基于三维模型转换器的虚拟植物可视化

提出了一个基于三维器官模型转换器来实现虚拟植物生长可视化的方法。该转换器的主要功能是在虚拟植物生长可视化系统内导入由三维建模软件所构造的具有表面细节的植物器官模型,之后结合L系统,实现由植物生长规律指导下的虚拟植物生长过程的实时模拟。实验结果表明,该方法改善了原有的一些虚拟植物生长可视化系统只考虑对器官进行几何建模,而忽略器官表面细节导致的展现效果真实感显著差异的缺陷。     

虚拟植物整体生长研究现状与展望

农林业信息化将成为21t世纪的重要发展趋势,针对植物生长期长,解决问题要较长周期,通过计算机对植物生长进行建模与仿真,将为探索植物生命的奥秘和生长过程的规律,改善人类生存环境质量.为了节省人力资源,提出虚拟植物技术仿真研究,具有广泛的应用前景.简述了虚拟植物整体生长研究的意义,从根、冠关系和植物整体可视化方面阐述了目前虚拟植物整体生长的研究现状,并探讨了了虚拟植物整体生长研究的难点,并对虚拟植物整体生长研究的应用前景作了简要的展望.     

扦插植物地下组织构型建模与形态仿真

很多植物都采用扦插育苗,为实现扦插植物的工厂化繁殖,研究其地下组织的生长规律及可视化模拟模型是研发扦插育苗机械化装备的基础之一。为此,基于几何建模的方法,结合扦插植物的繁殖特点,对扦插植物地下组织的构型进行建模;采用VC++及Direct3D图形接口,开发扦插植物地下组织的三维可视化动态仿真程序,并以扦插蔷薇的地下组织为样本进行模拟。结果表明：模拟仿真图形与实际扦插蔷薇的地下组织形态特征相似度较高,模拟数值与实测结果的相对误差小于10%。该研究为植物构型建模仿真提供了一个新的方向。     

基于生长机的虚拟植物可视化技术研究

虚拟植物在真实再现植物生长过程及在精确农业、遥感监测等领域都有非常广阔的应用前景。本文从植物生长建模的角度出发,着重阐述了基于生长机的虚拟植物生长可视化方面采用的一些方法及关键技术,并在此基础上提出了有待进一步解决的主要问题。对虚拟植物生长的可视化技术在虚拟试验、农田管理、教学等方面的应用进行了展望。     

遮荫环境下的植物生长建模及仿真

为了解决遮荫环境下的植物对光照资源的竞争和分配问题,更真实地仿真自然界中植物的生长情况,而采用了一种基于FON(field-of-neighbourhood)模型的植物生长建模及仿真的方法.方法用FON模型描述植物对光照资源的需求范围,引入植物学中遮荫率因子作为影响光照强度的一个因素,并提出了一种基于计算阴影重叠区域面积的光照资源分配策略.在实现过程中建立了一个支持植物共享光照资源的生长仿真系统,给出了不同竞争地位的植物在共享光照资源上所表现出的生长情况的可视化结果,对计算机仿真植物生长以及指导农林生产方面都具有积极意义.     

基于构筑模型的植物动态生长研究

植物学家提出的23种结构定义了植物形态发生的方式和最终生长的形态,能够形象而准确地对植物形态发生进行归纳和分类,但缺乏对植物形态可视化表达的有效手段和方法。因此,本文为再现植物的动态生长过程,基于构筑模型,遵循双尺度自动机的基本原理,应用微分L-系统构建植物连续生长过程的动态模型,并在计算机进行了三维可视化实现。提出的方法拓展了构筑模型的应用,仿真结果表明该方法在植物形态的建模上确实行之有效。     

基于Open-L系统的植物结构功能模型研究

为了真实地模拟植物生长发育过程,引入了Open-L系统建模理论.在植物形态发生模型的基础上,根据植物生长时其形态与生理特性及环境之间的相互作用,构建了综合考虑植物结构与功能的虚拟植物模型,再根据该模型有效组织了植物生长过程中的数据信息,并建立植物生长的可视化流程.最后,开发一个原型系统验证了该模型的可行性和有效性.     

三维云的建模和绘制

本文对计算机图形学中三维云的建模和绘制技术进行了概述,主要介绍目前比较典型的基于个体生长的云建模技术和基于物理过程的云建模技术.对基于个体生长技术中比较成功的粒子系统模型、变形球模型、体元模型、过程纹理函数模型进行详细分析,并总结了它们的成果与不足,比较了它们的适用范围,为研究三维云可视化技术提供借鉴.     

虚拟现实中真实感树木的实时绘制

植物的模拟是运用计算机图形学的理论与方法对植物形态结构和生长过程进行仿真的技术,是当前虚拟现实研究的热门课题.分析了虚拟现实中虚拟植物仿真的具体问题,结合植物造型、植物绘制、植物的运动模拟,研究虚拟植物仿真的原理和实现方法.特别针对如何实现虚拟现实中真实感树木的实时绘制进行了详细的分析,从植物模型的实现、光照的实现、阴影的实现、优化技术等方面进行了详细的介绍,给出了可行的树木建模方法和实时绘制技术.     

基于环境敏感的植物动态生长模型研究*

在对林学中的植物生长模型和环境模型综合研究的基础上,提出了一个基于环境敏感的植物动态生长模型,并对此模型的原理和实现方法进行了分析和研究,最后通过相应的可视化技术将该模型应用于虚拟森林的动态仿真系统.     

RETRACTED ARTICLE: Texture-guided volumetric deformation and visualization using 3D moving least squares

Examining and manipulating the large volumetric data attract great interest for various applications. For such purpose, we first extend the 2D moving least squares (MLS) technique into 3D, and propose a texture-guided deformation technique for creating visualization styles through interactive manipulations of volumetric models using 3D MLS. Our framework includes focus+context (F+C) visualization for simultaneously showing the entire model after magnification, and the cut-away or illustrative visualization for providing a better understanding of anatomical and biological structures. Both visualization styles are widely applied in the graphics areas. We present a mechanism for defining features using high-dimensional texture information, and design an interface for visualizing, selecting and extracting features/objects of interest. Methods of the interactive or automatic generation of 3D control points are proposed for the flexible and plausible deformation. We describe a GPU-based implementation to achieve real-time performance of the deformation techniques and the manipulation operators. Different from physical deformation models, our framework is goal-oriented and user-guided. We demonstrate the robustness and efficiency of our framework using various volumetric datasets.     

Topology based 2D engineering drawing and 3D model matching for process plant

Process plant models mainly include 3D models and 2D engineering drawings. Matching calculation between these CAD models has wide applicability in model consistency check and retrieval. In process plant, engineering design standards make 2D engineering drawing and 3D model differ in geometry, proportion and structure, leading to the inapplicability of current shape-feature based matching approaches. Since connection relationships between components are the core of a process plant, a topology based algorithm is proposed. Firstly, by exploiting components as vertices and relationships as edges, both 2D engineering drawing and 3D model are preprocessed into graph structures. Then each model’s relationship types are extracted from the graph. Finally, regarding the extracted relationship types as primary feature, feature similarity is calculated to measure the matching degree between their corresponding models. The proposed algorithm is geometric deformation invariant. Experiments with industrial applications are presented, which demonstrates the effectiveness and feasibility of the proposed algorithm.     

Graph cut based panoramic 3D modeling and ground truth comparison with a mobile platform – The Wägele

Efficient and comfortable acquisition of large 3D scenes is an important topic for many current and future applications in the field of robotics, factory and office visualization, 3DTV and cultural heritage.In this paper we present both an omnidirectional stereo vision approach for 3D modeling based on graph cut techniques and also a new mobile 3D model acquisition platform where it is employed. The platform comprises a panoramic camera and a 2D laser range scanner for self localization by scan matching. 3D models are acquired just by moving the platform around and recording images in regular intervals. Additionally, we concurrently build 3D models using two supplementary laser range scanners. This enables the investigation of the stereo algorithm’s quality by comparing it with the laser scanner based 3D model as ground truth. This offers a more objective point of view on the achieved 3D model quality.     

黄瓜生长可视化系统的设计与实现

利用计算机更好地模拟植物的生理过程、形态结构及生态变化的关键是确定虚拟植物模型。文中采用双尺度自动机模型模拟植物生长,对作物器官进行三维几何建模,以黄瓜为例设计并实现了作物生长可视化系统。该系统易于交互、真实感强、计算速度快并具有可扩展性,可以较好地模拟显示黄瓜整体植株与群体植株、群体漫游及黄瓜植株和黄瓜器官三维动态生长过程等。     

玉米可视化系统的设计与开发

计算机能更好地模拟玉米的生理过程、形态结构及生态变化的关键是确定玉米的虚拟模型和可视化实现技术。文中利用玉米的三维形态几何模型,采用面向对象的方法,对玉米各器官作为单独的对象进行处理,采用模型-文档-视图方法,设计实现了玉米三维可视系统。该系统对玉米的根、茎、叶、穗分别建立了动静态模型,可实现玉米各器官、单株和群体三维静态建模及动态生长过程。本方法具有普遍性,可用于开发其他禾谷类作物的三维造型和可视化系统。     

基于植物间互利作用的森林生长模型快速计算

植物间互利作用的研究与探索有助于加强林业生产中的混交林建设,从而提高林分生产力。为了快速地模拟植物间互利作用下的生长情况,提出了一种利用植物间互利生长模型进行森林场景快速可视化的方法。该方法通过植物间互利指数、植物自身的生长率、植物当前生物量、环境条件等参数将Lotka-Volterra种间互利模型与植物个体生长模型进行融合,并采用像素化方法进行快速计算,以模拟互利植物的生长情况。通过水曲柳和落叶松混交林在不同的环境资源条件、分布密度、生长时间等条件下的可视化仿真,验证了基于植物间互利作用的森林生长模型快速计算方法的有效性和实用性。     

CAD模型转换到VR模型的实时可视性研究

实时3D可视化是机械产品设计当中的一个主要问题,针对CAD几何学和装配以及机械产品的高可视化提出了MEMPHIS中间件框架,目的是连接实时虚拟现实应用,特别是CAD模型的管理操作设计。同时还保证了当进行模型转换时,在CAD模型上必须作相应的几何改变,系统会同步变化,这样避免了传统的从CAD模型转换到VR模型转换时人工加入虚拟现实特殊信息,如光照设置、材质、纹理、行为这些刻画VR模型可视化特性的信息属性后才能实现这种转换。从而大大提高了机械产品协同设计的效率和可视性性能。     

Visualization of structured nonuniform grids

Operational forecasters and weather researchers need accurate visualization of atmospheric data from both computational models and observed data. Although these two applications share some requirements, they have different needs and goals. We've developed a visualization tool for atmospheric science researchers and research weather forecasters that allows the 3D visualization of measured radar data and rendered numerical model data to show the 3D structures as well as how the weather event would look when observed in the field. Our system lets us load the original data directly onto the graphics hardware, with the grid mapping from the rendering space to the grid space programmed on the GPU. This method is flexible enough to handle the grids important in meteorological research and enables the application of advanced visualization methods available in texture-based slicing systems. The visually accurate rendering of weather data can be useful for training weather spotters, evaluating forecasting models, training forecasters to interpret radar data, and comparing sensor data to observed weather events.     

Web-based three-dimensional geo-referenced visualization

This paper addresses several approaches to implementing web-based, three-dimensional (3-D), geo-referenced visualization. The discussion focuses on the relationship between multi-dimensional data sets and applications, as well as the thick/thin client and heavy/light server structure. Two models of data sets are addressed in this paper. One is the use of traditional 3-D data format such as 3-D Studio Max, Open Inventor 2.0, Vis5D and OBJ. The other is modelled by a web-based language such as VRML. Also, traditional languages such as C and C++, as well as web-based programming tools such as Java, Java3D and ActiveX, can be used for developing applications. The strengths and weaknesses of each approach are elaborated. Four practical solutions for using VRML and Java, Java and Java3D, VRML and ActiveX and Java wrapper classes (Java and C/C++), to develop applications are presented for web-based, real-time interactive and explorative visualization.     

Visualization and 3D data processing in the David restoration

The program of scientific investigations planned in the framework of the restoration of Michelangelo's David produced several useful guidelines for defining and developing innovative ways to process and visualize 3D data in cultural heritage applications. Our ultimate goal was to include 3D graphics among the tools which can help restorers select the proper restoration procedures for the task at hand and objectively assess restoration results. For this, the David restoration was an ideal test bed to demonstrate the usefulness of digital 3D models and visualization tools in a restoration project. Because a complex set of scientific investigations was planned before and after the restoration intervention, we could try various methodologies to support restorers and scientists with visualization tools based on 3D digital models.