共查询到19条相似文献,搜索用时 62 毫秒
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采用标记拼接的相位测量轮廓术 总被引:1,自引:0,他引:1
提出一种采用标记拼接的新的光学三维传感方法。在采用结构照明的光学三维传感中,阴影及条纹错位关系到被测量物体三维面形重建的质量。在处理阴影时,传统方法是采用插值方法,在处理条纹错位时,通常采用增大条纹周期或采用几组条纹周期不同的光波进行投影,这样通常降低了测量精度。为了提高测量精度,本文提出一种在同一参考面内,采用单组相移正弦条纹进行投影,通过旋转被测物体,并对旋转前后两次重建物体在信息可靠区域内进行标记拼接,恢复物体表面完整三维信息的方法。实验证实了此方法的有效性及实用性。 相似文献
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由序列图像进行三维测量的新方法 总被引:2,自引:2,他引:0
目前的三维测量方法都需要专门的测量设备且存在着种种限制,为此提出了一种基于图像序列进行三维测量的新方法。将由数码相机围绕被测物体拍摄的多幅图像导入计算机,利用图像处理知识得到特征的二维信息;采用计算机视觉方法,对特征从射影空间到欧式空间分层逐步重建即可完成三维测量。设计一套特征标志组合,作为辅助测量工具避免了特征匹配难题。确立了一套图像分割与识别策略获得特征标志二维信息,识别率可达到95%以上。采用基于模约束的摄像机分层自标定方法得到特征在欧式空间下的三维信息,并通过多种优化方法减少误差的影响。该方法在硬件上实现简单,对测量条件要求不高。实际试验表明,相对误差可达到1.48%,重投影误差为0.3864像素。 相似文献
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为实现基于图像的飞秒激光烧蚀硅晶片光斑阵列的完整测量,对采集的多幅光斑阵列图像拼接,得到完整的飞秒激光烧蚀光斑阵列图像。首先,对飞秒激光烧蚀光斑图像进行增强处理,对光斑进行方形拟合提取中心点,获取每两个中心点间的像素值,运用线纹对微视觉测量系统标定,获得像素尺寸与几何尺寸之间的比例系数,根据比例系数对像素尺寸与几何尺寸进行换算,得到对光斑阵列的视觉测量值;最后,用拼接后的光斑阵列进行图像测量,得到测量尺寸与实际尺寸间的误差平均值为3.00%。经实验验证,利用图像拼接对微视觉系统大视场微结构进行图像测量是可行的。 相似文献
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针对单幅CCD相机所获指针式表盘图像存在的视角误差问题,提出了基于SIFT(尺度不变特征变换)的图像拼接方法,将分别准确获取的标准器与被检器示值图像进行无缝拼接,并通过实验验证了方法的有效性和可行性。 相似文献
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采用标记条纹跟踪的冲击过程三维轮廓术 总被引:2,自引:0,他引:2
针对在冲击、爆轰等快变化过程的三维轮廓术中,CCD拍摄速度低于物体的运动速度而导致对动态条纹的时间采样不足和物体表面发生破裂而分成数块的动态过程,提出一种采用标记条纹进行跟踪的动态过程三维轮廓术.以傅里叶变换轮廓术为基础,通过采用标记条纹进行跟踪锁定变形条纹中同级次条纹的变化以及Gerchberg迭代算法在破裂区域迭代生成伪条纹,对破裂表面分块进行处理,有效地解决了在快变化动态过程的三维重建中因时间采样不足和条纹断裂对三维相位场的展开所带来的问题,获得了物体正确的面形分布.实验证实了此种方法的正确性. 相似文献
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《成像科学杂志》2013,61(4):351-360
AbstractThis work describes the investigation into a new 3D capture method for acquisition and subsequent forensic analysis of bite mark injuries on human skin. When documenting bite marks with standard 2D cameras, errors in photographic technique can occur if best practice is not followed. Subsequent forensic analysis of the mark is problematic when a 3D structure is recorded in a 2D space. A 3D image capture and processing system might avoid the problems resulting from the 2D reduction process, simplifying the guidelines and reducing errors. This paper reviews current 2D and three 3D capture methods and proposes a series of benchmarks for system assessment. This is followed by a series of performance evaluations of the existing current 2D and two 3D methods. Further proposed solutions include the design of a system specification for the practical reproducible acquisition of bite mark injuries and a review of the validation process for forensic evidence presented to the courts. The result of this work is that a 3D system is required to produce the correct 3D data of a bite mark and suspect dentition for forensic analysis. Such a system should be practical and consistent if it is to replace the current de facto 2D systems. The MAVIS hardware, for example, can be considered a practical and consistent solution for producing the required 3D image of a bite mark for analysis; however, the MAVIS hardware cannot produce a satisfactory 3D image of a dental cast. At present, a laser scanner is required to produce satisfactory results of a dental cast. Angular distortion and errors created by the user in 2D image capture can hinder the digital measurement process. 3D capture therefore introduces less operator error in the form of angular distortion. 相似文献
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An effective mesh generation algorithm is proposed to construct mesh representations for arbitrary fractures in 3D rock masses. With the development of advanced imaging techniques, fractures in a rock mass can be clearly captured by a high‐resolution 3D digital image but with a huge data set. To reduce the data size, corresponding mesh substitutes are required in both visualization and numerical analysis. Fractures in rocks are naturally complicated. They may meet at arbitrary angles at junctions, which could derive topological defects, geometric errors or local connectivity flaws on mesh models. A junction weight is proposed and applied to distinguish fracture junctions from surfaces by an adequate threshold. We take account of fracture junctions and generate an initial surface mesh by a simplified centroidal Voronoi diagram. To further repair the initial mesh, an innovative umbrella operation is designed and adopted to correct mesh topology structures and preserve junction geometry features. Constrained with the aforementioned surface mesh of fracture, a tetrahedral mesh is generated and substituted for the 3D image model to be involved in future numerical analysis. Finally, we take two fractured rock samples as application examples to demonstrate the usefulness and capability of the proposed meshing approach. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Nanda K. Surendran Xun W. Xu Oliver Stead Heather Silyn‐Roberts 《International journal of imaging systems and technology》2009,19(3):244-259
Three‐dimensional (3D) digitization is a key aspect in the preservation and exhibition of museum artifacts. The objective of this article is to investigate contemporary technologies for creating accurate 3D digital models of artifacts from the Maori and Pacific heritage and to establish a generic digitization methodology so that the 3D models can be archived and exhibited both over the internet and within museum displays. This process involves procedures for selecting artifacts that are suitable for laser scanning and then setting up the artifact for scanning. This is followed by the actual scanning and postprocessing stages. To achieve this, the Polhemus FastSCAN laser scanner has been used to collect raw point cloud surface data from artifacts of various sizes, shapes, textures, colors, and materials. The article explains the generic steps developed for postprocessing of raw scan data in the form of a cloud of geometric data points to a completely rendered 3D model with colors mapped on to the model. These generic steps involve removal of background noise, enhancement of texture, filling of holes, merging of separate scans, and color mapping. The results from the scanning and postprocessing of a wahaika, (a Maori club‐like weapon) and a Polynesian stone pounder reveal that it is important to use a scanner that is flexible enough to capture all the surface information irrespective of the artifact's geometry, and one with the capability of capturing color information with high accuracy. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 244–259, 2009 相似文献
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三维表面粗糙度参数的矩表征 总被引:1,自引:0,他引:1
以分形几何理论为基础,利用轮廓谱矩和表面谱矩对三维表面粗糙度评定参数进行了分形表征;并且从理论上提出了一些新的三维评定参数,如均一性、等方性等;最后还进行了实验验证。 相似文献
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提出了一种适用于任意多层电介质分层结构中的3D互连电容参数提取的新方法--反射镜像法.该方法无需对格林函数进行推导,而是根据自由电荷反射原理计算反射镜像的位置和镜像电荷系数从而获得各级镜像分布,继而计算任意多层电介质环境下的3D电容,包括底层或顶层介质接地情况下的3D电容.该方法可克服级数形式的格林函数因受限于电介质分层数目而难以适应大规模集成电路中复杂多变电介质环境下的3D电容参数提取问题.通过对导体面元建立层次式数据结构,这一方法可以利用层次式算法(hierarchical method)实现计算加速.实验证明,该方法能在保证可靠精度的情况下达到迅速收敛,与层次式加速算法结合后,计算效率可达到FastCap法的数倍. 相似文献
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利用菲涅尔波带法计算三维全息 总被引:1,自引:1,他引:1
根据全息理论,从点光源菲涅尔全息图的计算出发,提出一种利用主菲涅尔波带计算三维物体菲涅尔全息图的方法。通过读取 3DS 文件直接获得三维物体表面各点的空间位置信息,模仿物理全息计算出点的菲涅尔图,将组成三维物体的各点的菲涅尔波带叠加从而获得三维物体的全息图。该方法区别于用菲涅尔衍射公式的传统全息计算,用加法运算代替指数、乘除运算,从而大大加快了计算输出全息图的速度,且具有信息连续、无冗余信息等特点。实验对由 1060 个采样点组成的物体进行全息计算,生成一幅 1024×768 的全息图,所需时间为 83s。 相似文献