能量区域质心法的相位相关算法进行亚像元图像配准,计算相对偏移量并进行补偿,位移探测准确度可达0.1像元以内,满足卫星平台应用需求.再按亚像元偏移量对多帧图像进行融合,融合的过程可以提升由于曝光时间缩短而降低的单帧图像信噪比,最终可以获得图像清晰度更高、信噪比与原长曝光图像相当、信息辨识度更好的遥感图像.     

运动与离焦模糊图像的复原

在运动和离焦所引起的图像模糊的情况中,本文提出了一种新的基于霍夫变换区分离焦模糊和运动模糊两类模糊的方法.该方法通过比较霍夫变换矩阵中的亮点数来区分两类模糊,不仅正确率达到100%,而且抗干扰性能好;其次通过对运动模糊图像做两次方向微分,估计其模糊方向,提高了模糊方向的估计准确度;最后利用改进的Prewiit算子和费米函数计算模糊图像的刃边函数,进而得到图像的调制传递函数,再利用维纳滤波复原图像.实验结果表明:本文算法不仅具有有效性和强抗噪音能力,而且对图像的信噪比要求可以低到20 dB;与传统算法相比,提高了图像的复原质量.     

Restoration of images degraded by extreme mechanical vibrations

A method of numerically calculating the optical transfer function appropriate to any type of image motion and vibration, including random, has been recently developed. This method has been verified experimentally with real vibrations, and the close agreement justifies implementation in image restoration from blur deriving from any type of image motion, including random displacement. Here, image restorations of actual physically degraded images are presented, based on a constrained least squares improvement of the original Wiener filter. Even for extreme vibrations where the blur extent is much larger than the blurred detail, restoration is quite complete. The key to restoration is the determination of the optical transfer function unique to the particular image motion and vibration causing the blur. Results are also presented for low vibration frequency motion of random blur extent, as well as for high vibration frequencies.     

沉浸式虚拟训练中的虚拟手操控技术研究

将人手的自然动作加入沉浸式虚拟现实系统中,可有效提高系统的沉浸感和交互性,简便快捷、成本低廉的虚拟手建模及操控技术,有助于此项内容的推广应用;在对虚拟手骨骼结构模型分析的基础上,提出了基于Leap Motion的虚拟手控制方法和流程;以维修训练为任务背景,设计了四种用于虚拟手操作的手势规则,并对实现流程和关键技术进行了分析;构建基于Unity3D引擎的原型系统对虚拟手进行仿真验证,结果表明,基于Leap Motion的虚拟手操控简单、交互自然,可以满足虚拟现实系统交互需要。     

基于单目视觉的虚拟鼠标方法

自然的交互方式有利于提高增强现实系统的真实感和沉浸感,是增强现实技术的重要研究内容。针对这一问题,提出一种基于单目视觉的虚拟鼠标实现方法,只需要使用单个摄像头,即可对裸手手势进行识别进而模拟真实鼠标动作,最后基于该方法开发了基于单目视觉的虚拟鼠标系统。首先,根据色度信息,分割手部肤色区域;然后,基于指尖的形态学特征识别指尖点,并过滤以排除误检点;最后根据指尖点及其坐标控制光标模拟鼠标动作。实验结果表明,该系统设备简单、精度较高,完全可以实现各种鼠标动作的模拟。     

A novel modified cepstral based technique for blind estimation of motion blur

In the problem of blind image deconvolution, estimation of blurring kernel is the first and foremost important step. Quality of restored image highly depends upon the accuracy of this estimation. In this paper we propose a modified cepstrum domain approach combined with bit-plane slicing method to estimate uniform motion blur parameters, which improves the accuracy without any manual intervention. A single motion blurred image under spatial invariance condition is considered. It is noted that the fourth bit plane of the modified cepstrum carries an important cue for estimating the blur direction. With the exploration of this bit plane no other post processing is required to estimate blur direction. The experimental evaluation is carried out on both real-blurred photographs and synthetically blurred standard test images such as Berkeley segmentation dataset and USC-SIPI texture image database. The experimental results show that the proposed method is capable of estimating blur parameters more accurately than the existing methods.     

Review of a direct epitaxial approach to achieving micro-LEDs

There is a significantly increasing demand of developing augmented reality and virtual reality (AR and VR) devices, where micro-LEDs (μLEDs) with a dimension of ≤ 5 μ m are the key elements. Typically, μLEDs are fabricated by dry-etching technologies, unavoidably leading to a severe degradation in optical performance as a result of dry-etching induced damages. This becomes a particularly severe issue when the dimension of LEDs is ≤ 10 μ m. In order to address the fundamental challenge, the Sheffield team has proposed and then developed a direct epitaxial approach to achieving μLEDs, where the dry-etching technologies for the formation of μLED mesas are not needed anymore. This paper provides a review on this technology and then demonstrates a number of monolithically integrated devices on a single chip using this technology.     

基于Unity 3D的船舶压缩空气系统的虚拟设计

针对目前船舶空气压缩仿真训练系统大多采用半物理仿真与二维软件界面仿真相结合方式训练效果不佳的问题,将虚拟现实技术引入到船舶压缩空气系统的仿真设计;设计一套基于Unity 3D的船舶压缩空气系统,实现虚拟仿真程序和三维虚拟场景的实时交互,生成一个逼真的三维视觉、听觉、触觉的感官世界,加强培训人员的沉浸感,从而获得一种置身于真实环境中的感受;系统可供学员无限制反复训练,节省系统的维护费用,规避实物操作设备中可能出现的各种风险,提高训练效果。     

基于Simulink和VR技术的三维空间电子运动研究

以电子示波器中电子的运动模型为例,探讨了结合Simulink软件和虚拟现实编程语言在虚拟物理实验中应用问题。通过虚拟现实编程语言创建电子运动环境的三维模型,利用Simulink构建了较为完善的、严格遵循客观物理定律并且不以人的主观意识改变的仿真系统。给出了电子在三维空间运动的动画,和不同频率比的李萨如图形。体现出Simulink虚拟现实工具箱仿真物理实验的便捷性、可靠性和科学性。     

基于相位相关的匀速直线运动模糊图像位移参数估计

为估算匀速直线运动模糊图像的运动参数,提出了一种基于相位相关分析的图像配准方法。该方法利用傅里叶变换的平移特性,对产生平移的目标图像进行傅里叶变换并计算归一化互功率谱,其傅里叶逆变换对应二维脉冲函数,通过计算脉冲函数峰值坐标获取位移图像之间的亚像元级位移量。结合相位相关配准原理和线性空间不变退化模型,给出了匀速直线运动点扩散函数及其光学传递函数的数学描述;讨论了匀速直线运动模糊对相位相关配准结果的影响,证明了图像经过匀速直线运动退化后,位移图像之间归一化互功率谱具有不变性。实验结果表明：动态运动模糊图像最大检测误差为0.489 pixel,标准差为0.16 pixel。