基于三角网格模型的文物几何信息计算

发布时间：2018-01-05 12:20

本文关键词：基于三角网格模型的文物几何信息计算　出处：《北京建筑工程学院》2012年硕士论文　论文类型：学位论文

【摘要】：古文物是一个国家和民族在一个特定时期的政治、经济、文化的体现，然而由于自然环境和人类的活动影响，许多历史文物正逐渐遭受破坏或消失。利用新技术手段进行文物原貌永久保留、文物修复等工作已经成为全球性热点研究问题。由于数据获取设备和计算机技术的发展，为文物的保护工作开创了一个全新的局面。文物的保护工作也有了全新的进展，文物保护工作不仅要实现文物原貌三维信息永久保留，并将三维场景虚拟展示在人们面前，更要为文物的修复提供科学的数据。一些文物结构非常复杂，，表面呈不规则形状，传统测量方法无法得到全面而详细的文物三维几何信息，而且自动化程度不高，在快速获得高精度的文物表面数据方面显得不足。近年来不断发展和成熟的三维激光扫描技术，给文物保护工作提供了新的研究思路。通过三维扫描手段，获得文物几何和纹理等信息数据，再通过成熟的数据处理软件，重构文物三维模型。在文物修复中经常需要估算修复材料的用量，以文物三维模型为基础，通过计算不规则表面文物模型的体积、表面积以及缺损面积，为文物的修复提供重要的数据支持。为了能对文物模型的轮廓特征直观详细地了解，可用平面对文物模型剖切，提取剖面轮廓线，剖面轮廓线能够为文物研究者分析文物的轮廓特征提供依据。本文的主要研究内容有： 1.根据三角网格中边界边的性质进行边界的提取，为了区分孔洞边界和非封闭模型的外边界，给出通过判断法向量方向来区分这两类边界的方法，实现了三维孔洞面积的计算。 2.改进了利用有符号四面体体积法计算网格模型的体积的算法，实现了不规则表面文物模型的体积的精确计算。实现了模型的表面积计算。 3.提取模型的剖面轮廓线。对模型的剖切算法进行了改进，预先将三角形在剖切方向上分组，判断剖切平面和模型中的三角形的位置关系，计算交点，并将交线按拓扑关系进行排序等，从而提取封闭的剖面轮廓线。 4.开发了三维模型可视化量算系统。利用OpenGL的拾取模式，用鼠标在模型上任选感兴趣区域，计算选定区域的面积，查询模型上任意点的三维坐标，计算模型上任意两点之间的距离。从而实现三维信息的提取。在三维模型的基础上，计算文物三维几何信息的方式，可以间接而且无损的获取文物模型的孔洞边界、体积、面积、剖面特征等几何信息，以及直接在模型上选定区域并计算被选定区域的面积，查询任意点的坐标信息等，这些重要的几何信息数据，能够为文物的修复提供科学的数据。
[Abstract]:Ancient cultural relics are the embodiment of politics, economy and culture of a country and nation in a specific period, however, due to the influence of natural environment and human activities. Many historical relics are gradually being destroyed or disappearing. The use of new technology means the permanent preservation of the original appearance of cultural relics. The restoration of cultural relics has become a global hot research issue due to the development of data acquisition equipment and computer technology. For the protection of cultural relics to create a new situation. The protection of cultural relics has also made a new progress, cultural relics protection work not only to achieve the preservation of three-dimensional information on the original appearance of cultural relics. And the three-dimensional scene virtual display in front of people, but also for the restoration of cultural relics to provide scientific data. Some cultural relic structures are very complex, the surface is irregular, the traditional measurement method can not get comprehensive and detailed three-dimensional geometric information of cultural relics, and the degree of automation is not high. In recent years, the continuous development and mature three-dimensional laser scanning technology, for the protection of cultural relics to provide a new way of thinking, through three-dimensional scanning means. Through the mature data processing software, the 3D model of cultural relic is reconstructed. It is often necessary to estimate the amount of restoration material in the restoration of cultural relic, which is based on the 3D model of cultural relic. By calculating the volume, surface area and defect area of the irregular surface cultural relic model, this paper provides important data support for the restoration of the cultural relic, in order to understand the contour features of the cultural relic model in detail and intuitively. The cultural relic model can be cut by plane, and the profile line can be extracted, which can provide the basis for cultural relic researchers to analyze the contour characteristics of cultural relics. The main contents of this paper are as follows: 1. According to the properties of boundary edges in triangular meshes, in order to distinguish the boundary between the hole boundary and the outer boundary of the unclosed model, a method to distinguish the two kinds of boundaries by judging the normal vector direction is presented. The calculation of three-dimensional hole area is realized. 2. An improved algorithm for calculating the volume of the grid model by means of the signed tetrahedron volume method is presented, which realizes the accurate calculation of the volume of the model of irregular surface relics and the calculation of the surface area of the model. 3. Extract the profile of the model, improve the algorithm of the model, group the triangles in the cutting direction in advance, judge the position relation between the cutting plane and the triangle in the model, and calculate the intersection point. The intersection line is sorted according to topological relation, and the closed profile is extracted. 4. The visualization calculation system of 3D model is developed. The area of selected area is calculated by using the picking mode of OpenGL and using the mouse to select the region of interest on the model. The 3D coordinates of any point on the model are queried and the distance between any two points on the model is calculated. On the basis of 3D model, the method of calculating 3D geometric information of cultural relic can obtain the geometric information of hole boundary, volume, area, profile and so on indirectly and unscathed. The important geometric information data can provide scientific data for the restoration of cultural relics, such as selecting the region directly on the model, calculating the area of the selected area, querying the coordinate information of any point, etc.
【学位授予单位】：北京建筑工程学院
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：K87;TP391.41

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