面向移动终端的三维植物模型简化与重构技术研究

发布时间：2018-05-15 10:09

本文选题：移动终端 + 三维树木简化　；参考：《浙江工业大学》2013年硕士论文

【摘要】：近年来,以智能手机、平板电脑等为典型代表的移动设备得到迅速普及,其使用数量己经超出传统的个人计算机,预计在不久的将来其将获得比传统个人计算机更加广泛的应用空间。面向资源受限的移动设备的各种三维应用场景也在日益增多,如三维游戏、虚拟展示、电影特技、定位服务、动画和广告等。树木不仅在现实生活环境中随处可见,而且是自然界不可缺少的一种植物类型,在一定程度上会对虚拟三维自然场景的沉浸感和逼真度产生重要影响。由于自然界中树木的形态各异、种类繁多、拓扑结构十分复杂,若想构建出视觉效果逼真的三维树木模型,其建模过程非常繁琐且十分耗时。同时,由于当前网络带宽、延时和拥塞等网络因素和移动终端硬件条件等因素的限制,严重影响了三维植物模型在移动终端应用中交互操作的实时性。针对上述问题,本文着重以三维植物模型中的树木模型为研究对象,开展面向移动终端的三维植物模型简化与重构技术研究。本文根据三维树木模型的拓扑结构特点,分别对模型的树枝和树冠部分进行简化,并在简化模型的基础上开展基于骨架个性化编辑的模型构建方法研究,主要工作和成果如下： (1)针对三维树木模型点和面的几何信息数据量大的问题,本文采用保持视觉重要度的总体模型简化策略。在该简化方法中,首先,将整体树木模型分成相互独立的枝干部分和树冠部分,并分别对两部分进行独立简化；然后,为了保留树木模型的视觉感知特性,本文结合模型视觉重要区域对模型采用不同等级的简化策略。这样既有效地简化了树木模型,加快了模型网络传输效率和渲染速度,又保持了树木模型原始视觉感知效果。 (2)枝干是三维树木模型的重要组成部分,同时也是影响模型整体拓扑结构形态的关键因素。因此,本文采用一种结合距离变换和形状分解的三维树木枝干模型简化方法。然后,利用基于圆台、梯形平面和插值的模型重构方法进行树木枝干模型重构。本文采用的方法不仅能够很好地提取原始树木模型的骨架结构,而且模型重构方法能够较好地还原树木的几何形态。因此,该方法能够有效地简化原始树木枝干面片信息,并且能够快速重构树木枝干模型。 (3)为了进一步简化三维树木模型的网格数量,减小模型网络传输时间和渲染时间,本文提出一种基于凸包纹理模板贴图的三维树木树冠模型简化与重构方法。该方法通过树冠的凸包来表示树冠的整体拓扑结构,并在已有的纹理模板库中寻找符合标准的枝叶模板进行填充,然后根据凸包所形成的几何空间重构三维模型的树冠,从而达到对树冠部分的几何信息简化的目的。 (4)为了能够快速且多样化地构建面向移动终端的三维树木模型,本文提出一种支持骨架个性化编辑的树木模型构建方法。其本质是在简化的树木模型骨架结构的基础上,通过人机交互个性化编辑树木模型骨架细节,使其形成具有全新骨架结构的树木模型。利用树木模型重构技术,最终实现三维树木模型的快速构建。通过实验表明,该方法能够快速建模同一品种树木不同表现形态的简化模型。 (5)为了验证本文提出的模型简化和个性化编辑方法的有效性,本文设计和实现了三维树木模型简化和个性化编辑系统。树木模型简化和个性化编辑功能由系统交互层的PC端实现,将原始模型简化和交互式个性化编辑后存储至服务器中。移动终端可以根据需要下载树木模型文件,并在终端上进行渲染和漫游。
[Abstract]:In recent years , mobile devices , such as smartphones , tablets , etc . , have been rapidly popularized . Their use has been more extensive than that of traditional personal computers .

( 1 ) Aiming at the problem of large amount of geometric information of three - dimensional tree model points and faces , the overall model simplification strategy is adopted to maintain the importance of vision . In this simplified method , firstly , the whole tree model is divided into branches and crown parts which are independent from each other , and the two parts are independently simplified ;
Then , in order to preserve the visual perception characteristics of the tree model , a simplified strategy of different levels is applied to the model based on the important regional model of the model , which effectively simplifies the tree model , accelerates the transmission efficiency and the rendering speed of the model network , and maintains the original visual perception effect of the tree model .

( 2 ) The branch stem is an important part of the three - dimensional tree model , and it is the key factor that affects the overall topological structure of the model .

( 3 ) In order to further simplify the mesh number of the three - dimensional tree model and reduce the transmission time and rendering time of the model network , this paper presents a method for simplifying and reconstructing a three - dimensional tree crown model based on a convex hull texture template map . The method uses the convex hull of the crown to represent the whole topological structure of the crown , and finds out the tree crown of the three - dimensional model according to the geometric space formed by the convex hull , thereby achieving the purpose of simplifying the geometric information of the crown part .

( 4 ) In order to construct a three - dimensional tree model facing the mobile terminal rapidly and diversified , a tree model building method supporting personalized editing of skeleton is presented in this paper .

( 5 ) In order to validate the model simplification and personalized editing method proposed in this paper , a three - dimensional tree model simplification and personalized editing system is designed and realized . The tree model simplification and personalized editing function are realized by the PC end of the system interactive layer , and the original model is simplified and the interactive personalized editing is stored in the server . The mobile terminal can download the tree model file according to the need , and perform rendering and roaming on the terminal .

【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TP391.41

【参考文献】