视觉触控系统中的行图像获取和照明模块设计

为实现低成本视觉触控系统行图像数据的实时接收和检测,设计了一种基于Cortex-M3处理器的行图像接收单元。针对视觉触控系统在抵抗太阳光干扰方面的局限性,设计了基于全自动曝光方式的红外照明模块。经实际应用,视觉触控系统中可稳定接收反射光带的行图像,且系统能够在约2800Lux的室内有阳光入射的环境中正常使用。

基于自适应阈值的网格图像行分割算法

针对网格图像文字自动识别受网格横线影响的问题,提出将网格图像按照网格横线进行行分割的自适应阈值算法。在对网格图像行分割过程中,首先对灰度图像使用类别方差自动门限法(OSTU算法)取得图像二值化的阈值,将此阈值作为全局阈值对图像进行二值化操作。然后针对图像的二值化数据进行了水平投影,利用统计法取得行分隔的阈值,并结合行分隔阈值实现了网格图像行分割的算法。最后将算法在Matlab中进行了验证和分析。

一种改进的图像匹配算法

基于特征点的匹配是图像匹配的关键方法。提出一种可以实现大量特征点匹配的算法。该算法实现了图像行校正,改进了Harris角点检测算法,提出了一种新的角点指示器,它可以检测出足够多的特征点进行特征点匹配;然后使用sift特征描述运算符描述每个特征点;最后,使用最近邻居距离比算法完成特征点匹配。实验结果表明,提出的算法可以实现大量特征点匹配,对图像匹配算法具有一定的参考意义。

采用ALR算法对Landsat-7图像缺行修复的应用研究

美国陆地卫星Landsat-7上搭载的专题扫描仪（ETM＋）上的扫描行校正器（SLC，scan line corrector）在2003年5月31日发生故障，导致Landsat-7影像出现坏行，难以正常使用。为了使剩余的78％的数据能够被利用，美国航空航天局（NASA）组织专家研究解决这一问题的方案，我们与NASA密切配合，探索了5种修复方法。经过对这5种方法的尝试与试验，其中自适应局部回归（ALR）算法修复后的图像完整没有明显的修复边界，达到理想的效果。本文介绍了ALR算法的基本原理、流程，并将该算法分别应用在美国和北京的缺行图像修复中，取得良好的效果。

Evaluation of fatigue property of asphalt mixtures based on digital image correlation method

In order to evaluate the accumulative of tensile strain in the process of fatigue failure, the digital image correlation（DIC） method was utilized to characterize the tensile strain development of asphalt mixtures in the indirect tensile（IDT）fatigue test. Three typical hot mix asphalt（HMA） mixtures with varying nominal maximum aggregate sizes were tested at four stress levels. During the tests, a digital camera was mounted to capture the displacement/strain fields on the surface of the specimen by recording the real-time change of speckle position. The results indicate that the vertical deformation curve can barely evaluate the fatigue performance accurately due to the non-negligible local deflection near the loading point. However, based on the analysis of strain fields,the optimal fatigue cracking zone is determined as a 40mm×40mm rectangle in the middle of the specimens. Also, a reasonable fatigue model based on the tensile strain curves calculated by DIC is proposed to predict the fatigue lives of asphalt mixtures.

Parallel Image Processing Technology of Surface Detection System

To improve image processing speed and detection precision of a surface detection system on a strip surface,based on the analysis of the characteristics of image data and image processing in detection system on the strip surface,the design of parallel image processing system and the methods of algorithm implementation have been studied. By using field programmable gate array(FPGA) as hardware platform of implementation and considering the characteristic of detection system on the strip surface,a parallel image processing system implemented by using multi IP kernel is designed. According to different computing tasks and the load balancing capability of parallel processing system,the system could set different calculating numbers of nodes to meet the system's demand and save the hardware cost.

Application of TMS320C80 in Image Processing

To study the application of TMS320C80 in image processing, an image processing system was designed based on this device, and the task of real time image processing was well accomplished on the hardware platform. TMS320C80 architecture's high degree of on chip integration and software flexibility will make it widely used in image processing that requires high processing speeds.

Unsaturated expansive soil fissure characteristics combined with engineering behaviors

The relationship among the surface fissure ratio, moisture content, seepage coefficient and deformation modulus of field unsaturated expansive soil in Nanning, Guangxi Province, China, was obtained by a direct or indirect method. Digital images of expansive soil of the surface fissure with different moisture contents were analyzed with the binarization statistic method. In addition, the fissure fractal dimension was computed with a self-compiled program. Combined with in situ seepage and loading plate tests, the relationship among the surface fissure ratio, moisture content, seepage coefficient and deformation modulus was initially established. The surface fissure ratio and moisture content show a linear relation, ＂y=-0.019 1x＋1.028 5＂ for rufous expansive soil and ＂y=-0.07 1x＋2.610 5＂ for grey expansive soil. Soil initial seepage coefficient and surface fissure ratio show a power function relation, ＂y=1× 10^-9exp（15.472x）＂ for rufous expansive soil and ＂y=5× 10^-7exp（4.209 6x）＂ for grey expansive soil. Grey expansive soil deformation modulus and surface fissure ratio show a power fimction relation of ＂y=3.935 7exp（0.993 6x）＂. Based on the binarization and fractal dimension methods, the results show that the surface fissure statistics can depict the fissure distribution in the view of two dimensions. And the evolvement behaviors of permeability and the deformation modulus can indirectly describe the developing state of the fissure. The analysis reflects that the engineering behaviors of unsaturated expansive soil are objectively influenced by fissure.

Acquisition of Directional Parameters in Aerial Images Based on DEM Data

This paper develops a method which can be used to assist aerial navigation by determining the spatial position and posture of the aerial photographic plane. After the method, aerial images match known DEM to capture the spatial position and posture. Some aerial images and terrain data are used to testify our method. Compared with those of analytic and stereo mappers, the results by our method are correspondent to real measurements well.

Automatic Liver Segmentation Scheme for MRI Images Based on Cellular Neural Networks

Currently, the processing speed of exist-ing autormtic liver segmentation for Magnetic Res-onance Imaging （MRI） images is rehtively slow. An automatic liver segmentation scheme for MRI irmges based on Cellular Neural Networks （CNN） is presented in this paper. It ensures the validity of this scheme and at the same time completes the im-age segmentation faster to accurately calculate the liver volume by using parallel computing in real time. In order to facilitate the CNN irmge process-hag, firstly, three-dimensional liver MRI images should be transformed into binary images; second- ly, an appropriate template parameter of the Global Connectivity Detection CNN （GCD CNN） shall be selected to probe the connectivity of the liver to extract the entire liver; and then the Hole-Filler CNN （HF CNN） are used to repair the entire extracting liver and improve the accuracy of fiver segmentation; final-ly, the liver volume is obtained. Results show that the scheme can ensure the accuracy of the automatic seg-mentation of the liver, and it can also improve the processing speed at the same time. The liver volume calculated is in line with the clinical diagnosis.

Using Graphics Processing Units to Parallelize the FDK Algorithm for Tomographic Image Reconstruction

The paper presents the implementation of a parallel version of FDK （Felkamp, David e Kress） algorithm using graphics processing units. Discussion was briefly some elements the computed tomographic scan and FDK algorithm; and some ideas about GPUs （Graphics Processing Units） and its use in general purpose computing were presented. The paper shows a computational implementation of FDK algorithm and the process of parallelization of this implementation. Compare the parallel version of the algorithm with the sequential version, used speedup as a performance metric. To evaluate the performance of parallel version, two GPUs, GeForce 9400GT （16 cores） a low capacity GPU and Quadro 2000 （192 cores） a medium capacity GPU was reached speedup of 3.37.

A Stoppable Clock Based Four Step Search Block-Matching Motion Estimation Architecture

Motion Estimation （ME） is considerate one of the most important compression methods. However, ME involves high computational complexity. The main goal is to reduce power conception and the execution time without reducing image quality. In this paper, the authors have proposed high parallel processing architecture is presented for four-step search block-matching motion estimation. The proposed method is based on the stoppable clock models. The architecture has been simulated and synthesized with VHDL and ASIC （CMOS 45 nm）. Synthesize results show that the proposed architecture reduces the power consumption and achieves a high performance for real time motion estimation.

Underwater Terrain-Aided Navigation Based on Multibeam Bathymetric Sonar Images

Underwater terrain-aided navigation is used to complement the traditional inertial navigation employed by autonomous underwater vehicles during lengthy missions. It can provide fixed estimations by matching real-time depth data with a digital terrain map, This study presents the concept of using image processing techniques in the underwater terrain matching process. A traditional gray-scale histogram of an image is enriched by incorporation with spatial information in pixels. Edge comer pixels are then defined and used to construct an edge comer histogram, which employs as a template to scan the digital terrain map and estimate the fixes of the vehicle by searching the correlation peak. Simulations are performed to investigate the robustness of the proposed method, particularly in relation to its sensitivity to background noise, the scale of real-time images, and the travel direction of the vehicle. At an image resolution of 1 m2/pixel, the accuracy of localization is more than 10 meters.

Surgical simulation and evaluation in anterior cruciate ligament reconstruction with image-free navigation

A surgical simulation and evaluation method in the anterior cruciate ligament(ACL)reconstructionwith image-free navigation was presented.Firstly,video tracking module,bone surface reconstructionmodule and virtual simulation module of this system were discussed.Secondly,the coordinate relations ofseveral surgery objects(including surgical instrument,anatomical,camera and screen)in the surgicalenvironment,the tracking based on MicronTracker with two cameras and the bone surface real-time recon-struction based on the Delaunay algorithm were introduced in detail.Finally,experiments of anisometrymeasurement and virtual simulation on two plastics were carried out to verify the validity of the proposedmethod.The anisometry value of reconstructed ACL was 8.970039mm.The effectiveness of ACL recon-struction has been proved by preliminary evaluation trials.

Fast distributed and parallel pre-processing on massive satellite data using grid computing

Distributed/parallel-processing system like sun grid engine(SGE) that utilizes multiple nodes/cores is proposed for the faster processing of large sized satellite image data. After verification, distributed process environment for pre-processing performance can be improved by up to 560.65% from single processing system. Through this, analysis performance in various fields can be improved, and moreover, near-real time service can be achieved in near future.

视觉幻真在文艺复兴宗教图像中的功能

在艺术史和艺术理论的研究中,人们多从真实再现和视觉心理的角度讨论图像中的幻真问题。然而,在西方漫长的幻真实践中,幻真的价值或功能实现是一个多元因素决定的文化过程,尤其在文艺复兴时代的宗教绘画中,幻真实践是与图像的观看场域以及观者在这个场域的神圣的凝视联系在一起的,其图像冲动的本质既非单纯的真实再现,也不是为了所谓的视幻觉,而是图像对神圣空间的重置。

Experiment and analysis on microscopic characteristics of pedestrian movement in building bottleneck

In this paper, evacuation experiments are carried out to study pedestrian movement behaviors in building bottleneck. An image processing method based on mean-shift algorithm is used to extract pedestrian movement trajectory. Based on the extracted trajectory, we analyze the microscopic movement characteristics of pedestrians such as lane formation, change of velocity and distance between two sequential pedestrians. A pedestrian lane is a group of pedestrians moving in a column. The lane formation is verified by the pedestrian trajectory and distribution of pedestrian’s lateral positions (x direction in the paper): lane number changes from one to two, three or even more with the increasing bottleneck width when pedestrians pass through the bottleneck. By analyzing the pedestrian movement behaviors in the same pedestrian lane, we find three typical movement modes in the bottleneck: time-lag acceleration, synchronous acceleration, and avoiding deceleration. Through analyzing the time intervals when successive pedestrians pass through the bottleneck, we find that most pedestrians adjust their velocities according to the distance to the forward pedestrians. Results also indicate that due to different cultures, pedestrians flux in China and Germany may have some differences besides their similarities.

Spinal cord injury in Parkour sport （free runn,ng）： a rare case report

A 24-year-old male was transferred to the emergency department while being in the state of quadriplegia with a history of performing Parkour sport, which is also called double front flip. Neurological examination revealed that the patient＇s muscle power was 0/5 at all extremities. The patient did not show any sense of light touch or pain in his extremities. In radiological studies, cervical spine X-ray and CT scan images showed C4-C5 subluxation with bilateral locked facets and spinal cord injury. The results of this very rare case study revealed that exercising Parkour sport without taking into account safety standards could result in irreversible injuries to the cervical spinal cord with fatal outcome.

PIV measurements of turbulent jets issuing from triangular and circular orifice plates

The present study experimentally investigated the near-field flow mixing characteristics of two turbulent jets issuing from equilateral triangular and circular orifice plates into effectively unbounded surroundings,respectively.Planar particle image velocimetry(PIV) was applied to measure the velocity field at the same Reynolds number of Re=50,000,where Re = UeDe /with Ue being the exit bulk velocity and the kinematic viscosity of fluid,D e the equivalent diameters.The instantaneous velocity,mean velocity,Reynolds stresses were obtained.From the mean velocity field,the centreline velocity decay rate and half-velocity width were derived.Comparing the mixing characteristics of the two jets,it is found that the triangular jet has a faster mixing rate than the circular counterpart.The triangular jet entrainments with the ambient fluid at a higher rate in the near field.This is evidenced by a shorter unmixed core,faster Reynolds stress and centreline turbulence intensity growth.The primary coherent structures in the near field are found to break down more rapidly in the triangular jet as compared to the circular jet.Over the entire measurement region,the triangular jet maintained a higher rate of decay and spread.Moreover,all components of Reynolds stress of the triangular jet appear to reach their peaks earlier,and then decay more rapidly than those of the circular jet.In addition,the axis-switching phenomenon is observed in the triangular jet.

Experimental investigation on the wing-wake interaction at the mid stroke in hovering flight of dragonfly

This paper focuses on flow structures of the wing-wake interaction between the hind wing and the wake of the forewing in hovering flight of a dragonfly since there are arguments whether the wing-wake interaction is useful or not.A mechanical flapping model with two tandem wings is used to study the interaction.In the device,two identical simplified model wings are mounted to the flapping model and they are both scaled up to keep the Reynolds number similar to those of dragonfly in hovering flight since our experiment is conducted in a water tank.The kinetic pattern of dragonfly(Aeschna juncea) is chosen because of its special interesting asymmetry.A multi-slice phase-locked stereo particle image velocimetry(PIV) system is used to record flow structures around the hind wing at the mid downstroke(t/T=0.25) and the mid upstroke(t/T=0.75).To make comparison of the flow field between with and without the influence of the wake,flow structures around a single flapping wing(hind wing without the existence of the forewing) at these two stroke phases are also recorded.A local vortex identification scheme called swirling strength is applied to determine the vortices around the wing and they are visualized with the iso-surface of swirling strength.This paper also presents contour lines of z at each spanwise position of the hind wing,the vortex core position of the leading edge vortex(LEV) of hind wing with respect to the upper surface of hind wing,the circulation of the hind wing LEV at each spanwise position and so on.Experimental results show that dimension and strength of the hind wing LEV are impaired at the mid stroke in comparison with the single wing LEV because of the downwash from the forewing.Our results also reveal that a wake vortex from the forewing traverses the upper surface of the hind wing at the mid downstroke and its distance to the upper surface is about 40% of the wing chord length.At the instant,the distance of the hind wing LEV to the upper surface is about 20% of the wing chord length.Thus,there must be a wing-wake interaction mechanism that makes the wake vortex become an additional LEV of the hind wing and it can partly compensate the hind wing for its lift loss caused by the downwash from the forewing.