發(fā)布時(shí)間：2018-10-15 15:47

【摘要】：隨著空間數(shù)據(jù)采集技術(shù)的飛速發(fā)展和全球經(jīng)濟(jì)一體化的不斷深入,許多應(yīng)用領(lǐng)域越來(lái)越頻繁地使用大范圍(甚至全球)高分辨率地形數(shù)據(jù)進(jìn)行分析決策。但是,由于受當(dāng)前的計(jì)算機(jī)硬件限制,為了提高顯示效率并實(shí)現(xiàn)DEM數(shù)據(jù)的無(wú)縫繪制和渲染,就需要在保證地形精度的前提下進(jìn)行DEM格網(wǎng)簡(jiǎn)化,即構(gòu)建多分辨率DEM表達(dá)模型。以傳統(tǒng)四叉樹(shù)結(jié)構(gòu)或二叉樹(shù)結(jié)構(gòu)作為多分辨率格網(wǎng)的剖分結(jié)構(gòu),不可避免在相鄰不同分辨率DEM格網(wǎng)之間產(chǎn)生裂縫,而目前的裂縫消除方法大都屬于“后期處理”,且這些方法會(huì)帶來(lái)新問(wèn)題,如地形失真、計(jì)算量大、破壞細(xì)分準(zhǔn)則、地形簡(jiǎn)化算法復(fù)雜化、數(shù)據(jù)管理復(fù)雜等等。多分辨率半邊結(jié)構(gòu)以多分辨率組合映射為基礎(chǔ)模型,是半邊結(jié)構(gòu)在多分辨率表達(dá)方面的擴(kuò)展。該理論將格網(wǎng)抽象為dart集合,幾何實(shí)體的構(gòu)建和拓?fù)潢P(guān)系表達(dá)均由dart的復(fù)合運(yùn)算實(shí)現(xiàn)。該結(jié)構(gòu)在實(shí)現(xiàn)格網(wǎng)多分辨率剖分時(shí),直接對(duì)邊管理,可以實(shí)現(xiàn)邊、面同步剖分。為此,本文引入多分辨率組合映射理論,提出一種基于多分辨率半邊結(jié)構(gòu)的多分辨率DEM無(wú)縫表達(dá)方法,有望從前期的格網(wǎng)剖分結(jié)構(gòu)層面消除地形多分辨率表達(dá)中的裂縫問(wèn)題。多分辨率半邊結(jié)構(gòu)在多分辨率格網(wǎng)的無(wú)縫表達(dá)方面具有優(yōu)勢(shì),但基于該結(jié)構(gòu)的研究仍處于初級(jí)階段,為了實(shí)現(xiàn)大規(guī)模甚至全球地形多分辨率建模,本文對(duì)其在全球多分辨率地形無(wú)縫建模的部分關(guān)鍵技術(shù)、操作算法和應(yīng)用進(jìn)行較為深入探討,主要工作及成果總結(jié)如下:1)梳理基礎(chǔ)理論及總結(jié)現(xiàn)有研究成果多分辨率組合映射是多分辨率半邊的理論模型,本文以多分辨率組合映射為核心,厘清了相關(guān)理論間的關(guān)系,包括半邊結(jié)構(gòu)、組合映射、超映射、多分辨率半邊結(jié)構(gòu);而后將該理論用于GIS中基本實(shí)體和空間關(guān)系的表達(dá),為該理論應(yīng)用于多分辨率DEM無(wú)縫表達(dá)奠定基礎(chǔ);分析了空間復(fù)雜度和鄰近搜索時(shí)間復(fù)雜了,并對(duì)該結(jié)構(gòu)的優(yōu)缺點(diǎn)進(jìn)行了分析和總結(jié)。在此基礎(chǔ)上,從多分辨率組合映射的基本理論、相關(guān)技術(shù)和算法等方面,扼要而全面的敘述了近年來(lái)國(guó)內(nèi)外的研究成果。研究發(fā)現(xiàn),在基本理論方面,多分辨率組合映射的理論較為完善,但并非盡善盡美,且缺乏應(yīng)用;在表面格網(wǎng)多分辨率表達(dá)方面,相關(guān)研究?jī)H限于細(xì)分原理和存儲(chǔ)方法,未對(duì)關(guān)鍵技術(shù)和建模算法進(jìn)行研究;當(dāng)該理論應(yīng)用到本文,處理大規(guī)模或全球地形數(shù)據(jù)時(shí),還會(huì)涉及四分體間裂縫、塊間裂縫、數(shù)據(jù)組織等方面的問(wèn)題。在以上問(wèn)題的基礎(chǔ)上,引出本文的研究?jī)?nèi)容和思路,并提出研究方案和技術(shù)路線。2)構(gòu)建了基于多分辨率半邊的多尺度DEM無(wú)縫表達(dá)算法樹(shù)結(jié)構(gòu)只對(duì)格網(wǎng)面細(xì)分,未對(duì)格網(wǎng)邊管理,不可避免在不同層次相鄰格網(wǎng)邊界處產(chǎn)生裂縫問(wèn)題。因此,引入多分辨率組合映射理論,提出一種基于多分辨率半邊結(jié)構(gòu)的多尺度dem無(wú)縫建模方法。首先,給出規(guī)則格網(wǎng)的多分辨率半邊剖分原理和存儲(chǔ)機(jī)制;然后,提出局部地形規(guī)則格網(wǎng)的多尺度dem的無(wú)縫建模算法。該算法從前期的格網(wǎng)剖分結(jié)構(gòu)上解決了多分辨率dem表達(dá)中的裂縫問(wèn)題,不需要限制相鄰格網(wǎng)的剖分層差,數(shù)據(jù)無(wú)冗余,地形無(wú)失真,可實(shí)現(xiàn)完全依據(jù)地形起伏的簡(jiǎn)化,能夠自適應(yīng)的管理簡(jiǎn)化后的多邊形格網(wǎng)。3)設(shè)計(jì)與實(shí)現(xiàn)了全球多分辨率地形無(wú)縫表達(dá)全球離散格網(wǎng)是全球地形表達(dá)的有效模型,全球多分辨率dem的裂縫不僅出現(xiàn)在單個(gè)四分體內(nèi)部,還見(jiàn)于四分體之間,盡管目前的裂縫消除方法有很多種,但大都屬于“后期處理”,且存在諸多限制。因此,本文將基于多分辨率半邊的局部地形多尺度dem無(wú)縫建模算法擴(kuò)展到全球范圍。首先,給出基于多分辨率半邊的多種全球離散格網(wǎng)統(tǒng)一表達(dá)原理;然后,以球面菱形格網(wǎng)為例,提出了菱形格網(wǎng)的多分辨率半邊剖分、編碼、編碼坐標(biāo)與經(jīng)緯度坐標(biāo)之間的轉(zhuǎn)化和全球菱形格網(wǎng)點(diǎn)高程值獲取等方法;最后,基于以上方法,設(shè)計(jì)并實(shí)現(xiàn)了全球多分辨率dem無(wú)縫建模算法。4)實(shí)現(xiàn)了全球多分辨率地形的動(dòng)態(tài)lod管理模擬與可視化為了實(shí)現(xiàn)全球高分辨率地形的無(wú)縫模擬和可視化,提出基于多分辨率半邊和菱形塊的全球多分辨率地形動(dòng)態(tài)lod管理模擬和可視化方法。首先,提出了塊間裂縫的消除方法,包括塊邊界結(jié)點(diǎn)、極點(diǎn)結(jié)點(diǎn)和塊頂點(diǎn)處結(jié)點(diǎn);然后,對(duì)全球地形數(shù)據(jù)進(jìn)行分塊組織,基于塊構(gòu)建多分辨率半邊結(jié)構(gòu),并應(yīng)用動(dòng)態(tài)調(diào)度方法,實(shí)現(xiàn)了全球多分辨率地形的動(dòng)態(tài)lod無(wú)縫表達(dá)。多分辨率半邊結(jié)構(gòu)可以保證塊內(nèi)無(wú)縫細(xì)分,塊間裂縫的消除比傳統(tǒng)方法簡(jiǎn)單;塊內(nèi)簡(jiǎn)化依據(jù)地形起伏,不存在數(shù)據(jù)冗余;不涉及塊間高程點(diǎn)的調(diào)整,地形無(wú)失真。5)設(shè)計(jì)并開(kāi)發(fā)了實(shí)驗(yàn)原型系統(tǒng)以c++語(yǔ)言和directx為工具,應(yīng)用全球gtopo30及局部地形高程數(shù)據(jù),應(yīng)用本文提出的算法,設(shè)計(jì)和開(kāi)發(fā)相應(yīng)的實(shí)驗(yàn)系統(tǒng),驗(yàn)證本文算法的正確性、可行性和有效性。該系統(tǒng)的主要功能包括:本文所提算法的實(shí)現(xiàn),包括局部地形無(wú)縫建模算法、全球多分辨率dem無(wú)縫建模算法和基于塊的動(dòng)態(tài)lod建模算法;算法運(yùn)行結(jié)果的數(shù)據(jù)統(tǒng)計(jì)分析,包括存儲(chǔ)元素、渲染三角形個(gè)數(shù)和四邊形個(gè)數(shù)等;可視化互操作,包括圖形的放大、縮小、旋轉(zhuǎn)等操作;地形數(shù)據(jù)文件的讀取和輸出。局部區(qū)域地形格網(wǎng)自適應(yīng)無(wú)縫建模實(shí)驗(yàn)結(jié)果表明:本文方法能夠?qū)崿F(xiàn)多尺度dem無(wú)縫建模,且與“限定四叉樹(shù)”法相比,隨剖分層次的增加,格網(wǎng)數(shù)量和渲染數(shù)據(jù)量的降低率逐漸增大,當(dāng)剖分層次為7時(shí),以上兩個(gè)指標(biāo)分別為13.9%和12.2%,優(yōu)于“限定四叉樹(shù)”法。該研究為多分辨率組合映射理論應(yīng)用于全球多分辨率dem無(wú)縫表達(dá)奠定了基礎(chǔ)。全球多分辨率DEM無(wú)縫建模實(shí)驗(yàn)結(jié)果表明:以多分辨率半邊結(jié)構(gòu)為基礎(chǔ),通過(guò)邊界和極點(diǎn)處結(jié)點(diǎn)細(xì)分準(zhǔn)則的特殊處理,四分體內(nèi)部、邊界和極點(diǎn)處均不會(huì)產(chǎn)生裂縫;通過(guò)調(diào)整細(xì)分閾值ε、最大剖分層次Lmax、最小剖分層次Lmin等三個(gè)參數(shù),可分別實(shí)現(xiàn)陸地和海洋格網(wǎng)不同程度的簡(jiǎn)化;當(dāng)剖分層次為10,閾值為500米時(shí),“限定四叉樹(shù)”結(jié)構(gòu)比多分辨率半邊多渲染三角形91922個(gè),比例為15.11%。實(shí)現(xiàn)了全球多分辨率DEM的無(wú)縫可視化表達(dá),基本滿足了全球多分辨DEM建模對(duì)繪制速度和逼真度的要求。基于菱形塊的全球地形動(dòng)態(tài)LOD無(wú)縫建模實(shí)驗(yàn)表明:多分辨率半邊結(jié)構(gòu)可以保證塊內(nèi)無(wú)裂縫,塊間通過(guò)邊界結(jié)點(diǎn)細(xì)分方法的限制,菱形塊邊界處相鄰結(jié)點(diǎn)同時(shí)剖分,對(duì)稱(chēng)分布,塊間無(wú)裂縫;與傳統(tǒng)方法相比,本文方法的簡(jiǎn)化效率更高,地形無(wú)失真,計(jì)算量小。
[Abstract]:With the rapid development of spatial data acquisition technology and the deepening of global economic integration, many fields of application increasingly use large-scale (even global) high-resolution terrain data for analysis and decision-making. However, due to the current computer hardware limitation, in order to improve the display efficiency and realize the seamless rendering and rendering of DEM data, it is necessary to simplify the DEM grid on the premise of ensuring the terrain precision, that is to construct a multi-resolution DEM expression model. As a cross-sectional structure of multi-resolution grid, the traditional four-fork tree structure or binary tree structure inevitably causes cracks between adjacent different resolution DEM grids, and the current crack elimination methods mostly belong to "Post-processing" and the method can bring new problems, such as terrain distortion, large calculation amount, breaking subdivision criterion, complicated terrain simplification algorithm, complex data management and the like. Multi-resolution half-side structure is based on multi-resolution combination mapping and is an extension of half structure in multi-resolution expression. According to the theory, the grid is abstracted into a dart set, and the construction of the geometric entity and the expression of the topological relation are all realized by the composite operation of the art. According to the structure, when the grid multi-resolution section is realized, the edge and the surface synchronization section can be realized directly on the edge management. To this end, the multi-resolution combined mapping theory is introduced in this paper, and a multi-resolution DEM seamless expression method based on multi-resolution half structure is proposed. The multi-resolution half-side structure has advantages in the seamless expression of multi-resolution grid, but the research on this structure is still in the primary stage. In order to realize multi-resolution modeling of large-scale and even global terrain, this paper is a key technology of seamless modeling of multi-resolution terrain in the world. The operation algorithms and applications are discussed in depth, the main work and results are summarized as follows: 1) The basic theory and summary of the existing multi-resolution combination mapping is the theoretical model of multi-resolution half, which is based on multi-resolution combination mapping. The relationship between the relevant theories is clarified, including the half structure, the combination mapping, the super-mapping and the multi-resolution half-half structure, and then the theory is applied to the expression of the basic entity and the space relation in the GIS, thus laying a foundation for the theory to be applied to the seamless expression of the multi-resolution DEM; The complexity of space complexity and adjacent search time is analyzed, and the advantages and disadvantages of the structure are analyzed and summarized. On this basis, from the aspects of the basic theory, correlation technique and algorithm of multi-resolution combination mapping, the research achievements at home and abroad in recent years are briefly described. It is found that in the basic theory, the theory of multi-resolution combination mapping is perfect, but not perfect and lacks the application; in the aspect of multi-resolution expression of the surface mesh, the relevant research is limited to the subdivision principle and the storage method, and the key technology and the modeling algorithm are not researched; When the theory is applied to this paper, when dealing with large-scale or global terrain data, it also concerns the problems of interquartic cracks, inter-block cracks, data organization and so on. On the basis of the above problems, this paper draws out the research content and thought of this paper, and puts forward the research scheme and the technical route. 2) The multi-scale DEM seamless expression algorithm tree structure based on multi-resolution half is constructed, the mesh surface subdivision is only subdivided, and the grid edge management is not carried out. crack problems are inevitably generated at adjacent grid boundaries at different levels. Therefore, the multi-resolution combined mapping theory is introduced, and a multi-scale dem seamless modeling method based on multi-resolution half structure is proposed. First, a multi-resolution half-section principle and storage mechanism of regular grid are given, then a seamless modeling algorithm of multi-scale dem of local terrain regular grid is proposed. The algorithm solves the crack problem in the multi-resolution dem expression from the prior grid section structure, does not need to limit the cross section difference of the adjacent grid, has no redundancy and no distortion of the terrain, and can realize the simplification of the topographic relief completely, the global discrete grid is the effective model for global terrain expression, and the crack of the global multi-resolution dem is not only found in the inner part of a single tetrad, but also between the four quadrants, Although there are many methods of crack elimination at present, most of them belong to "Post-processing" and there are a number of limitations. Therefore, this paper extends the local terrain multi-scale dem seamless modeling algorithm based on multi-resolution half to the global scope. Firstly, a multi-resolution half of the global discrete grid expression principle is given, and then a multi-resolution half section of a diamond grid is proposed based on the spherical diamond grid, and the coding is carried out. and finally, based on the above method, the global multi-resolution dem seamless modeling algorithm is designed and realized. 4) the dynamic lod management simulation and visualization of the global multi-resolution terrain are realized, so that seamless simulation and visualization of the global high-resolution terrain are realized, A global multi-resolution terrain dynamic lod management simulation and visualization method based on multi-resolution half and diamond block is proposed. firstly, a method for eliminating inter-block cracks is proposed, which comprises a block boundary node, a pole node and a node at the vertex of the block; then, the global terrain data is segmented, the multi-resolution half structure is constructed based on the block, and a dynamic scheduling method is applied, and the dynamic lod seamless expression of the global multi-resolution terrain is realized. The multi-resolution half-side structure can ensure the seamless subdivision in the block, the elimination of the inter-block cracks is simpler than the traditional method, the simplification of the block according to the topographic relief does not exist, the data redundancy does not exist, and the adjustment of the elevation points between the blocks is not involved, In this paper, we design and develop the experimental prototype system based on the cpr language and the direct tx as the tool, apply the global gtopo 30 and local terrain elevation data, apply the algorithm proposed in this paper, design and develop the corresponding experimental system, and verify the correctness, feasibility and validity of the algorithm. The main functions of the system include the realization of the proposed algorithm, including the local terrain seamless modeling algorithm, the global multi-resolution dem seamless modeling algorithm and the block-based dynamic lod modeling algorithm, the data statistical analysis of the algorithm operation result, including the storage element, the number of the rendered triangles and the number of quads, etc.; visual interoperability, including operations such as enlargement, reduction, rotation, etc. of graphics; and the reading and output of the terrain data file. The results of self-adaptive seamless modeling of local terrain mesh show that the method can realize the seamless modeling of multi-scale dem and "defining a four-prong tree" Compared with the method, the decreasing rate of the grid quantity and the rendered data volume gradually increases with the increase of the cross section level. When the split layer is 7, the above two indexes are 13. 9% and 12. 2%, respectively. "defining a four-prong tree" Law. This study laid the foundation for the application of multi-resolution combined mapping theory to the seamless expression of multi-resolution dem. The results of global multi-resolution DEM seamless modeling show that, on the basis of multi-resolution half structure, crack is not generated at the inner, boundary and pole of the tetrad through special treatment of node subdivision criterion at the boundary and the pole; by adjusting the subdivision threshold value, the maximum split level Lmax, three parameters such as the minimum split layer Lmin and the like can realize the simplification of different degrees of the land and the ocean grid respectively; when the split sub-level is 10, the threshold value is 500 meters, "defining a four-prong tree" The structure is more than half-resolution half-rendering triangle 91922, with a ratio of 15. 11%. the seamless visual representation of the global multi-resolution DEM is realized, and the requirements of global multi-resolution DEM modeling on drawing speed and fidelity are basically met. The global terrain dynamic LOD seamless modeling experiment based on diamond block shows that the multi-resolution half-side structure can ensure no crack in the block, the block passes through the limit of the boundary node subdivision method, the adjacent nodes at the diamond block boundary are simultaneously split, symmetrically distributed and no cracks exist between the blocks; compared with the traditional method, The simplified efficiency of the method is higher, the terrain is free of distortion, and the calculation amount is small.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)(北京)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P208

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