Application Of Curve Fitting In Irregular Block Surveying

The key content of the surveying and mapping projects such as land attribute determination and land surveys are the acquisition of spatial information for lands,which includes spatial position,shape,and its size etc.At present,there are two methods for the obtain of spatial information for lands:the field survey as well as internal image interpretation.However,no matter which approach you choose,the precision of survey and plotting no only depends on the accuracy of measurement points,but also the number and density of boundary points in the determination of land position,shape,and its proportion.Generally speaking,the higher the density of the boundary points,the higher the precision is,while the workload and amount of data also increase,triggering the decrease of working efficiency.Meanwhile,it also leads the increasing difficulty of subsequent data storage and maintenance.Furthermore,due to the expression pattern of polygons for traditional lands,the shape and position of irregular lands are not accurate,which causes larger error in the area calculation.For that reason,the curve fitting method is proposed to apply into the survey of irregular lands,which makes the spatial information more complete and real.In this paper,the internal interpretation of multiple irregular lands was conducted by means of three NURBS curve fitting and traditional survey methods,and comparison and analysis were also displayed.Results indicated that the curve fitting approach is capable to more accurate represent the spatial and position features of irregular blocks,and the accuracy of calculation of blocks is further improved.At the same time,it also,to large extents,reduces the number of boundary points.Furthermore,the spatial shape of irregular blocks and the distribution characteristics of boundary points are summarized comprehensively,the principle and methods corresponding to the.boundary points selection for irregular blocks with curve fitting method are put forward.Numerous experiments related block determination testify the feasibility of the proposed method,which serves the reference for the selection of control points in field survey.The field survey requires only a small number of optimal control points to obtain the information of the land through the curve-fitting mapping method,thereby improving the accuracy and efficiency of field measurement.