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1.
文章介绍了一种基于压缩Voxel模型的五坐标数控加工仿真新方法。该方法采用压缩Voxel模型表示数控加工工件模型和刀具空间扫描体模型,计算机内部存贮空间小,布尔操作简单、速度快。通过MarchingCubes方法提取数控加工仿真工件表面三角网格模型并进行图形显,提高了仿真工件显示质量。文章同时提出了一种基于压缩Voxel模型的刀具空间扫描体构造新方法,通过构造基本几何体球体、圆柱体、圆环体、锥形体和鼓形体的空间扫描体,完成各种加工刀具棒刀、球头刀、环形刀、锥形刀和鼓形刀空间扫描体压缩Voxel模型。该方法在《基于压缩Voxel模型的五坐标数控加工仿真系统》中得到了应用,仿真结果三维信息完备,操作人员可从任意方向观察、验证仿真结果,克服了现有五坐标数控加工仿真方法和商品化软件系统的不足,该方法是虚拟数控加工的关键技术。  相似文献   

2.
XML即可扩展标记语言,是为了在网络中说明和交换数据而制定的标准数据格式,而作为数据载体的XML文档的体积也随着交换数据增多而变得越来越大,这给网络上的数据传输造成了很大的负担.为此,先把数据库里的数据生成XML,再加工成压缩包,就是每一条数据都是xml.zip的压缩包,利用C#编写定时程序进行定时压缩,不用手动,最后用于数据推送.  相似文献   

3.
压缩域多媒体数据处理技术研究   总被引:5,自引:0,他引:5       下载免费PDF全文
多媒体数据压缩技术是多媒体、网络通讯以及计算机等应用领域的一项关键技术。多媒体数据经过压缩后再进行存储或通过网络进行传输,这已经逐渐成为多媒体应用中的标准模式;同时,多媒体应用中所涉及到的各种媒体数据,如图象、视频和音频数据,往往需要进行各种灵活的操作与处理,因此,压缩域多媒体数据直接处理技术成为一项很有意义的研究领域。文中首先就压缩数据处理的基本概念进行讨论,然后集中分析了这一研究领域的重要研究  相似文献   

4.
The field of wavelets has opened up new opportunities for the compression of satellite data. This paper examines the influence of data compression on the automatic classification of urban environments. Data from Daedalus airborne scanner imagery is used. Laser scanning altitude data is introduced as an additional channel alongside the spectral channels thus effectively integrating the local height and multispectral information sources. In order to incorporate context information, the feature base is expanded to include both spectral and non-spectral features. A maximum likelihood classification is then applied. It is demonstrated that the classification of urban scenes is considerably improved by fusing multispectral and geometric data sets. The fused imagery is then systematically compressed (channel by channel) at compression rates ranging from 5 to 100 using a wavelet-based compression algorithm. The compressed imagery is then classified using the approach described hereabove. Analysis of the results obtained indicates that a compression rate of up to 20 can conveniently be employed without adversely affecting the segmentation results.  相似文献   

5.
随着数据采集尤其是3维激光扫描技术的发展,对地物目标建立的表面模型越来越精细,由于其不仅导致数据存储量急剧增大,也降低了图形实时交互显示的速度,因此必须对表面模型数据进行压缩处理。为了对原始扫描构模表面模型进行合理、有效的压缩处理,在Garland提出的表面模型压缩算法的基础上,提出了一种新的基于边收缩的表面模型数据压缩算法。该算法首先依据二次误差度量准则计算边收缩的代价,同时确定各边收缩的顺序,然后利用半空间测试方法判断边收缩的合法性,以实现表面模型的边界区域与内部区域的同步压缩。实践表明,该算法不仅在高压缩比的情况下仍能保留原始模型的几何特征,而且能有效地保证压缩模型的质量。  相似文献   

6.
Recently, remote monitoring camera systems have been widely used for security. In such systems, one important function is that the system automatically detects any change in the scenes from the monitoring cameras. In wireless remote monitoring camera systems, the images of the scenes are generally transmitted as compressed data (e.g., JPEG file), because of the capacity of the wireless channel. This article shows the automated detection of the change point in time-series data of compressed JPEG file quantity (Kbytes) from the monitoring camera by applying the sequential probabilistic ratio test (SPRT) and the Chow test, which is well known as a standard method for detecting structural change in time-series data.  相似文献   

7.
Coherent multiresolution isosurface ray tracing   总被引:1,自引:0,他引:1  
We implement and evaluate a fast ray tracing method for rendering large structured volumes. Input data is losslessly compressed into an octree, enabling residency in CPU main memory. We cast packets of coherent rays through a min/max acceleration structure within the octree, employing a slice-based technique to amortize the higher cost of compressed data access. By employing a multiresolution level of detail (LOD) scheme in conjunction with packets, coherent ray tracing can efficiently render inherently incoherent scenes of complex data. We achieve higher performance with lesser footprint than previous isosurface ray tracers, and deliver large frame buffers, smooth gradient normals and shadows at relatively lesser cost. In this context, we weigh the strengths of coherent ray tracing against those of the conventional single-ray approach, and present a system that visualizes large volumes at full data resolution on commodity computers.  相似文献   

8.
Complex repetitive scenes containing forests, foliage, grass, hair, or fur, are challenging for common modeling and rendering tools. The amount of data, the tediousness of modeling and animation tasks, and the cost of realistic rendering have caused such kind of scene to see only limited use even in high-end productions. The author describes how the use of volumetric textures is well suited to such scenes. These primitives can greatly simplify modeling and animation tasks. More importantly, they can be very efficiently rendered using ray tracing with few aliasing artifacts. The main idea, initially introduced by Kajiya and Kay (1989), is to represent a pattern of 3D geometry in a reference volume, that is tiled over an underlying surface much like a regular 2D texture. In our contribution, the mapping is independent of the mesh subdivision, the pattern can contain any kind of shape, and it is prefiltered at different scales as for MIP-mapping. Although the model encoding is volumetric, the rendering method differs greatly from traditional volume rendering. A volumetric texture only exists in the neighborhood of a surface, and the repeated instances (called texels) of the reference volume are spatially deformed. Furthermore, each voxel of the reference volume contains a key feature which controls the reflectance function that represents aggregate intravoxel geometry. This allows for ray tracing of highly complex scenes with very few aliasing artifacts, using a single ray per pixel (for the part of the scene using the volumetric texture representation). The major technical considerations of our method lie in the ray-path determination and in the specification of the reflectance function  相似文献   

9.
三维激光扫描数据的压缩与地形采样   总被引:8,自引:1,他引:8  
刘春  陆春 《遥感信息》2005,(2):6-10
三维激光扫描测量具有速度快、效率高、实时性强等特点,由于其数据量特别大,数据特别精细,在存储和运算上受到的限制比较大。针对上述问题本文讨论了三维激光扫描数据的压缩和滤波,针对地形采集的需要,探讨了在三维激光扫描数据上获取地形采样点的具体方法。同时实例针对三维激光扫描数据点距小的特点对原有数据进行按序抽点,通过计算回光强度熵的信息对压缩效果进行检验,并用压缩后的数据生成等高线。  相似文献   

10.
针对利用最小包围盒(MBB)压缩的移动物体时空轨迹,为了能对其进行有效地聚类,提出了一个基于盒内数据点密度的轨迹间相似性度量公式.首先,把两条轨迹的相似性度量转化为两条轨迹上有时间交叠的MBB之间的相似性度量,这在很大程度上减少了数据存储量.其次,分析两条轨迹上有时间交叠的MBB之间影响相似性的因素:时间持续、空间距离和盒内数据点的密度.剖析这3个因素对轨迹相似性的影响作用,提出了利用MBB压缩的移动物体时空轨迹相似性度量公式.实验证明采用本公式对移动物体时空轨迹进行聚类,可以提高聚类结果有效性指标Dunn的值.  相似文献   

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