共查询到17条相似文献,搜索用时 156 毫秒
1.
2.
提取血管内超声(IVUS)图像的血管内腔轮廓对冠状动脉疾病的诊断有积极意义.本文提出了一种基于梯度矢量流(GVF)snake与多尺度分析的轮廓提取新方法.针对传统GVF snake的轮廓初始化、抑制噪声和伪像干扰两个难点,本文方法在如下两个方面进行了改进第一,利用序列图像的特性产生时间方差图并得到初始轮廓,从而实现轮廓提取过程的全自动化;第二,引入多尺度分析,使GVF snake在离散小波变换得到的多尺度图中形变,从而增强了算法的鲁棒性.对仿真图像和实际IVUS图像的实验表明,该方法在轮廓提取的精度方面优于传统的GVF snake方法. 相似文献
3.
基子CT图像快速成型数据的构建方法 总被引:1,自引:0,他引:1
本文针对医学CT图像数据,提出了由CT图像构建快速成型数据的建模方法,确定了CT图像处理方案,即通过对断层图像的预处理、滤波处理、数据提取,生成断层图像轮廓,继而通过对轮廓优化和轮廓冗余数据去除,得到用于三维重建的二维轮廓数据,并在此基础上构造出可直接用于快速原型制造的三维STL数字模型。本文所提出的方法能够大大提高快速医学模型的构建速度。 相似文献
4.
将快速成型技术运用于骨骼实体模型的三维重建研究中,以人体下肢股骨近端为例,通过对原始CT图像数据进行阈值分割,提取股骨近端轮廓曲线,拟合成数字模型.利用快速成型机可以将股骨近端的数字模型实体化,得到与实际骨骼拟合程度较高的实体模型. 相似文献
5.
基于特征的模型重建是结构类零件实体模型重建的一种重要方法。借鉴正向设计的思想,提出了通过创建截面轮廓线来重建一类具有复杂轮廓特征的方法:首先选取合适的轮廓截面并得到截面轮廓数据点,然后排序轮廓数据点、识别轮廓线型、拟合分段曲线以及提取约束关系,进而实现截面轮廓的约束拟舍,从而得到满足有效约束的截面轮廓线;将截面轮廓线以某种扫掠方式形成实体特征,根据特征之间的依赖关系,运用实体布尔操作将各实体特征“组合”为实体模型。重点研究并实现了其中的关键技术——基于约束的截面轮廓重建方法,并用实例验证了方法的有效性和稳定性。 相似文献
6.
7.
8.
本文针对医学CT图像数据,提出了由CT图像构建快速成型数据的建模方法,确定了CT图像处理方案,即通过对断层图像的预处理、滤波处理、数据提取,生成断层图像轮廓,继而通过对轮廓优化和轮廓冗余数据去除,得到用于三维重建的二维轮廓数据,并在此基础上构造出可直接用于快速原型制造的三维STL数字模型.本文所提出的方法能够大大提高快速医学模型的构建速度. 相似文献
9.
10.
针对颜色图像受光照及背景影响较大而较难识别目标的问题,利用深度图像作为目标载体,设计并实现了一种简单的目标识别方法。该方法主要包括深度图像的轮廓提取算法和基于轮廓特征识别两部分。先根据提取的轮廓计算矩信息得到图像质心坐标,再根据相机投影公式获得目标质心的真实相机坐标;提取轮廓的矩形描述子,组合轮廓不变矩特征和轮廓形态学特征成为目标的联合特征向量。针对不同的待识别目标,采集足够数量的训练样本,得到各目标的标准特征向量。最后实时提取场景目标的联合特征向量,计算场景目标特征向量与标准特征向量的最小欧式距离,进行识别判断。实验证明了该方法的快速、有效性。该方法应用在装载机械臂的室内移动机器人上,可实现目标定位、识别及抓取操作,具有一定的应用价值。 相似文献
11.
J. H. Ryu H. S. Kim K. H. Lee 《The International Journal of Advanced Manufacturing Technology》2004,24(1-2):112-119
This paper concerns contour-based algorithms for generating a 3D CAD model from medical images. The 3D model generated by contour-based algorithms can be used to generate CAM data for fabrication where the accuracy is of most concern. The overall procedure includes: (1) contour data extraction from medical images, (2) smoothing of the extracted contours, and (3) creation of a surface model from contours. For this, various methods should be applied to generate a high-quality surface model. The main contribution of this paper is to propose a new contour smoothing method, called bi-directional smoothing. The basic idea behind the proposed bi-directional smoothing method is to refine contours along both (u, v) parametric directions. Compared to conventional smoothing methods, the recontouring that comprises the first part of the method can prevent the shape of a contour from shrinking with a large number of iterations. Along with recontouring, a vertical connectivity estimation and a vertical smoothing method are also proposed. The overall procedure for this approach is demonstrated with an application example using CT images of a femur. 相似文献
12.
一种基于CT图像反求技术的实体几何造型方法 总被引:10,自引:0,他引:10
基于 CT图像的反求是反求工程中的重要内容 ,由 CT图像反求重建出的表面模型只包含了表面几何信息 ,而实体几何模型具有完备的几何和拓扑信息。针对 CAD造型系统中实体模型的特点 ,本文提出一种基于 CT图像反求技术的实体几何造型方法。应用 CT图像反求技术重建出物体的三维表面模型 ,在重建出的拟合曲面三角片序列的基础上 ,采用半边结构来表达重建的表面模型 ,并将该过程作为本研究所开发的特征造型原型系统 3D-Modeler2 .0中的一种造型方法 相似文献
13.
Rapid parametric design methods for shoe-last customization 总被引:1,自引:0,他引:1
Jin Wang Haining Zhang Guodong Lu Zheng Liu 《The International Journal of Advanced Manufacturing Technology》2011,54(1-4):173-186
With the development of computer-aided design (CAD) technology and increasing demands of customized footwear, shoe-lasts are requested to be designed rapidly so as to speed-up the process of footwear manufacturing. Thus, this study presents a CAD system for shoe-last rapid customized design based on the piecewise reconstruction to realize the interactive deformation and separate/global shoe-last form reuse. First, piecewise remodeling method is proposed based on the multi-layer parametric definition and contour curves are extracted from the mesh. Then, five types of proper constraints to support surface manipulation are proposed, and the draft-driven deformation by the contour curve bending can realize the interactive local surface design in free angle of view. Finally, shoe-last styles can be saved and reused globally or separately to share design results between different shoe-lasts. Experimental examples show that customized shoe-lasts can be easily and rapidly generated by adopting the parametric design methods. 相似文献
14.
15.
Qi Liwei Zhao Yi Li Minghui 《The International Journal of Advanced Manufacturing Technology》2004,24(5-6):335-344
By the layer-measuring methods of reverse engineering (RE) technology, such as industrial computed tomography (ICT), the geometrical data of a complex inner surface can be obtained. However, related researches, such as contour segmentation, 3-D model reconstruction, etc., need to be extensively carried out for industrial application. This paper intends to solve the problem of extracting contour segments corresponding to different types of surfaces/features from the layer-measuring data. In general, the extracting process can be divided into two stages: rough segmenting and refining. In the rough segmenting stage, an optimal contour matching method is put forward to find similar contour segments from another layer according to the seed contour. In the refining stage, different contour extracting methods are presented with respect to different types of surfaces. For polyhedral or rotational surfaces, an iterative way in which the feature contour can be extracted precisely is presented. For freeform surfaces, another approach is to detect the joining points between the target contour segment and others. The presented approaches can precisely extract open contour segments belonging to certain types of surfaces/features as demonstrated in the examples. Based on this paper, further research such as parameter identification of 3-D surfaces and CAD model creation can be conducted. 相似文献
16.
逆向工程技术已成为模具CAD/CAM的制造技术之一,以车灯罩壳模为例,首先利用三维激光测量仪对零件进行测量,获取三维点云数据,然后利用UG软件将得到的轮廓数据三维重构,得到实物原型的三维数字模型,最后进行模具CAD/CAM。采用逆向工程技术可以快速实现模具的设计与制造,同时大大缩短了整个产品的开发周期。 相似文献
17.
设计过程是一个复杂的创造性劳动的过程。利用CAD怎样实现这个过程,是目前人们所关注的问题。本文针对系列化产品的设计,对这个问题作了深入的探讨,提出了在产品系列化设计时实现这个过程的方法:在图形处理上采用(1)拓扑结构描述法,(2)尺寸变量跟踪法,(3)装配工艺尺寸和零件工艺尺寸的分别处理法,在数据处理上采用数据文件、变量块、数据库的综合运用法。 相似文献