基于高速摄影图像的轻气炮弹速测量研究

目前对轻气炮弹丸测量的方法通常采用磁测速、激光遮断测速两种方法,这两种方法受到弹丸材质、尺寸、弹前激波等影响时易导致测量结果失效;针对此类问题,提出了一种可靠性更高的基于高速摄影图像模板匹配的轻气炮弹丸速度测量方法;利用高速摄影相机、辅助光源、刻度标尺等组成高速弹丸摄影系统,设置高速弹丸拍摄方案,得到轻气炮弹丸在观察室运动过程的高速摄影结果;采用弹丸目标模板匹配的方法对摄影结果进行计算,得到弹丸运动过程中的位置信息从而得到弹丸速度;将计算结果与激光遮断测速方法得到的速度值进行了对比,满足试验要求,证明了该方法既能可独立作为轻气炮发射弹丸测速手段,也可为现有测试手段提供有效校核.     

纳米级光栅容栅融合测量系统研究

利用容栅测量系统中激励信号源的设计技术,产生一组多相输出的调制信号源,作为光栅测量系统的多相线阵光源激励信号,发出的多相调制光信号,再经过标尺光栅调制后,由光电转换元件接收并获得一个复合的电信号.该信号经处理电路后,可获得一个频率与激励信号源的基波频率相等的电信号,检测这两个信号间的相位差的变化,可得到标尺光栅的移动距离x.将容栅和光栅测量技术有机地结合,并通过提高相位检测电路的细分数和减小线阵光源的点距,可达到亚微米或纳米级的测量分辨力.     

基于误差校正的高精度三维测量系统

基于投影仪的结构光三维测量系统已得到了广泛的应用,但由于投影仪与相机的非线性特点,使用现有相位恢复算法得到的相位值具有一定的误差,影响了三维测量的精度。提出了一种基于二次型误差校正的高精度相位恢复算法。通过对标准平板进行相位恢复,分析其误差分布特征;用二次多项式对该误差进行逼近,得到误差的分布规律;根据求出的二次型误差模型对投影仪结构光系统得到的初始相位值进行修正,得到了高精度的相位恢复结果。实验表明,该算法比现有算法具有更高的相位恢复和三维测量精度。     

铝合金焊接熔池图象传感器

采用图象处理与模式识别的方法对铝合金的焊接质量进行智能控制还没有成功 ,因为铝合金表面不同于其它黑色金属 ,铝合金表面反射全波段的可见光 ,熔池与周围金属的灰度对比度极弱 ,在焊接电流较大时弧光强烈 ,弧光以及熔池周围金属的反射光足以掩盖熔池 ,普通的光学传感器无法在上述苛刻条件下取得铝合金焊接熔池区域的图象。通过光谱分析 ,可以设计全新的光学传感器 ,利用普通工业CCD摄像机获得清晰的铝合金焊接熔池区域图象 ,为铝合金智能化焊接打下了良好的基础     

基于构造简化模型和局部大气光遮罩的去雾算法

针对雾天条件下图像降质的问题,提出一种基于构造简化模型和局部大气光遮罩的单幅图像去雾算法.该方法从大气散射模型出发,通过构造雾浓度检测函数,检测出准确的大气光值选取区域,进而建立简化大气散射模型,并利用简化模型构造局部大气光遮罩.然后通过计算拉依达准则下限值的策略获取引导图,利用引导滤波进行区域平滑并保持边缘特性,再结...     

Quantifying light-fishing for Dosidicus gigas in the eastern Pacific using satellite remote sensing

The distribution and abundance of the fleet targeting Jumbo flying squid (Dosidicus gigas) in the Eastern Pacific is examined during the 1999 fishery season. The commercial fishery consists of a multinational jigging fleet, which fish at night using powerful lights to attract squid. The emission of light from these vessels can be observed using satellite-derived imagery obtained by the United States Defence Meteorological Satellite Program-Operational Linescan System (DMSP-OLS). In order to quantify fishing effort using lights, data on the distribution and abundance of vessels were obtained via satellite tracking using the ARGOS system. The distribution of the fishery as derived from light signatures was found to closely resemble that derived from ship location data. By using ARGOS data to calibrate DMSP-OLS images, we are able to estimate fishing effort in terms of the ‘area illuminated’ by the fishing fleet. Light signatures derived from DMSP-OLS were successfully used to quantify fishing effort, estimating the number of vessels fishing to within ±2 in 85 out of 103 satellite images (83%). High seas fishing was also quantified, with light signatures corresponding to a single fishing vessel observed in 11 out of 103 satellite passes during the fishery season (July-December 1999). This study examines how much light (in terms of area) is emitted by a single squid fishing vessel, and may prove to be a valuable tool in assessing and policing fisheries using satellite remote sensing.     

基尼指数成本量指导的抗遮挡光场深度估计方法

光场相机能够实现一次拍摄即获得三维场景的多视角信息,在深度估计领域中具有独特优势.但是,当场景中存在复杂遮挡时,现有深度估计方法提取深度信息的精度会明显降低.针对该问题,设计一种基尼指数成本量指导下的抗遮挡光场深度估计方法.首先,利用光场重聚焦方法获得焦栈图像;然后,构造中心视角与其他视角的基尼指数成本量,并根据成本最小原则计算得到初始深度图;最后,结合彩色图进行联合引导滤波,获得最终的高精度的深度图像.实验结果表明,所提方法对复杂场景更加鲁棒,能够在较小的算法复杂度下获取更好的深度估计结果.相比于其他先进方法,所提方法获取的深度图精度更高,图像边缘保留效果更好,在HCI数据集上的MSE₁₀₀指标平均降低约7.8%.     

Adaptive Sampling of Area Light Sources in Ray Tracing Including Diffuse Interreflection

Ray tracing algorithms that sample both the light received directly from light sources and the light received indirectly by diffuse reflection from other patches, can accurately render the global illumination in a scene and can display complex scenes with accurate shadowing. A drawback of these algorithms, however, is the high cost for sampling the direct light which is done by shadow ray testing. Although several strategies are available to reduce the number of shadow rays, still a large number of rays will be needed, in particular to sample large area light sources. An adaptive sampling strategy is proposed that reduces the number of shadow rays by using statistical information from the sampling process and by applying information from a radiosity preprocessing. A further reduction in shadow rays is obtained by applying shadow pattern coherence, i.e. reusing the adaptive sampling pattern for neighboring sampling points.     

Visual Enhancement of Underwater Images Using Transmission Estimation and Multi-Scale Fusion

The demand for the exploration of ocean resources is increasing exponentially. Underwater image data plays a significant role in many research areas. Despite this, the visual quality of underwater images is degraded because of two main factors namely, backscattering and attenuation. Therefore, visual enhancement has become an essential process to recover the required data from the images. Many algorithms had been proposed in a decade for improving the quality of images. This paper aims to propose a single image enhancement technique without the use of any external datasets. For that, the degraded images are subjected to two main processes namely, color correction and image fusion. Initially, veiling light and transmission light is estimated to find the color required for correction. Veiling light refers to unwanted light, whereas transmission light refers to the required light for color correction. These estimated outputs are applied in the scene recovery equation. The image obtained from color correction is subjected to a fusion process where the image is categorized into two versions and applied to white balance and contrast enhancement techniques. The resultants are divided into three weight maps namely, luminance, saliency, chromaticity and fused using the Laplacian pyramid. The results obtained are graphically compared with their input data using RGB Histogram plot. Finally, image quality is measured and tabulated using underwater image quality measures.     

白光纹影的流场检测及信息处理

介绍白光纹影流场检测系统的组成,测量原理和计算分析,并以酒精灯火焰和电吹风作为测试段的扰动场得到实验结果。纹影法的原理是用刀口在焦点处去切割光源像,把光线受流场的扰动转变为记录平面上的光强分布,从而对流场进行显示和测量。     

基于Parzen窗法的贝叶斯参数估计

针对贝叶斯估计中所需的非规则概率密度函数, 提出用Parzen窗算法估计相关概率密度, 从而求解不同损失函数下的贝叶斯参数估计器. 实例分析中, 选择一组电阻测量值作为样本, 利用Parzen窗法计算出相应的概率密度函数, 最后用交叉验证法得出了该样本的最小绝对值误差参数估计器.     

Replica Exchange Light Transport

We solve the light transport problem by introducing a novel unbiased Monte Carlo algorithm called replica exchange light transport, inspired by the replica exchange Monte Carlo method in the fields of computational physics and statistical information processing. The replica exchange Monte Carlo method is a sampling technique whose operation resembles simulated annealing in optimization algorithms using a set of sampling distributions. We apply it to the solution of light transport integration by extending the probability density function of an integrand of the integration to a set of distributions. That set of distributions is composed of combinations of the path densities of different path generation types: uniform distributions in the integral domain, explicit and implicit paths in light (particle/photon) tracing, indirect paths in bidirectional path tracing, explicit and implicit paths in path tracing, and implicit caustics paths seen through specular surfaces including the delta function in path tracing. The replica‐exchange light transport algorithm generates a sequence of path samples from each distribution and samples the simultaneous distribution of those distributions as a stationary distribution by using the Markov chain Monte Carlo method. Then the algorithm combines the obtained path samples from each distribution using multiple importance sampling. We compare the images generated with our algorithm to those generated with bidirectional path tracing and Metropolis light transport based on the primary sample space. Our proposing algorithm has better convergence property than bidirectional path tracing and the Metropolis light transport, and it is easy to implement by extending the Metropolis light transport.     

Propagation characteristics of an optically controlled double‐channel lossy‐dielectric waveguide

A double‐channel lossy‐dielectric waveguide, having its propagation characteristics controlled by the action of light, is analyzed here. The light is incident on a semiconductor material that constitutes the inner channel of the waveguide structure, generating a plasma. The analysis of the problem is done by using the finite difference in the frequency domain method which was found to be efficient for this analysis. The results presented here were confirmed with those obtained using the finite element method. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 127–131, 2000.     

A simple device for quantitative colorimetric diffuse reflectance measurements

A very simple and low cost reflectometer, for colorimetric diffuse reflectance measurements is described. The proposed instrument uses a light dependent resistor (LDR), as a sensor, and a light emitter diode (LED), as light source. The performance of the device was compared with that of a commercial instrument, measuring the reflectance of the Pantone^® Process Black Uncoated Palette. The quantitative analysis of nickel, in a catalyst, using dimethylglyoxime as colorimetric reagent, was also used to test the device. The observed precision was about 6% (R.S.D.). These results were compared with those obtained by the gravimetric method using the same reaction, through the statistical Student’s t-test procedure. A complete agreement was observed. The good quality of all the obtained results allows the recommendation of the instrument for diffuse reflectance measurements including quantitative analytical procedures.     

Fuzzy logic based smart traffic light simulator design and hardware implementation

The objective of this study is to develop fuzzy logic based traffic junction light simulator system for design and smart traffic junction light controller purposes and also to observe its performance. Traffic junction simulator hardware is developed to overcome difficulties of working in a real environment and to easily test the performance of the controller. By using the traffic light simulator developed in this study, results of constant duration (conventional) traffic light controller and fuzzy logic based traffic light controller are compared where the vehicle inputs are supplied by the simulator. Statistical experimental results obtained from the implemented simulator show that the fuzzy logic traffic light controller dramatically reduced the waiting time at red lights since the controller adapts itself according to traffic density. It is obvious that the intelligent light controller is going to provide important advantages in terms of economics and environment.     

智能获取装箱管状工件抓取位置的研究

机械手智能抓取工件时,工件抓取位置的获取是基于机器视觉精确装配的重点。针 对环境较复杂的装箱管状工件的装配抓取环节,建立合理的机器视觉系统,利用正向照明系统对 工件表面产生的反光直光条特征,提出了一种Gaussian 拟合与Hough 变换相结合的拟合算法。首 先利用Gaussian 拟合提取各光条法向上的中心坐标,然后将获取的坐标点集运用Hough 变换进行 拟合,最后根据获取的各光条中心线计算各工件的抓取位置。实验结果表明该方法能同时实现多 条光条直线的拟合,又能抑制干扰点或噪声的影响,有效实现装箱工件抓取位置的智能获取。     

枕型PSD动态响应特性研究

建立了S1880枕型位置敏感探测器(PSD)的有限元仿真模型,并对其动态响应特性进行了仿真,得到了3个扫描速度下的动态响应误差曲线,通过分析得出结论:PSD产生的动态响应误差随着扫描速度的增大而增大,在光敏面中心线上沿x轴方向匀速直线扫描时,PSD的动态响应误差最大值之比近似等于相应的光源扫描速度之比。仿真结果对枕型PSD的实际工程应用具有一定实用价值。     

基于三通道融合的结构光中心条纹提取算法

实现坝体连接处永久缝的非接触式三维形变测量方法,对保障大坝安全运行具有重要的意义。结构光用来快速获取待测坝体拼接缝部位的表面形貌数据,并利用所获得数据对待测物体表面相貌的三维重构获得缝隙部位形变状态。由于结构光的光条中心提取精度易受噪声干扰,提出了一种三通道特征融合算法来提取条纹中心点。首先,利用方向梯度直方图、局部二值模式和Gabor函数得到三幅光条特征图像。然后,利用图像融合算法确定最终的特征图像。最后,用细化骨架的方法得到中心线。实验结果证明,相较于Steger算法,该方法的最大和平均列坐标差下降至2像素和0.069像素,且测量误差减小至0.114 mm。     

Evaluating and improving color washout of vertical aligned liquid crystal display

We demonstrated an optimized 8-domain vertical aligned (VA) liquid crystal display (LCD) by minimizing its color washout. The index G is adopted to analyze the degree of color washout through simulation. By using linearly and circularly polarized incident light, the optimized regime of the area and applied voltage ratios of sub-pixels is obtained. In the experiments with the circularly polarized light, the images are sensuously improved in a coupled capacity type LCD by applying the simulated applied voltage ratio of two sub-pixels.     

视觉测量中光平面的标定方法研究

讨论了基于视觉的激光扫描测量中,光平面的直接标定方法。为了进一步提高系统的测量精度,在研究了投影矩阵与坐标变换关系的基础上提出了一种光平面的间接标定法,利用标定靶平面所确定的约束关系,通过投影矩阵求解光条上特征点的世界坐标,再建立超定方程组求解光平面的法向量。该方法提高了光平面的标定精度,进而提高了三维重建的精度。最后通过实例对两种标定方法在三维重建中的精度进行了比较。