[Retracted] 3D City Online Visualization and Cluster Architecture for Digital City

Table 1

Comparison of three digital elevation models.

Structure	Regular grid	Contour line	Irregular triangulation
Data size	View grid size	Small	Big
Generation method	Data interpolation	Remote sensing topographic map	Discrete point networking
Topological relationship	Good	No good	Good
Arbitrary point interpolation	Direct	Indirect	Direct
Suitable for terrain	Gentle but not severe	Gentle but not severe	Arbitrary terrain