本文選題：地學(xué)模擬 + 空間分析�。� 參考：《南京師范大學(xué)》2013年碩士論文

【摘要】：隨著計(jì)算機(jī)技術(shù)和數(shù)值模擬計(jì)算方法的發(fā)展,目前進(jìn)行地學(xué)機(jī)理與過(guò)程模擬的基本思路是對(duì)地理空間進(jìn)行二三維有限元網(wǎng)格離散,然后采用相關(guān)數(shù)值計(jì)算方法完成計(jì)算模擬,故有限元網(wǎng)格是開(kāi)展地學(xué)機(jī)理與過(guò)程模擬的基礎(chǔ)。同時(shí),有限元網(wǎng)格可支持緩沖區(qū)分析、疊加分析等傳統(tǒng)GIS空間分析,由此可見(jiàn),有限元網(wǎng)格在地學(xué)機(jī)理與過(guò)程模擬及傳統(tǒng)GIS空間分析中扮演著十分重要的角色。三維有限元網(wǎng)格中,六面體網(wǎng)格在單元數(shù)量、自由度及計(jì)算精度等方面具有明顯優(yōu)勢(shì),已成為應(yīng)用最廣泛的三維網(wǎng)格之一,也是保證高效開(kāi)展復(fù)雜地學(xué)研究的首選網(wǎng)格。然而,六面體網(wǎng)格生成一直是有限元等領(lǐng)域的難點(diǎn),同時(shí)由于地學(xué)研究對(duì)象通常具有邊界復(fù)雜、約束條件多等特點(diǎn),針對(duì)地學(xué)研究對(duì)象的六面體網(wǎng)格生成問(wèn)題仍未得到很好的解決,這導(dǎo)致六面體網(wǎng)格特別是非結(jié)構(gòu)化六面體網(wǎng)格在地學(xué)研究中的應(yīng)用尚且不足。 為滿足相關(guān)地學(xué)研究對(duì)六面體網(wǎng)格的需求,促進(jìn)以數(shù)值計(jì)算方法為基礎(chǔ)的地學(xué)模擬及傳統(tǒng)GIS空間分析的進(jìn)一步發(fā)展,本文開(kāi)展了面向地學(xué)研究的六面體網(wǎng)格生成方法研究,針對(duì)常見(jiàn)地學(xué)實(shí)體模型,研究了三維空間對(duì)象的結(jié)構(gòu)化與非結(jié)構(gòu)化六面體網(wǎng)格生成,取得的主要成果如下： (1)結(jié)合地學(xué)研究對(duì)象自身特點(diǎn),對(duì)傳統(tǒng)柵格法進(jìn)行擴(kuò)展,基于地學(xué)研究實(shí)體表面模型(含約束條件),通過(guò)設(shè)計(jì)幾何特征識(shí)別及約束處理機(jī)制,使其能顧及實(shí)體邊界特征及內(nèi)部約束點(diǎn)、約束線、約束面、約束洞等約束特征,在實(shí)體三維空間合理的生成高質(zhì)量的六面體網(wǎng)格,提高傳統(tǒng)柵格法邊界擬合及約束處理能力,最后,采用網(wǎng)格質(zhì)量?jī)?yōu)化算法提高網(wǎng)格生成質(zhì)量。 (2)開(kāi)展了基于Voronoi圖的三維實(shí)體中軸生成研究,首先從三維實(shí)體中采樣,然后計(jì)算采樣點(diǎn)集的Voronoi圖,最后利用兩個(gè)與采樣范圍及密度無(wú)關(guān)的過(guò)濾條件從生成的Voronoi圖中挑選出分布于實(shí)體中軸附近的Voronoi子集,實(shí)現(xiàn)三維實(shí)體中軸生成,為非結(jié)構(gòu)化六面體網(wǎng)格生成算法做準(zhǔn)備。 (3)結(jié)合傳統(tǒng)柵格法及AFT法的算法優(yōu)點(diǎn),引入水平集方法思想,將地學(xué)實(shí)體表面三角網(wǎng)模型作為數(shù)據(jù)源,以結(jié)合距離場(chǎng)的各級(jí)水平(前沿水平等值面)作為向?qū)?從內(nèi)部種子開(kāi)始,識(shí)別種子表面四邊形網(wǎng)格特征,然后利用網(wǎng)格推進(jìn)模板,在前沿水平等值面之間推進(jìn)生成非結(jié)構(gòu)化六面體網(wǎng)格,最后,通過(guò)網(wǎng)格質(zhì)量?jī)?yōu)化算法確保網(wǎng)格質(zhì)量。 本文以南京南站區(qū)域地質(zhì)體數(shù)據(jù)為實(shí)例進(jìn)行驗(yàn)證,驗(yàn)證結(jié)果證明本文研究算法可靠有效,可對(duì)一般地學(xué)實(shí)體全自動(dòng)進(jìn)行六面體網(wǎng)格生成,在一定程度上滿足地學(xué)機(jī)理與過(guò)程模擬分析及傳統(tǒng)GIS空間分析對(duì)六面體網(wǎng)格的需求。
[Abstract]:With the development of computer technology and numerical simulation methods, the basic idea of geoscientific mechanism and process simulation is to discretize the geographical space with two-dimensional finite element mesh, and then complete the calculation simulation by using the relevant numerical calculation method. Therefore, finite element mesh is the basis of geoscientific mechanism and process simulation. At the same time, finite element mesh can support traditional GIS spatial analysis, such as buffer analysis and superposition analysis. It can be seen that finite element mesh plays a very important role in geoscientific mechanism and process simulation and traditional GIS spatial analysis. Hexahedron mesh is one of the most widely used three-dimensional meshes, which has obvious advantages in element number, degree of freedom and computational accuracy. It is also the first choice to ensure the efficient research of complex geology. However, the generation of hexahedron mesh has always been a difficult point in the field of finite element analysis. The problem of hexahedron mesh generation for geoscience research objects is still not well solved. As a result, the application of hexahedron mesh, especially unstructured hexahedron grid, in geoscience research is still insufficient. To promote the further development of geoscience simulation based on numerical calculation method and spatial analysis of traditional GIS, this paper develops the research of hexahedron mesh generation method for geoscience research, aiming at the common geoscientific entity model. In this paper, the structured and unstructured hexahedron mesh generation of 3D spatial objects is studied. The main results are as follows: (1) the traditional grid method is extended by combining the characteristics of geoscientific objects. Based on the geoscientific study of solid surface model (including constraint conditions), the geometric feature recognition and constraint processing mechanism are designed to make it take into account the entity boundary features, internal constraint points, constraint lines, constraint surfaces, constraint holes, and so on. The high quality hexahedron mesh is generated reasonably in the solid three-dimensional space to improve the traditional grid method boundary fitting and constraint processing ability. Finally, The mesh quality optimization algorithm is used to improve the quality of mesh generation. (2) the research of generating the central axis of 3D entity based on Voronoi diagram is carried out. Firstly, samples are sampled from 3D entity, then the Voronoi diagram of sampling point set is calculated. Finally, two filtering conditions independent of sampling range and density are used to select the Voronoi subset distributed near the axis of the entity from the generated Voronoi diagram to realize the generation of the three-dimensional solid axis. In order to prepare for the unstructured hexahedron mesh generation algorithm, combining the advantages of the traditional grid method and the AFT method, the level set method is introduced, and the geo-entity surface triangular network model is used as the data source. The quadrilateral mesh features of the seed surface are identified by combining the various levels of the distance field (the front level isosurface) as a guide, and then the mesh propulsion template is used to identify the quadrilateral mesh features of the seed surface. The unstructured hexahedron mesh is generated between the front level isosurface. Finally, the mesh quality is ensured by the mesh quality optimization algorithm. This paper takes the regional geological body data of Nanjing South Railway Station as an example to verify the grid quality. The results show that the algorithm is reliable and effective, and it can generate hexahedron mesh automatically for general geo-entities. To some extent, it can meet the requirements of geoscience mechanism and process simulation analysis and traditional GIS spatial analysis for hexahedron mesh.
【學(xué)位授予單位】：南京師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：P208;TP391.7

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相關(guān)期刊論文 前1條

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本文編號(hào)：2007004