Since web based GIS processes large size spatial geographic information on internet, we should try to improve the efficiency of spatial data query processing and transmission. This paper presents two efficient metho...Since web based GIS processes large size spatial geographic information on internet, we should try to improve the efficiency of spatial data query processing and transmission. This paper presents two efficient methods for this purpose: division transmission and progressive transmission methods. In division transmission method, a map can be divided into several parts, called “tiles”, and only tiles can be transmitted at the request of a client. In progressive transmission method, a map can be split into several phase views based on the significance of vertices, and a server produces a target object and then transmits it progressively when this spatial object is requested from a client. In order to achieve these methods, the algorithms, “tile division”, “priority order estimation” and the strategies for data transmission are proposed in this paper, respectively. Compared with such traditional methods as “map total transmission” and “layer transmission”, the web based GIS data transmission, proposed in this paper, is advantageous in the increase of the data transmission efficiency by a great margin.展开更多
随着Internet技术的快速发展,Web数据库数目庞大而且仍在快速增长。为有效组织利用深藏于Web数据库上的信息,需对其按领域进行分类和集成。Web页面上的查询接口是网络用户访问Web数据库的唯一途径,对Deep Web数据源分类可通过对查询接...随着Internet技术的快速发展,Web数据库数目庞大而且仍在快速增长。为有效组织利用深藏于Web数据库上的信息,需对其按领域进行分类和集成。Web页面上的查询接口是网络用户访问Web数据库的唯一途径,对Deep Web数据源分类可通过对查询接口分类实现。为此,提出一种基于查询接口文本VSM(Vector Space Model)的分类方法。首先,使用查询接口文本信息构建向量空间模型,然后通过典型的数据挖掘分类算法训练分类器,从而实现对查询接口所属领域进行分类。实验结果表明给出的方法具有良好的分类性能。展开更多
文摘Since web based GIS processes large size spatial geographic information on internet, we should try to improve the efficiency of spatial data query processing and transmission. This paper presents two efficient methods for this purpose: division transmission and progressive transmission methods. In division transmission method, a map can be divided into several parts, called “tiles”, and only tiles can be transmitted at the request of a client. In progressive transmission method, a map can be split into several phase views based on the significance of vertices, and a server produces a target object and then transmits it progressively when this spatial object is requested from a client. In order to achieve these methods, the algorithms, “tile division”, “priority order estimation” and the strategies for data transmission are proposed in this paper, respectively. Compared with such traditional methods as “map total transmission” and “layer transmission”, the web based GIS data transmission, proposed in this paper, is advantageous in the increase of the data transmission efficiency by a great margin.
文摘随着Internet技术的快速发展,Web数据库数目庞大而且仍在快速增长。为有效组织利用深藏于Web数据库上的信息,需对其按领域进行分类和集成。Web页面上的查询接口是网络用户访问Web数据库的唯一途径,对Deep Web数据源分类可通过对查询接口分类实现。为此,提出一种基于查询接口文本VSM(Vector Space Model)的分类方法。首先,使用查询接口文本信息构建向量空间模型,然后通过典型的数据挖掘分类算法训练分类器,从而实现对查询接口所属领域进行分类。实验结果表明给出的方法具有良好的分类性能。
