基于MAPGIS的图元列表查询技术及其实现

图元重叠和压盖是GIS数据中经常遇到的现象,针对MAPGIS 6.x平台系统所提供的查询方式由于频繁地逐个图元提问,而不能满足用户快速查询的需要。这里首次提出了图元列表查询技术来解决叠盖图元的查询问题,并给出了它的实现流程,讨论了关键实现技巧。图元列表查询不仅可在列表中直观地列出用户指定位置处所有叠盖图元的基本信息,还可进一步详细查询各个图元的信息(属性信息、图形参数信息),查询快速、操作简便。最后用实例证明了该技术的实用性。

MAPGIS-based query technology of listing elements and its implementation

It is a common phenomenon that one element is overlapped another in one layer or in a project during GIS data processing.The problem is that current query technique provided by MAPGIS 6.x can not satisfy user's needs to query the elements quickly because system requires user to answer questions endlessly.This paper brings forward a new query technique of listing elements to solve this problem.The implementation flow chart of this technique is shown and some key skills are explained in detail.Through this query technique,all basic information of items related to the spatial locations required by user can be listed intuitionally.Furthermore,the information on each element,such as attributes or graphic parameters,etc.,can be displayed in detail.The process can be realized quickly by simple operation.A case study to query the elements from the spatial database of geological survey extent during 20th century in China illustrates the effectiveness of this technique.