共查询到19条相似文献，搜索用时 218 毫秒
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空间与图形这一领域中有关图形的测量与计算方面的内容包括：一维的长度的认识,测量工具和度量单位．以及平面图形周长的计算：二维的面积的认识．测量工具和度量单位．以及平面图形面积的计算;三维的体积（容积）的认识．测量工具和度量单位．以及物体表面积和体积（容积）的计算。上述内容中的长度、面积和体积是最为基本的从一维到二维氲驯：堆的窿骨船舍官们旱一个有机的度量概念整体。 相似文献
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BSP树在计算机图形学中应用于视点运动三维场景显示的计算。一般BSP树以递归的方式对平面进行分割,但实际应用的三维场景复杂度较高,也就使得树的复杂度非常高,预处理时间长。文章针对三维场景模型渲染速度慢的问题,基于空间BSP树的理论基础,通过引入包围体的方法使场景中的物体能够快速实现空间二分树划分,进而提高渲染速度。通过实验比较直接渲染和包围体渲染的速度,验证了引入包围体能够缩小预处理时间,提高场景的渲染速度。 相似文献
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邓艳娟 《河北职业技术学院学报》2010,(2)
在仿射微分几何中,研究的重心是将有常截面曲率仿射度量的曲面(超曲面)进行分类。如果一中心仿射曲面的中心仿射度量为平坦的,并且其Fubini-Pick形式关于中心仿射度量是平行的,则称此曲面为标准超曲面,因此讨论并构造E4空间中的标准超曲面是重要的。 相似文献
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本文提出了一种真实感三维人脸自动建模方法,只需一张光照均匀的人脸正面头像,通过自动提取面部的关键特征点重建人脸的几何模型,最后从图像上获取面部纹理信息得到真实感的三维人脸。实验表明该方法能较真实有效地重建三维人脸。 相似文献
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唐淑萍 《西安文理学院学报》2023,(2):29-33
基于深度学习的图像重建方法，通过数据驱动的方式，可以从图像中学习其三维空间的语义特征，从中恢复出模型的三维形状.探究了3类基于深度学习的图像虚拟重建算法，并在公开数据集上对相应的重建方法进行了性能比较，发现生成模型比非生成模型更有利于重建.其中，基于生成对抗网络的融合重建算法表现最优.此外，还对多视图输入的数量以及重建模型的表示对重建结果的影响进行了分析.实验结果表明，视图越多，且重建模型为网格表示时，重建结果越好. 相似文献
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欧阳立 《新疆教育学院学报》1987,(3)
1.引言 按Felix Klein所给的定义,几何学可以用几何变换群来分类。几何图形,如曲线,曲面等等在一已知几何变换群G下不变性质的研究称为属于群G的几何学。如果G是射影,仿射或欧氏群,我们有相应的射影,仿射或欧氏几何学。 由有限次的平行射影即透视仿射的乘积便构成一个仿射。在仿射平面内所有仿射变换的集合构成群。这个群称为仿射群。在仿射群下几何图形有许多不变的性质和不变量,其中最重要的不变性是同素性和结合性,最重要的不变量是单比。 相似文献
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ZHOU Yong-jun KOU Xin-jian 《浙江大学学报(A卷英文版)》2007,8(10):1614-1623
This paper presents a practical iterative algorithm for two-view metric reconstruction without any prior knowledge about the scene and motion in a nonsingular geometry configuration. The principal point is assumed to locate at the image center with zero skew and the same aspect ratio, and the interior parameters are fixed, so the self-calibration becomes focal-length cali- bration. Existing focal length calibration methods are direct solutions of a quadric composed of fundamental matrix, which are sensitive to noise. A quaternion-based linear iterative Least-Square Method is proposed in this paper, and one-dimensional searching for optimal focal length in a constrained region instead of solving optimization problems with inequality constraints is applied to simplify the computation complexity, then unique rotational matrix and translate vector are recovered. Experiments with simulation data and real images are given to verify the algorithm. 相似文献
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Tomographic particle image velocimetry(Tomo-PIV) is a state-of-the-art experimental technique based on a method of optical tomography to achieve the three-dimensional(3D) reconstruction for threedimensional three-component(3D-3C) flow velocity measurements. 3D reconstruction for Tomo-PIV is carried out herein. Meanwhile, a 3D simplified tomographic reconstruction model reduced from a 3D volume light intensity field with 2D projection images into a 2D Tomo-slice plane with 1D projecting lines, i.e., simplifying this 3D reconstruction into a problem of 2D Tomo-slice plane reconstruction, is applied thereafter. Two kinds of the most well-known algebraic reconstruction techniques, algebraic reconstruction technique(ART) and multiple algebraic reconstruction technique(MART), are compared as well. The principles of the two reconstruction algorithms are discussed in detail, which has been performed by a series of simulation images, yielding the corresponding reconstruction images that show different features between the ART and MART algorithm, and then their advantages and disadvantages are discussed. Further discussions are made for the standard particle image reconstruction when the background noise of the pre-initial particle image has been removed. Results show that the particle image reconstruction has been greatly improved. The MART algorithm is much better than the ART. Furthermore, the computational analyses of two parameters(the particle density and the number of cameras), are performed to study their effects on the reconstruction. Lastly, the 3D volume particle field is reconstructed by using the improved algorithm based on the simplified 3D tomographic reconstruction model, which proves that the algorithm simplification is feasible and it can be applied to the reconstruction of 3D volume particle field in a Tomo-PIV system. 相似文献
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杨俊林 《内江师范学院学报》2012,27(2):61-66
通过对＂仿射变换＂、＂射影平面＂、＂交比＂、＂完全四点形＂、＂Pappus定理＂、＂二维射影坐标系＂、＂配极变换＂等知识点的初等几何背景追踪及教学法处理,呈现出上述知识点的教育形态.帮助学生内化高等几何的基本观念,提高理解层次,更好地引导学生提高运用高等几何的思想分析处理中学数学问题的能力. 相似文献
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Dong Sun Shin Hae Gwon Jang Sung Bae Hwang Dong‐Hwan Har Young Lae Moon Min Suk Chung 《Anatomical sciences education》2013,6(5):316-323
In the Visible Korean project, serially sectioned images of the pelvis were made from a female cadaver. Outlines of significant structures in the sectioned images were drawn and stacked to build surface models. To improve the accessibility and informational content of these data, a five‐step process was designed and implemented. First, 154 pelvic structures were outlined with additional surface reconstruction to prepare the image data. Second, the sectioned and outlined images (in a browsing software) as well as the surface models (in a PDF file) were placed on the Visible Korean homepage in a readily‐accessible format. Third, all image data were visualized with interactive elements to stimulate creative learning. Fourth, two‐dimensional (2D) images and three‐dimensional (3D) models were superimposed on one another to provide context and spatial information for students viewing these data. Fifth, images were designed such that structure names would be shown when the mouse pointer hovered over the 2D images or the 3D models. The state‐of‐the‐art sectioned images, outlined images, and surface models, arranged and systematized as described in this study, will aid students in understanding the anatomy of female pelvis. The graphic data accompanied by corresponding magnetic resonance images and computed tomographs are expected to promote the production of 3D simulators for clinical practice. Anat Sci Educ 6: 316–323. © 2013 American Association of Anatomists. 相似文献
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在3DSMAX中建立三维场景造型并进行材质编辑和渲染等处理后,把场景输出为vrml文件格式,在vrml软件中构建了一个虚报现实场景。虚拟现实场景能产一种生动逼真的效果,浏览者可以控制场景并与之进行交互,进入场景里面,真实感受视觉冲击。 相似文献
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纪永强 《湖州师范学院学报》2014,(8):1-6
利用代数方法给出了三维内积空间中正交变换的特征向量的几何意义,研究了三维内积空间R3中的旋转变换(正交变换)的特征向量只有一个实的特征向量,以及研究了空间中关于经过原点的平面的对称变换(正交变换)的特征向量就是该平面的法矢量和该平面上自原点出发的任意矢量,并且它们是互相垂直的. 相似文献
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In this paper, a novel reconstruction technique based on level set method and algebraic reconstruction technique is proposed for multiphase flow computed tomography (CT) system. The curvature-driven noise reduction method is inserted into the conventional iteration procedure of algebraic reconstruction technique to improve the image quality and convergence speed with limited projection data. By evolving the image as a set of iso-intensity contours after each updation, the sufficient number of iterations for acceptable results is reduced by 80%-90%, while the image quality is enhanced obviously. Quantitative evaluation of image quality is given by using both relative image error and correlation coefficient. The resultant images can be utilized to detect flow regimes for monitoring industrial multiphase flow. Laboratory results demonstrate the feasibility of the proposed method. Phantoms of four typical flow regimes can be reconstructed from few-view projection data efficiently, and the corresponding image errors and correlation coefficients are acceptable for the cases tested in this paper. 相似文献
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从矢量的内积A·B=(A,B)=〈A|B〉直接引入左矢、左矢和度规张量;从仿射坐标系中矢量A=A~Ke_K=(A·e~K)e_K之表示式引进相伴基矢与相伴关量;并从仿射坐标系之间的广义正交变换引进协变矢量与逆变矢量;由此证明,这些矢量是紧密联系的,既彼此对立又相互补充、既相互对应又彼此相伴。 相似文献
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A method of medical image segmentation based on support vector machine （SVM） for density estimation is presented. We used this estimator to construct a prior model of the image intensity and curvature profile of the structure from training images. When segmenting a novel image similar to the training images, the technique of narrow level set method is used. The higher dimensional surface evolution metric is defined by the prior model instead of by energy minimization function. This method offers several advantages. First, SVM for density estimation is consistent and its solution is sparse. Second, compared to the traditional level set methods, this method incorporates shape information on the object to be segmented into the segmentation process. Segmentation results are demonstrated on synthetic images, MR images and ultrasonic images. 相似文献