Research On River System Traceability Algorithm And Structured Gradient Model

Based on a large amount of practical experience and basic knowledge of river systems,this paper proposes an automatic gradient method for river systems.This method realizes the automatic tracing the source of the river system and the structured gradient of the river system,and then forms a complete processing system of river system.And through summarizing the characteristics of different river systems,it was found that different types of river systems can be decomposed into several different dendritic river systems.This article studies the basic theory of the river system and concludes the structural characteristics of the river system.Therefore,this paper takes the dendritic river system as the main research object,and studies the structure and gradient method of the river system.Any research method must follow certain research criteria which are equivalent to the general direction of research methods,so do this article.Based on the related theories of the river system and the experience of a large number of cartography,this article summarizes nine specific rules and three general rules of the river system gradient,which are used as the guiding ideology of the automatic gradient algorithm for river systems.Based on the above theory,this paper proposes an automatic gradient algorithm for the river system,which uses the river system as a complete data structure for calculation.In this method,the disorganized river system data is processed into a river arc section to undergo unitized preprocessing.And then,the data is stored in the form of a directed graph,the direction of the river flow is the direction of the directed graph.According to the longest principle of the mainstream,reverse tracing the source of the river,and then storing the river system data as complete rivers.Second,this paper proposes a structural quantitative model of the river system to quantifying the river system according to the constraints of river length,topological relationship,and river integrity.Then make a gradient of the entire river system.According to the gradient requirements,this paper proposes a uniform linear gradient model and visual illusion gradient model.At the same time,according to the attributes of the river,it is divided into the gradient of the perennial river and the gradient of the seasonal river.In the end,in order to realize the fluency of the river,this paper uses the method of curve simplification to redistribute the characteristic points of the river,realize the comparison of the bending coefficients of different river sections,ensure the upper and lower river pattern characteristics,and obtain the final result of the river gradient in an ideal state.The gradient of the river system proposed in this paper has been removed from the subjective model that used to rely on human intervention to identify the mainstream,and achieved automatic traceability of rivers.In addition,the method gradates the whole river system as a whole,and combs the structure of the river system very well.And this method shows a clear and comprehensive visualization of the relationships between upstreams and downstreams and the relationship between mainstream and tributaries.At the same time,this article has improved the effect of river gradients,achieved fluency of lines,clarity of structure,and scientificity of gradation,providing reference and consultation for future research.