目标位姿测量中的三维视觉方法

要测量出一组特征点分别在两个空间坐标系下的坐标 ,就可以求解两个空间目标间的位姿关系 .实现上述目标位姿测量方法的前提条件是要保证该组特征点在不同坐标系下 ,其位置关系相同 ,但计算误差的存在却破坏了这种固定的位置关系 .为此 ,提出了两种基于模型的三维视觉方法——基于模型的单目视觉和基于模型的双目视觉 ,前者从视觉计算的物理意义入手 ,通过简单的约束迭代求解实现模型约束 ;后者则将简单的约束最小二乘法和基于模型的单目视觉方法融合在一起来实现模型约束 .引入模型约束后 ,单目视觉方法可以达到很高的测量精度 .而基于模型的双目视觉较传统的无模型立体视觉方法位移精度提高有限 ,但姿态精度提高很多

Localization and tracking of phonating finless porpoises using towed stereo acoustic data-loggers

Cetaceans produce sound signals frequently. Usually, acoustic localization of cetaceans was made by cable hydrophone arrays and multichannel recording systems. In this study, a simple and relatively inexpensive towed acoustic system consisting of two miniature stereo acoustic data-loggers is described for localization and tracking of finless porpoises in a mobile survey. Among 204 porpoises detected acoustically, 34 individuals (similar to 17%) were localized, and 4 of the 34 localized individuals were tracked. The accuracy of the localization is considered to be fairly high, as the upper bounds of relative distance errors were less than 41% within 173 m. With the location information, source levels of finless porpoise clicks were estimated to range from 180 to 209 dB re 1 mu Pa pp at 1 m with an average of 197 dB (N=34), which is over 20 dB higher than that estimated previously from animals in enclosed waters. For the four tracked porpoises, two-dimensional swimming trajectories relative to the moving survey boat, absolute swimming speed, and absolute heading direction are deduced by assuming the animal movements are straight and at constant speed in the segment between two consecutive locations.

Off-axis sonar beam pattern of free-ranging finless porpoises measured by a stereo pulse event data logger

The off-axis sonar beam patterns of eight free-ranging finless porpoises were measured using attached data logger systems. The transmitted sound pressure level at each beam angle was calculated from the animal's body angle, the water surface echo level, and the swimming depth. The beam pattern of the off-axis signals between 45 and 115 (where 0 corresponds to the on-axis direction) was nearly constant. The sound pressure level of the off-axis signals reached 162 dB re 1 mPa peak-to-peak. The surface echo level received at the animal was over 140 dB, much higher than the auditory threshold level of small odontocetes. Finless porpoises are estimated to be able to receive the surface echoes of off-axis signals even at 50-m depth. Shallow water systems (less than 50-m depth) are the dominant habitat of both oceanic and freshwater populations of this species. Surface echoes may provide porpoises not only with diving depth information but also with information about surface direction and location of obstacles (including prey items) outside the on-axis sector of the sonar beam. 2005 Acoustical Society of America.

一种立体视觉系统高精度标定方法

本文介绍使用广角镜头成像的立体视觉系统的高精度标定方法,该方法利用平面单应矩阵约束估计像机内外参数的初值,优化过程中将三维重投影误差作为评价函数,结合遗传算法完成寻优过程,以保证估计出的像机参数是全局最优,避免陷入局部极小。实验结果表明:该方法的空间定位精度与传统方法相比有很大程度的提高。

The Effects of Visual Object Size in The Depth Perception in KM Mouse

Whether mice perceive the depth of space dependent on the visual size of object targets was explored when visual cues such as perspective and partial occlusion in space were excluded. A mouse was placed on a platform the height of which is adjustable. The platform located inside a box in which all other walls were dark exception its bottom through that light was projected as a sole visual cue. The visual object cue was composed of 4x4 grids to allow a mouse estimating the distance of the platform relative to the grids. Three sizes of grids reduced in a proportion of 2/3 and seven distances with an equal interval between the platform and the grids at the bottom were applied in the experiments. The duration of a mouse staying on the platform at each height was recorded when the different sizes of the grids were presented randomly to test whether the Judgment of the mouse for the depth of the platform from the bottom was affected by the size information of the visual target. The results from all conditions of three object sizes show that time of mice staying on the platform became longer with the increase in height. In distance of 20 similar to 30 cm, the mice did not use the size information of a target to judge the depth, while mainly used the information of binocular disparity. In distance less than 20 cm or more than 30 cm, however, especially in much higher distance 50 cm, 60 cm and 70 cm, the mice were able to use the size information to do so in order to compensate the lack of binocular disparity information from both eyes. Because the mice have only 1/3 of the visual field that is binocular. This behavioral paradigm established in the current study is a useful model and can be applied to the experiments using transgenic mouse as an animal model to investigate the relationships between behaviors and gene functions.

Comparison of stationary acoustic monitoring and visual observation of finless porpoises

The detection performance regarding stationary acoustic monitoring of Yangtze finless porpoises Neophocaena phocaenoides asiaeorientalis was compared to visual observations. Three stereo acoustic data loggers (A-tag) were placed at different locations near the confluence of Poyang Lake and the Yangtze River, China. The presence and number of porpoises were determined acoustically and visually during each 1-min time bin. On average, porpoises were acoustically detected 81.7 +/- 9.7% of the entire effective observation time, while the presence of animals was confirmed visually 12.7 +/- 11.0% of the entire time. Acoustic monitoring indicated areas of high and low porpoise densities that were consistent with visual observations. The direction of porpoise movement was monitored using stereo beams, which agreed with visual observations at all monitoring locations. Acoustic and visual methods could determine group sizes up to five and ten individuals, respectively. While the acoustic monitoring method had the advantage of high detection probability, it tended to underestimate group size due to the limited resolution of sound source bearing angles. The stationary acoustic monitoring method proved to be a practical and useful alternative to visual observations, especially in areas of low porpoise density for long-term monitoring.

Estimation of the detection probability for Yangtze finless porpoises (Neophocaena phocaenoides asiaeorientalis) with a passive acoustic method

Yangtze finless porpoises were surveyed by using simultaneous visual and acoustical methods from 6 November to 13 December 2006. Two research vessels towed stereo acoustic data loggers, which were used to store the intensity and sound source direction of the high frequency sonar signals produced by finless porpoises at detection ranges up to 300 m on each side of the vessel. Simple stereo beam forming allowed the separation of distinct biosonar sound source, which enabled us to count the number of vocalizing porpoises. Acoustically, 204 porpoises were detected from one vessel and 199 from the other vessel in the same section of the Yangtze River. Visually, 163 and 162 porpoises were detected from two vessels within 300 m of the vessel track. The calculated detection probability using acoustic method was approximately twice that for visual detection for each vessel. The difference in detection probabilities between the two methods was caused by the large number of single individuals that were missed by visual observers. However, the sizes of large groups were underestimated by using the acoustic methods. Acoustic and visual observations complemented each other in the accurate detection of porpoises. The use of simple, relatively inexpensive acoustic monitoring systems should enhance population surveys of free-ranging, echolocating odontocetes. (C) 2008 Acoustical Society of America.

TEM study of dislocations in ZnTe/GaAs heterostructure grown by hot-wall epitaxy

A ZnTe layer grown on GaAs substrate by hot-wall epitaxy (HWE) was studied using transmission electron microscopy (TEM). For a (110) cross-sectional specimen, its (001) ZnTe/GaAs interface was analysed by large angle stereo-projection (LASP) and high resolution electron microscopy (HREM). In the LASP, a double diffraction occurred and moire fringes were formed, meanwhile misfit dislocations were revealled clearly by weak beam technique. In HREM, not only Lomer and 60 degrees types of misfit dislocations were observed, but also two types of stacking faults were analysed. The residual strain was estimated by both methods.

2-C-支链-1,6-脱水吡喃葡萄糖的开环反应及吡喃烯糖的合成研究

在糖化学合成中，1,6-脱水吡喃糖不仅是合成具有生物活性低聚糖、糖共体、抗原、抗体以及天然产物等化合物重要原料，而且还是许多具有生物活性的天然产物的结构单元。同时，它还具有[3,2,1]的双环缩醛结构，使其在糖化学合成中具有高的立体选择性和区域选择性，同时减少了C-1 和C-6 位的保护和去保护的优点。此外，环内的缩醛开环后，又可以相应地在C-1 和C-6 位进行官能团转化以及糖苷化反应。 本文报道了一种新的1,6-脱水吡喃糖的合成方法，并设计合成了2-C-支链-1,6-脱水吡喃葡萄糖1-195、1-197、1-198 以及2-C-支链-6-硫代1,6-脱水吡喃葡萄糖1-225。到目前为止，1,6-脱水糖开环并进行糖苷化反应，存在选择性较差、产率低的缺点。我们发现，在乙腈做溶剂的条件下，NiCl5 能高立体选择性高产率地催化化合物1-195、1-197、1-198 开环并与ROH、RSH 发生糖苷化反应。在NiCl5-乙腈条件下，合成了一系列2-C-支链-α-糖苷和2-C-支链-β-硫代糖苷，并对2-C-支链1,6-脱水吡喃葡萄糖的生成机理以及开环机理进行了探讨。 烯糖在糖化学合成中是重要的起始原料，从Fischer 首次合成烯糖至今，一直不断地有新的合成方法出现。但目前文献报道的方法存在所用试剂有毒、价格贵和操作繁琐等缺点。我们对Fischer-Zach 方法进行了改进， 发现Zn-NaH2PO4-H2O 和Zn-PEG600-H2O 体系都能很好地合成烯糖。该方法具有条件温和、绿色环保、操作简单的优点。在Zn-NaH2PO4 溶液或Zn-PEG600 条件下，以溴代糖为原料，高产率地合成一系列的烯糖。 The 1,6-anhydrohexopyranoses are crucial subunits of myriad bioactive nature products, as well as important syntons of carbohydrate chemistry which have been extensively used to prepare the biologically potential oligosaccharides, glycoconjugates, antibiotics, and structurally varied nature products. Their particular [3.2.1] bicyclic skeleton makes them have high regio- and stereo-control in a variety of reactions, and such structure avoids protecting hydroxyl groups at C1 and C6.Additionally, the cleavage of the internal acetal under acidic conditions could be beneficial for further transformations of functional group and glycosylation of the corresponding pyranosyl sugar at the C6 or C1 site. Herein we developed a novel approach to prepare the 1,6-anhydrohexopyranose, and synthesized the 2-C-branched-1,6-anhydrohexopyranose 1-195, 1-197, 1-198 and 2-C-branched-6-thio-1,6-anhydrohexopyranose 1-225. Until now, glycosylation of 1,6-anhydrohexopyranoses has been limited because of the low yields and low stereoselectivity. In this paper, we found that NiCl5-MeCN system could selectively cleave the ring of 1,6-anhydrohexopyranoses with alcohols and thiols at room temperature in high yields. A series of 2-C-branched-α-glycosides and 2-C-branched-β-thioglycosides have been synthesized via NiCl5-catalyzed. Furthermore, we investigated the formation and ring-opening mechanism of 2-C-acetylmethyl-1,6-anhydrohexopyranose. Glycals are significant starting material in carbohydrate chemistry. After the Fischer-Zach method for forming glucal was reported for the first time, the numerous synthetic methods for glycals have been explored. However, there are several drawbacks in the existing methods, such as the usage of very expensive and toxic reagents, intricate operation, and the influence of acid-sensitive and base-sensitive functional group. We improved the Fischer-Zach method and developed a facile, mild and environmentally benign methodology towards the synthesis of the glycals in Zn-NaH2PO4-H2O or Zn-PEG600-H2O system. Our method involves the treatment of glycosyl bromides with Zn in NaH2PO4 aqueous solution or PEG600-H2O at room temperature, affording various glycals in excellent yields.

生物催化的Baeyer-Villiger氧化反应研究

Baeyer-Villiger氧化反应是一种很重要的化学反应，产生的许多中间体或产物可以被用来生产多种化学产品和药物。此反应具有多功能性，可以氧化多种羰基化合物，但是化学方法中的必需反应物——氧化剂在生产、储存、运输、反应的过程中都存在很多的不安全因素，反应的立体选择性也不强，而生物转化则具有底物选择性、立构选择性、化学选择性、对映选择性等一般化学反应中不具备的优点，在精细化工中占有很大的优势。在工业生物催化中有很好的应用前景。 为了研究生物催化的Baeyer-Villiger反应，我们从本实验室保藏菌种中分离筛选出一株能够以环己酮作为唯一碳源的菌株，进行初步研究并对其产物进行GC/MS定性，探讨了pH，装液量，底物浓度，培养时间，温度以及转速等条件对细菌生长的影响，并进一步研究了细菌的底物广谱性。 此菌株经鉴定属于邻单胞菌属Plesiomonas sp.)， 根据正交试验，确定了菌的最佳生长条件：底物浓度为1mL/L，底物浓度过高对菌株生长有抑制作用，转速为150 rpm ，温度为30℃ ，pH为7.0； 此菌株转化环己酮的产物通过GC/MS检测含有内酯，表明此菌株能够催化Baeyer-Villiger氧化反应；此菌株还能够以与环己酮有相似结构的环己烷，环戊酮等作为唯一碳源生长，说明此菌株底物利用范围比较广，用途比较广泛。 Baeyer-Villiger oxidation is an important chemical conversion, its products and intermediates can be used to produce a lot of medicine and fine chemicals. Its success is largely due to its versatility: a variety of carbonyl compounds can be oxidized, a large number of functional groups are tolerated, the regiochemistry is highly predictable and so on, but the oxidants that the traditional chemistry way needs have a number of problem in their production, storage, transportation and reaction, Chemistry way has not a high stereochemistry yet. However, biotransformations have many attractive characters, such as substrate-, stereo-, chemo- and enantioselectivity, so it has a great advantage in the fine chemical industry and has a bright prospect in the industrial biological catalysis. In order to study Baeyer-Villiger oxidation, we isolated a strain which can utilize cyclohexanone as sole carbon source and had a primary research on it. Its product was identified by GC/MS. Effects of pH, volume, concentration of cyclohexanone, cultivating time, temperature and rotate speed on the growth of bacteria were discussed, and the other organic substrates were also studied. The strain was identified as Plesiomonas sp.. The result of orthogonal test made it sure that the best growth condition of the strain is: rotate speed 150 rpm, temperature 30℃, pH7.0, concentration of cyclohexanone1ml/L. There is caprolactone in the product of the fermentation with cyclohexanone as substrate by GC/MS,which indicated that the strain can catalyse Baeyer-Villiger oxidation.In addition,the strain can utilize other organic substrates having the similar structure with cyclohexanone such as cyclohexane, cyclopentanone, Swertiamarin as sole carbon source.So the strain can be applied extentively.

单相机全向立体视觉研究

折反射全向成像系统是由普通透视相机和反射镜面组成的全向成像装置，可实时获取360°无需拼接的全景图像，近年来已成为研究热点并在视频会议、三维重建和移动机器人导航等领域有着广泛的应用。 本文主要对单相机全向立体视觉系统的设计、标定、匹配以及三维重建展开研究。介绍了一种可实时获取全向三维信息的折反射全向立体视觉光学装置OSVOD（Omnidirectional Stereo Vision Optical Device），OSVOD由两个双曲面镜和一个普通透视相机组成。其中两个双曲镜面上下同轴、间隔一定距离固定在一个玻璃筒内，下镜面中间开有一孔，上镜面通过下镜面的孔在相机像平面上成像，这样空间一点经上下反射镜的反射在像平面上有两个像点，用一个相机实现了立体视觉。两镜面的共同轴和相机镜头的光轴共线，共同焦点和镜头的光心重合，该配置能保证系统满足单一视点约束SVP（Single View-Point）。本结构配置也使系统的外极线呈一系列的放射线，对应点匹配简单。此外两镜面的间隔安装也使得系统的等效基线较长，从而具有较高的精度。 本文第一部分对当前的各种全向成像方法进行了简单介绍，并对各方法的特点做了归纳。第二部分介绍折反射全向视觉的研究现状，就各种反射镜面的成像特点做了对比。 第三部分介绍OSVOD的设计方法，包括机构的设计和镜面的设计，并对设计的结果做了误差分析。 第四部分是OSVOD的标定研究。给出了一种包括OSVOD中相机和镜面位置关系在内的系统参数的标定方法。该方法利用空间坐标已知的标定点在像平面上成的像，结合系统成像模型反算出标定点的空间坐标，再利用标定点的已知空间坐标和反算出的空间坐标建立方程，运用基于Levenberg-Marquardt的反向传播算法(backpropagation)标定相机与反射镜面间的安装偏差。该标定方法可推广到所有的折反射成像系统。 第五部分是基于全向图像的匹配研究。针对系统获取的立体图像对之间成像比例存在较大的差异，首先将图像展开成柱面投影图像，然后就下镜面成像展开的柱面做Canny边缘检测，得到了图像的边缘点；就得到的边缘点在展开的两幅柱面图像上做直接相关匹配。最后将获取的匹配点做一致性校验，并对一致性校验通过的匹配点做三维计算，生产稀疏的三维图像。 最后是结论和将来的工作展望。

基于单相机的全向立体视觉关键技术研究

获取全向三维信息对移动机器人导航和行动规划具有重要意义。尽管有许多其他方法可以完成这一任务，如超声传感器和激光测距仪，但是折反射立体视觉系统在大多数情况下可以获得更高的精度和更大的视场，并且不消耗额外的能量。本文采用了一种新型的折反射全向立体视觉光学装置(OSVOD)进行立体视觉的研究，OSVOD是由两个双曲面镜和一个透视相机所组成的系统，能够由单幅图像实现立体视觉。 本文重点对单相机全向立体视觉系统的标定、单幅图像匹配、运动估计和多目匹配这三项最关键的技术进行了研究。在系统标定方面，给出了一种包括OSVOD中相机和镜面位置关系在内的系统参数的标定方法。该方法利用空间坐标已知的标定点在像平面上成的像，结合系统成像模型反算出标定点的空间坐标，再利用标定点的已知空间坐标和反算出的空间坐标建立方程，运用基于Levenberg-Marquardt的反向传播算法标定相机与反射镜面间的安装偏差。该标定方法可推广到所有的折反射成像系统。 在单幅图像匹配方面，针对系统获取的立体图像对之间成像比例存在较大的差异和畸变的问题，将图像展开成柱面投影图像和俯视投影图像，并提出了一种三步算法，首先匹配非歧义的点，从而将匹配划分为小的独立的子问题，并且每条极线只匹配到最远的特征点，从而避免在远端的不可靠匹配。在随后的动态规划算法中，设计了一个特定的能量函数，对不同的纹理强度和置信程度分别加权，得到了可靠的全向致密深度图。 在运动估计与多目匹配方面，以Harris角点做为待匹配的特征，由相关性得到初匹配结果。该结果中不可避免地存在误匹配，采用随机采样一致算法来得到运动估计。完成运动估计后，利用不同位置得到的图像进行了基于边缘检测的多目匹配，快速准确地获取了障碍物信息。

基于线性不变矩和角度向量的立体匹配算法

针对室内场景双目立体匹配有别于一般场景立体匹配的特殊性,提出了一种计算简便、准确度高的立体图像匹配算法。该算法首先利用canny算子检测物体的边缘,根据边缘的线性不变矩寻找出目标物体,然后提取出目标物体轮廓的特征点,利用角度直方图计算出左右图像的旋转角度,最后利用角度向量实现左右图像的对应像素点的匹配。线性不变矩有效地将计算复杂度由二维降低到一维,大大降低了计算量。角度向量的提出降低了特征点匹配的复杂度,而且计算简便,准确率高。实验表明,该算法对图像的缩放、旋转、平移均免疫,具有较高的识别精度和良好的抗干扰性,计算效率高于传统方法,有着较高的应用价值。

基于双目视觉的运动物体实时跟踪与测距

利用双目视觉信息系统实现三维空间中运动物体实时跟踪与测距。当运动目标超出视野范围时,可通过控制摄像机云台转动搜索目标。此外,还研究了在摄像头运动情况下,无需重新标定,即可实现运动物体测距的算法。这里,自适应背景建模法与CamShift算法用于实现运动物体的辨识与跟踪。实验结果证明了所提出的算法能够有效地追踪物体,并同时准确地测量它的三维位置。

基于双目重建不确定性的动态特征滤除

提出了一种基于双目视觉三维重建不确定性的环境动态特征滤除方法。针对利用立体视觉系统对机器人进行运动估计时,环境中的动态目标和环境静态背景与机器人的空间相对运动具有不一致性,将严重影响系统的精度的问题。根据动态目标与环境背景的空间运动不一致性,分析立体视觉三维重建的不确定性,利用重建的不确定性估计机器人与环境间的相对运动,通过随机一致性方法(RANSAC)滤除图像中的环境动态特征。仿真实验结果表明了本方法的可行性和有效性。