一种基于对象存储的文件系统的设计

随着存储技术的飞速发展,对象存储设备面临如何高效存储并管理TB级容量数据的问题.针对Linux通用文件系统Ext2在处理大文件和巨型目录结构时存在的局限性,采用B 树结构设计并实现了一种基于连续块的对象文件系统.对该文件系统进行的测试结果表明,该文件系统的读写效率较高,而且随着文件的增大,性能保持稳定.     

Classification of the wildland–urban interface: A comparison of pixel- and object-based classifications using high-resolution aerial photography

The expansion of urban development into wildland areas can have significant consequences, including an increase in the risk of structural damage from wildfire. Land-use and land-cover maps can assist decision-makers in targeting and prioritizing risk mitigation activities, and remote sensing techniques provide effective and efficient methods to create such maps. However, some image processing approaches may be more appropriate than others in distinguishing land-use and land-cover categories, particularly when classifying high spatial resolution imagery for urbanizing environments. Here we explore the accuracy of pixel-based and object-based classification methods used for mapping in the wildland–urban interface (WUI) with free, readily available, high spatial resolution urban imagery, which is available in many places to municipal and local fire management agencies. Results indicate that an object-based classification approach provides a higher accuracy than a pixel-based classification approach when distinguishing between the selected land-use and land-cover categories. For example, an object-based approach resulted in a 41.73% greater accuracy for the built area category, which is of particular importance to WUI wildfire mitigation.     

智能存储及管理技术探析*

为了实现高性能、低成本管理和适应信息爆炸性增长的需求,存储系统应向存储智能化、管理自动化、存储容量无限方向发展。介绍了目前智能     

Multitemporal censusing of a population of eastern hemlock (Tsuga canadensis L.) from remotely sensed imagery using an automated segmentation and reconciliation procedure

Large-scale (1:3000) color aerial images of a population of eastern hemlock (Tsuga canadensis L.) were collected in the early spring of 1997, 1998, and 1999. An automated spatial segmentation procedure was developed to identify and measure individual population objects or blobs within the forest population. To ensure the comparability of multiyear segmentation maps, an automated blob reconciliation procedure was also developed to make certain that no hemlock pixels were assigned to different blobs in different years. The automated segmentation and reconciliation procedures were applied to a population of naturally occurring hemlock. Following spatial segmentation, a large majority of hemlock blobs (∼66-71%) were found to be closely associated with ground referenced, manually delineated individual hemlock crowns. The remaining blobs consisted of spatially distinct parts of a crown or closely clumped multiple crowns. Similar overall classification accuracies (∼63-72%) were found following the reconciliation of multitemporal image pairs. The development of these spatially explicit multitemporal population data sets should prove useful to further investigations of the dynamics of and environmental influence on plant populations.     

A layered coding system for very low bit rate video coding

Known coding techniques for transmitting moving images at very low bit rates are explained by the source models on which these coding techniques are based. It is shown that with motion-compensated hybrid coding, object-based analysis-synthesis coding, knowledge-based coding and semantic coding, there is a consistent development of source models. In consequence these coding techniques can be combined in a layered coding system. From experimental results obtained for object-based analysis-synthesis, coding estimates for the coding efficiency of such a layered coding system are derived using head and shoulder video telephone test sequences. It is shown that an additional compression factor of about 3 can be expected with such a complex layered coding system, when compared to block-based hybrid coding.     

Object-based visual attention for computer vision

In this paper, a novel model of object-based visual attention extending Duncan's Integrated Competition Hypothesis [Phil. Trans. R. Soc. London B 353 (1998) 1307-1317] is presented. In contrast to the attention mechanisms used in most previous machine vision systems which drive attention based on the spatial location hypothesis, the mechanisms which direct visual attention in our system are object-driven as well as feature-driven. The competition to gain visual attention occurs not only within an object but also between objects. For this purpose, two new mechanisms in the proposed model are described and analyzed in detail. The first mechanism computes the visual salience of objects and groupings; the second one implements the hierarchical selectivity of attentional shifts. The results of the new approach on synthetic and natural images are reported.     

深水水道形态定量分析及沉积模拟——以西非Gengibre油田为例

由于深水水道油藏多位于深海区,受作业成本限制,其开发井距往往较大,难以通过密井网多井拟合获取沉积定量关系.为此,利用西非Gengibre油田深水区浅层沉积高频地震资料,对陆坡区深水水道沉积特征和定量关系进行了研究,并指导深层稀井网油田水道储层模拟,提出了基于沉积定量分析的深水水道模拟思路.研究结果表明:单一水道呈整体迁移方式,迁移模式包含"侧向迁移"和"沿古流向迁移"2种类 型,定量沉积分析结果认为单一水道的宽度与深度之间存在较好的正相关性;浅层高频地震资料弥补了深层地震分辨率不足的缺陷,稀井网下深水水道模拟选用基于目标方法更为合适,模拟结果符合地质认识;将沉积定量认识整合到沉积相建模中,拓宽了相建模的思路,具有推广价值.研究成果不仅可以完善深水水道定量分布模式,而且对于高效开发深水水道油藏具有实用价值.     

Extraction of major object features using VQ clustering for content-based image retrieval

An image representation method using vector quantization (VQ) on color and texture is proposed in this paper. The proposed method is also used to retrieve similar images from database systems. The basic idea is a transformation from the raw pixel data to a small set of image regions, which are coherent in color and texture space. A scheme is provided for object-based image retrieval. Features for image retrieval are the three color features (hue, saturation, and value) from the HSV color model and five textural features (ASM, contrast, correlation, variance, and entropy) from the gray-level co-occurrence matrices. Once the features are extracted from an image, eight-dimensional feature vectors represent each pixel in the image. The VQ algorithm is used to rapidly cluster those feature vectors into groups. A representative feature table based on the dominant groups is obtained and used to retrieve similar images according to the object within the image. This method can retrieve similar images even in cases where objects are translated, scaled, and rotated.     

MPEG-4码率分配策略的局部优化

针对Vetro的MPEG4视频对象码率分配策略不足，提出了一种基于视觉的改进的码率分配策略，在低码率条件下允许为前景对象分配相对更多的码率。实验证明，此方法算法上易于实现，并取得了较好的优化效果。     

对象模型在集成电路掩膜光学临近矫正中的应用

随着超大规模集成电路的发展，其特征尺寸已经接近或小于掩膜光刻工艺中所使用的光波长。由于光的衍射和干涉现象，实际得到的光刻图形与掩膜图形之间存在一定的误差。为尽量消除这种误差，常用的两种方法是OPC和PSM。提出一种基于对象模型的OPC方法以及由此而开发的可实际应用的工具软件OPCM。该方法也为基于规则的OPC提供了产生基本规则的引擎，并由此而提高了软件的实用性。