A Collaborative Simplification Method for Multiple Coastlines Based on the Hierarchical Triangulation Network Partition

For the current automatic coastline generalization method,only one-line element is considered separately,but the relationship between the nearby elements is not effectively considered.A synergistic simplification method for multiple coastlines based on the hierarchical triangulation network partition(HTNP)is proposed in this paper.Firstly,the constrained Delaunay triangulation is constructed to partition the regions that can be simplified.Then,a hierarchical binary tree model to structure the morphological characteristics of the above several coastlines and the spatial proximity between different coastlines is constructed.Finally,the small curved and curved invisible parts of the coastline are deleted according to the visual constraints,and the narrow part between the coastline itself or the different coastlines is exaggerated appropriately,and the automatic simplification of the coastline is realized.The experimental results show that:①Relationships between the different coastlines are considered,and the shortcomings of considering the coastline separately are overcome;②Under the condition of the multiple coastlines in complex sea areas,the problem of collaborative simplification is solved,the quality of the coastlines are improved obviously,and the proposed method can be applied into more types of coastlines.

A block-based selection method for road network generalization

When road symbols are shown in a size proportionate to the reduced scale,several problems of legibility may arise concerning the urban blocks.By the method proposed in this paper,in order to overcome these problems,urban block areas are enlarged through amalgamation and the intervening roads in the amalgams are eliminated.This method includes two new approaches for computation of threshold used in determination of important roads based on the connectivity measure,and for definition of minimum block space and area requirements based on graphic limits.A block life cycle was designed for amalgamation of blocks.For the amalgamation process,a new algorithm was developed.The experimental testing indicates that important roads and the roads surrounding the urban area have been preserved.A simpler and more legible road network has been acquired.This method can be described as a more holistic approach as the buildings are taken into account.The problems arising in the experimental testing indicate that the cartographic selection/elimination process is not sufficient by itself for road network generalization,which can be assumed as one of the integral parts of Digital Earth.As well as the selection/elimination,processes such as displacement and caricaturizing are also needed.