Adjustment Method Based On Surface Features Geometric Relations System

With the development and progress of computer technology, information science and mapping, digital topographic maps are more widely used in automatic mapping, urban planning, construction, geographic database building, land and cadastral management of information technology and related industries management. However, because of measurement error leading to the contours of same surface features in digital topographic maps or different objects may exist parallel, vertical, right circular tangent of lines, concentric circles, round and other conditions that could not be strictly right, which bring a lot of trouble to the planning and design, construction and other work.To solve this problem, this paper outlines characteristics of surface features for the observation point coordinates, a geometry based on surface features of the adjustment model, and develops the system to achieve the adjustment using C# language in Visual studio 2010 platform. The system adjustment results show that the adjustment methods described in this article is correct and feasible. Specific work and results are as follows:(1) Study geometry based on surface features of the adjustment model methods. Contour analysis of surface features geometric relationship between the common conditions using the theory of distinguishing geometric relationship between the plane vectors to model the adjustment. Condition equations are derived in parallel, vertical equations, boundary conditions equation looks to establish the process and the corresponding conditions for the existence of the threshold calculated by comparing the appropriate conditions for the size difference between the threshold and closed to determine the appropriate geometry conditions existence.(2) Study the automatic search algorithm of various geometrical relationship conditions. The algorithm is able to search all possible and independent conditions between the contour lines of Surface features to form the condition equations for the adjustment and to lay the foundation for the realization of the adjustment system.(3) Study the solution method of the adjustment model. In many cases the condition number of the condition equations for large sparse linear equations, the classical method to overcome the traditional equation solving speed and stability of the shortcomings, QR decomposition method is proposed for solving the model adjustment and using a sparse matrix approach, this method has the following advantages: saving memory, a direct solver, calculate speed, not on the matrix inverse operation, to a certain extent, solve the storage space and speed stability issues.(4)Develop a system to achieve adjustment based on geometry of surface features. QR decomposition method implemented, but also through the conditions to the conditions of the search group equations into a number of conditions for independent groups, each group independently solving the conditions to achieve the adjustment of the parallel processing, which takes full advantage of multi-core processing computer device computing power to improve relations based on geometric surface features adjustment system processing efficiency.(5) The method of the adjustment based on the geometric relationship between surface features resolves the problem that the possible geometric relationship conditions of surface features are not strictly true caused by measurement error. On the one hand through the adjustment of the calculated surface features characteristic point coordinate error 0.011m,surface features reflects the point of mathematical precision; the other hand the feather point coordinates of the surface features between the contour lines to meet the conditions of the geometric relationship may be, to some extent, improved the accuracy of digital topographic map.