Data Processing And Projection Distortion Of GPS Control Network On Large-Scale Precision Engineering

With the rapid development of high-speed railway in China, the original control survey accuracy and data processing methods cannot meet the requirements of high-speed railway. In view of high precision features of large-scale engineering and in the establishment of large-scale transformation of the superiority of control network about GPS technology, the thesis works from the GPS control network adjustment, network projection deformation and the difference between the surface of engineering construction and engineering project .the thesis will have a detailed description and discussion from the flowing three aspects.First, this thesis starts with basic theories of the geodesy. it discusses GPS engineering net adjustment in the geocentric coordinate system, three-dimensional constrained adjustment in three-dimensional reference coordinate system, the two constrained adjustment on the Gaussian projection and about precious adjustment of a point and a direction. these methods include three dimension constrained adjustment with rectangular space coordinates as unknowns, three dimension constrained adjustment with geodetic coordinates as unknowns, two dimension constrained adjustment with plane baseline vectors as observations, two dimension constrained adjustment with differences of plane coordinates as virtual observations and precious adjustment with one point and one direction constrained. Taking a high-speed railway section of the GPS measurement data, it calculates various adjustment methods and has a comparative analysis.Secondly, the thesis discusses the basic concepts of projection distortion and how to calculate the projection height and the central meridian altitude according to given tolerance about projection distortion. Following it discusses the Gaussian projection, cutting Gauss projection, lambert projection, oblique cylindrical projection model about their algorithms and application. Which focuses on the oblique cylindrical projection. Oblique cylindrical projection have advantages in the control distortion about engineering net aspects relative to the other projection models. It has a test Taking a actual data in high-speed railway.Third, it discusses difference between the surface of engineering construction and engineering projection. Finally, based on the GPS Control Network Project deformation theory and the projection theory,, the author developed a precision engineering GPS adjustment software (MGPS) which meets the needs of large-scale engineering using Visual C# language as a development tool.