Multi-scale display of point data sets at the client side

Multi-scale representation of geographic features is one of the research focuses of Geographic Information System (GIS). Most of the work has been done at the server side, especially when dealing with massive lines and polygons data by using spatial database technology. This paper discusses the issue about multi-scale display of point data sets, and presents a solution which is implemented at the client side. This solution overcomes the problem of losing some points of interest and their attribute. It also promotes the efficiency of displaying large point dataset with limited pixels. First, we process the level of details at the client side to avoid communicating with the server side at every scale but only at the first process. This strategy greatly decreases the time consumption in querying the server and network transmission. Second, when doing multi-scale manipulations at the server side (including spatial database), some points at certain scales will lose; some points more or less at certain scales will be disposed. However, by processing at the client side, because it contains all of the point data sets, this problem is solved. At last, this paper designs an adaptive algorithm to resolve the contradiction between small screen area and large point data sets with the tedious overlap phenomenon in displaying. A case study verifies the optimized display effect and improved efficiency of the proposed approach.