Gis Component Model Of Transportation Centerline

Based on research of geometric feature and mathematical model of transportation centerline, this paper investigates the component modeling and development technology of transportation centerline for GIS using object-oriented method.After research of geometric feature and component application characteristics of transportation centerline, a continuous description model and a discrete description model of centerline are presented. A natural parameters equation is used to descript the line segment, circle arc and transition curve of transportation centerline. A polyline approach is used to approximate the transition curve and a precise formula for determining segments number of the polyline is ratiocinated by numerical integral method.Using object-oriented data modeling method and Unified Modeling Language, the component model of transportation centerline is presented. Objects of component, relationship of the objects, attribute data and member function of the centerline component are all defined in detail. At last, mapping method from component's data model to relational database and the table structure of data are defined.The development technology of transportation centerline component is studied in detail. Using component-oriented programming technology, software architecture and interface of the component is defined, and an executable component is developed in.NET platform.Based on analysis. of working procedures of highway alignment design, the requirement, function and data store structure of Highway Alignment Computer Aided Design system, HACAD is defined. At last, a prototype software of HACAD is developed to validate the adaptability and feasibility of the component.