Оцінка методів ентропійного кодування зв’язності сіткової моделі

Кодування даних 3D об’єктів можна класифікувати різними шляхами. Якщо розглядувати зв’язність сіткової моделі таких об’єктів, алгоритми кодування можна розділити на 3 групи: 1) методи, в яких кодові символи пов’язані з площинами; 2) методи, в яких кодові символи пов’язані з вершинами; 3) методи, в яких кодові символи пов’язані з ребрами

Оцінка методів ентропійного кодування зв’язності сіткової моделі

Кодування даних 3D об’єктів можна класифікувати різними шляхами. Якщо розглядувати зв’язність сіткової моделі таких об’єктів, алгоритми кодування можна розділити на 3 групи: 1) методи, в яких кодові символи пов’язані з площинами; 2) методи, в яких кодові символи пов’язані з вершинами; 3) методи, в яких кодові символи пов’язані з ребрами

Triangle mesh compression and homological spanning forests

Triangle three-dimensional meshes have been widely used to represent 3D objects in several applications. These meshes are usually surfaces that require a huge amount of resources when they are stored, processed or transmitted. Therefore, many algorithms proposing an efficient compression of these meshes have been developed since the early 1990s. In this paper we propose a lossless method that compresses the connectivity of the mesh by using a valence-driven approach. Our algorithm introduces an improvement over the currently available valence-driven methods, being able to deal with triangular surfaces of arbitrary topology and encoding, at the same time, the topological information of the mesh by using Homological Spanning Forests. We plan to develop in the future (geo-topological) image analysis and processing algorithms, that directly work with the compressed data

A new method for simplification and compression of 3D meshes

We focus on the lossy compression of manifold triangle meshes. Our SwingWrapper approach partitions the surface of an original mesh M into simply-connected regions, called triangloids. We compute a new mesh M\u27. Each triangle of M\u27 is a close approximation of a pseudo-triangle of M. By construction, the connectivity of M\u27 is fairly regular and can be compressed to less than a bit per triangle using EdgeBreaker or one of the other recently developed schemes. The locations of the vertices of M\u27 are compactly encoded with our new prediction scheme, which uses a single correction parameter per vertex. For example, a variety of popular models retiled with our approach yield 10 times fewer triangles without exceeding an error of 1% of the radius of the bounding ball. Vertices of M\u27 are encoded with an average of 6 bits, which results in a total storage of 0.4 bits per triangle of the original mesh. The proposed solution may also be used to encode crude meshes for adaptive transmission and for controlling subdivision surfaces

Human Face Image Edge Detection Methods and Application

如何确定人脸特征并对这些特征进行有效的提取是非常关键而且复杂的。人脸边缘和轮廓是人脸非常重要的特征。该文研究了边缘检测的原理和各种算法,通过试验验证各种检测方法在人脸图像中对边缘的检测效果,讨论选用在不同阈值下检测的边缘,以及影响检测效果的因素。最后通过实例研究了人脸边缘检测在人脸检测和识别中的具体应用。How to define and extract the feature of human face is a key and complicated problem. The edge and contour of human face is one of important feature. This paper studies the theory of edge detection and different kinds of arithmetical methods. The experiment results are used to confirm the different methods which are employed to test the edge detection results of the human face image. It discusses the consequence of detection when the threshold is varying and the possible factors, which makes the different results. Finally, it studies the application of the edge detection in human face detection and recognition.福建省自然科学基金资助项目(A0310005);; 国家留学回国人员基金资助项目(K13003

From Capture to Display: A Survey on Volumetric Video

Volumetric video, which offers immersive viewing experiences, is gaining increasing prominence. With its six degrees of freedom, it provides viewers with greater immersion and interactivity compared to traditional videos. Despite their potential, volumetric video services poses significant challenges. This survey conducts a comprehensive review of the existing literature on volumetric video. We firstly provide a general framework of volumetric video services, followed by a discussion on prerequisites for volumetric video, encompassing representations, open datasets, and quality assessment metrics. Then we delve into the current methodologies for each stage of the volumetric video service pipeline, detailing capturing, compression, transmission, rendering, and display techniques. Lastly, we explore various applications enabled by this pioneering technology and we present an array of research challenges and opportunities in the domain of volumetric video services. This survey aspires to provide a holistic understanding of this burgeoning field and shed light on potential future research trajectories, aiming to bring the vision of volumetric video to fruition.Comment: Submitte

Mesh compression: Theory and practice.

Three-dimensional meshes (3D meshes, for short) are fast becoming an emerging media type, used in a variety of application domains such as engineering design, manufacture, architecture, bio-informatics, medicine, entertainment, commerce, science, defense, etc. The volume of data of this media type that is being circulated on the internet is increasing very rapidly and is being used as frequently as other media types like text, audio (1D), images and video (2D). Hence, 3D meshes need good processing and visualization methods. Also, the sizes of these meshes are much greater than the other media types mentioned above and often exceeds the memory and bandwidth available for their storage and transmission. Compression schemes for such large 3D meshes have become a subject of intense study lately. Meshes are either made up of triangles or quadrilaterals. Meshes made up of only triangles are called triangle meshes and meshes made up of quadrilaterals are called quadrilateral meshes (quad meshes, for short). A mesh is described by specifying its geometry (vertex coordinates) and its connectivity (adjacencies of the triangles or quadrilaterals). Previous research on mesh compression has been mostly for triangle meshes. Quad meshes were traditionally handled by first triangulating them and then applying triangle mesh compression techniques. In order to avoid this additional triangulation step, a direct technique is proposed for compressing and decompressing the connectivity of quad meshes. This technique takes a quad mesh as input and encodes its connectivity as a sequence of opcodes which can be restored back to the quad mesh, using the decompression technique. A data structure called EdgeTable is introduced to aid in the traversal of a quad mesh during compression. Also, a technique based on constrained Delaunay triangulation for reconstructing the connectivity of a 2D mesh from its geometry and a minimum set of edges is proposed. Source: Masters Abstracts International, Volume: 44-03, page: 1393. Thesis (M.Sc.)--University of Windsor (Canada), 2005