基于VTK的医学图像三维重建应用研究

医学体数据可视化在临床上已成为辅助诊断和辅助治疗的重要手段,其技术也成为近年来研究和应用的热点.为此,我们提出采用VTK库进行医学数据可视化.其中研究了表面绘制和体绘制两种绘制技术,表面绘制用移动立方体法实现,体绘制则用光线投射法实现,并通过比较两种技术的结果讨论了他们的特点.从结果中可以看出,VTK作为一种图像处理和三维可视化的工具其功能是十分强大的.     

医学体数据三维重建体绘制技术研究

在分析医学体数据三维重建基本过程的基础上,介绍了光线投射法、足迹法、错切-变形法和基于小波变换的体绘制等典型算法,讨论了各类算法的优缺点以及改进方向,并展望了医学体数据体绘制技术的未来研究方向。     

Cinematic Rendering in Anatomy: A Crossover Study Comparing a Novel 3D Reconstruction Technique to Conventional Computed Tomography

Integration of medical imaging into preclinical anatomy courses is already underway in many medical schools. However, interpretation of two-dimensional grayscale images is difficult and conventional volume rendering techniques provide only images of limited quality. In this regard, a more photorealistic visualization provided by Cinematic Rendering (CR) may be more suitable for anatomical education. A randomized, two-period crossover study was conducted from July to December 2018, at the University Hospital of Erlangen, Germany to compare CR and conventional computed tomography (CT) imaging for speed and comprehension of anatomy. Sixteen students were randomized into two assessment sequences. During each assessment period, participants had to answer 15 anatomy-related questions that were divided into three categories: parenchymal, musculoskeletal, and vascular anatomy. After a washout period of 14 days, assessments were crossed over to the respective second reconstruction technique. The mean interperiod differences for the time to answer differed significantly between the CR–CT sequence (−204.21 ± 156.0 seconds) and the CT–CR sequence (243.33 ± 113.83 seconds; P < 0.001). Overall time reduction by CR was 65.56%. Cinematic Rendering visualization of musculoskeletal and vascular anatomy was higher rated compared to CT visualization (P < 0.001 and P = 0.003), whereas CT visualization of parenchymal anatomy received a higher scoring than CR visualization (P < 0.001). No carryover effects were observed. A questionnaire revealed that students consider CR to be beneficial for medical education. These results suggest that CR has a potential to enhance knowledge acquisition and transfer from medical imaging data in medical education.     

序列二维医学图象的体绘制法

Volume rendering of 3D data sets composed of sequential 2D medical images has become an important branch in image processing and computer graphics.To help physicians fully understand deep-seated human organs and focuses(e.g.a tumour)as 3D structures.in this paper,we present a modified volume rendering algorithm to render volumetric data,Using this method.the projection images of structures of interest from different viewing directions can be obtained satisfactorily.By rotating the light source and the observer eyepoint,this method avoids rotates the whole volumetric data in main memory and thus reduces computational complexity and rendering time.Experiments on CT images suggest that the proposed method is useful and efficient for rendering 3D data sets.     

基于区域空间的LH直方图传递函数水声数据算法

体数据边界信息直接决定可视化效果,而传递函数设计是实现可视化的关键。虽然基于LH直方图的传递函数能够显著提高边界区分能力,但现有方法由于LH值计算效率低,无法满足实时交互需求。因此,提出一种基于区域空间的LH直方图传递函数方法,可限定直方图计算空间,与现有基于阈值的LH传递函数方法相比,节省了近50%的计算耗费时间,同时能够实现较好的绘制效果。     

输变电GIS系统中电力线路要素模型库的建立

在输变电GIS三维可视化过程中,建立电力线路要素三维模型库是非常重要的。本文给出了建立三维模型库的方法。使用3DMAX作为建模工具,并用OSG做为底层的渲染基础框架设计了8种电力线路模型原型,提出了动态模型实列的概念和分页加载渲染的方法,制定了数据存储格式与标准,使得GIS系统能够直接从模型库中调用线路杆塔模型,实现了输电线路的三维全景仿真。     

A Visualization System for Correctness Proofs of Graph Algorithms

In this paper we describe a system for visualizing correctness proofs of graph algorithms. The system has been demonstrated for a greedy algorithm, Prim's algorithm for finding a minimum spanning tree of an undirected, weighted graph. We believe that our system is particularly appropriate for greedy algorithms, though much of what we discuss can guide visualization of proofs in other contexts. While an example is not a proof, our system provides concrete examples to illustrate the operation of the algorithm. These examples can be referred to by the user interactively and alternatively with the visualization of the proof where the general case is portrayed abstractly.     

基于ITK和VTK的三维成像实现

介绍了Fast Marching快速行进图像分割和Marching Cubes步进立方体2种算法的原理,利用ITK的图像读取与处理功能及VTK在可视化方面的突出能力,将二者有机地集成起来,通过ITK和VTK实现这2种算法,最终生成三维立体医学图像。实验结果验证了该方法可以得到病理部位的详细特征,在医学图像三维成像方面有良好的性能。     

分割技术的改进及在医学体视化中的应用

为了提高医学诊断和手术的准确性和科学性,需要设计一套基于微机平台、价格低廉且使用方便的医学体视化软件。在此以Visual C++6.0为开发工具,通过图像分割的几种不同算法的改进、设计与实现,对所产生的结果进行对比分析,得出结论,医学体数据的分割虽然还没有一个特定的标准,但对不同的医学体数据,不同的医学体数据类型,可以寻找一种较好的分割算法进行分割。     

Interactive learning system “VisMis” for scientific visualization course

Now visualization courses have been taught at universities around the world. Keeping students motivated and actively engaged in this course can be a challenging task. In this paper we introduce our developed interactive learning system called VisMis (Visualization and Multi-modal Interaction System) for postgraduate scientific visualization course at Beijing Normal University. We develop it following the Great Didactic from Comenius and the theory of constructivism on constructing the visual and interactive learning environment to support and challenge the student’s learning. We give a report on our proprietary system including its educational objective, volume visualization module, multi-modal interaction module, and CUDA implementation etc. By the evaluation, we conclude that VisMis is an innovative platform for volume visualization with novel transfer function design and multi-modal interaction. It has more advantage in easiness, speed, layer control, interaction, etc.     

Dynamic Distribution Model with Prime Granularity for Parallel Computing

Dynamic distribution model is one of the best schemes for parallel volume rendering. However, in homogeneous cluster system, since the granularity is traditionally identical, all processors communicate almost simultaneously and computation load may lose balance. Due to problems above, a dynamic distribution model with prime granularity for parallel computing is presented. Granularities of each processor are relatively prime, and related theories are introduced, A high parallel performance can be achieved by minimizing network competition and using a load balancing strategy that ensures all processors finish almost simultaneously, Based on Master-Slave-Gleaner （ MSG） scheme, the parallel Splatting Algorithm for volume rendering is used to test the model on IBM Cluster 1350 system. The experimental results show that the model can bring a considerable improvement in performance, including computation efficiency, total execution time, speed, and load balancing.     

基于CT、MRI断层图像的人体三维建模

人体三维几何建模及其可视化显示是生物医学学科的一项基础性研究。CT和MRI等医学成像技术的断层图像可为三维建模提供基础。章论述和介绍了基于CT、MRI断层图像的三维建模系统的关键技术和相关实现原理。     

What goes before the CART? Introducing classification trees with Arbor and CODAP

This volume is largely about nontraditional data; this paper is about a nontraditional visualization: classification trees. Using trees with data will be new to many students, so rather than beginning with a computer algorithm that produces optimal trees, we suggest that students first construct their own trees, one node at a time, to explore how they work, and how well. This build-it-yourself process is more transparent than using algorithms such as CART; we believe it will help students not only understand the fundamentals of trees, but also better understand tree-building algorithms when they do encounter them. And because classification is an important task in machine learning, a good foundation in trees can prepare students to better understand that emerging and important field. We also describe a free online tool—Arbor—that students can use to do this, and note some implications for instruction.     

数据场体视化方法综述

数据场体视化使人们可以从一幅图象里感受到数据整体的信息．本文研究了大量体视化方面文献后,总结了体视化的研究方法,并提出了当前的研究热点及今后的研究方向．     

基于CUDA的三维数据场可视化加速技术研究

三维数据场可视化是目前计算机图形学方向研究的热点之一,随着人们需求的不断提高,对图形绘制的实时性及交互性提出了更高的要求。本文主要阐述了在CUDA架构下,利用GPU的多核并行运算能力,对实现三维数据场可视化的光线投射算法进行优化和改进。将图形处理的几何阶段在可编程硬件实现,实现图形绘制的加速。实验结果表明,在一定程度上改善了成像效果,绘制速度的加速比达到7左右。     

Visualization of stereoscopic anatomic models of the paranasal sinuses and cervical vertebrae from the surgical and procedural perspective

Recent improvements in three‐dimensional (3D) virtual modeling software allows anatomists to generate high‐resolution, visually appealing, colored, anatomical 3D models from computed tomography (CT) images. In this study, high‐resolution CT images of a cadaver were used to develop clinically relevant anatomic models including facial skull, nasal cavity, septum, turbinates, paranasal sinuses, optic nerve, pituitary gland, carotid artery, cervical vertebrae, atlanto‐axial joint, cervical spinal cord, cervical nerve root, and vertebral artery that can be used to teach clinical trainees (students, residents, and fellows) approaches for trans‐sphenoidal pituitary surgery and cervical spine injection procedure. Volume, surface rendering and a new rendering technique, semi‐auto‐combined, were applied in the study. These models enable visualization, manipulation, and interaction on a computer and can be presented in a stereoscopic 3D virtual environment, which makes users feel as if they are inside the model. Anat Sci Educ 10: 598–606. © 2017 American Association of Anatomists.     

基于OpenGL的纹理映射研究

介绍了纹理细节模拟方法。使用OpenGL的编程接口,应用纹理映射技术,实现场景中三维地形可视化。纹理映射技术的应用能增强三维场景绘制的真实感,并能提高三维场景的渲染速度。     

论立功的成立条件

立功是1997年修订刑法新规定的一种量刑制度,对其研究相对薄弱。正确认识立功的成立条件,是司法实践中正确认定立功,从而对有立功表现的犯罪分子准确量刑的前提。关于立功成立条件,各家观点不一,主要有二要件说、三要件说与四要件说。对立功条件的分析归纳要源于法律的规定,忠于法律的规定;作为一种量刑制度它必然要求具有较强的可操作性,所以对立功成立条件的重构要以便于司法操作为宗旨。据此,重构后的立功之成立条件应包括前提条件、时间条件、行为条件与有效性条件四个方面。前提条件是犯罪分子实施了犯罪行为;时间跨度界定为“从犯罪成立之后至判决、裁定生效前”的时间段;行为条件是犯罪分子实施了对国家和社会有益的行为;有效性是立功是否成立的关键性条件。没有必要将主观方面单列为立功的成立条件。重大立功与立功没有本质上的差异,只是程度上的不同,所以重构后的立功成立的四个条件之原理对重大立功同样适用。     

试析药品说明书的英文文体特征

药品说明书是一种科技应用文。本文对所收集的 10 0多份英文药品说明书进行详细整理和分析 ,并参阅了大量相关书籍和文章 ,从布局谋篇、词汇特色和句法特征等 3个方面对药品说明书的英文文体特征做出了初步探讨 ,目的在于掌握英文药品说明书的文体特点 ,从而促进药品说明书的正确理解和翻译     

基于自适应四叉树视相关多分辨率地形研究

地形实时绘制和交互式可视化是虚拟现实、地理信息系统、计算机图形学、科学计算可视化等技术的关键问题。本文对地表模型的实时生成和简化方法进行了研究和分析,提出了基于自适应四叉树视相关多分辨率地形生成方法。