A New Algorithm for Block Adjustment of Independent Models

For three-dimensional block adjustment of independent models there are seven unknown parameters in every model.To solve these unknowns,the algorithm socalled alternating "plan" and "height" adjustment has popularly been used.Based on the analysis of the characteristics of gravity-centralized coordinates used in the adjustment prcoedure,a new algorithm is proposed in this paper,with this method the seven parameters are divided into two parts:three for shift(dxg,dyg,dzg) and four for rotation and scale change(dΦ、dΩ、dκ、dΔλ).It has been verified theoretically,that the three shift-correction values can be obtained by calculating the mean values of the coordinates of all tie points at every iteration and needn't be involved into the normal equations.Therefore,only four unknowns for each model remain to be solved.Two programs have thus been written based on the conventional and the new algorithms and run with synthetic data for comparison.The result shows the correctness and advantages of the new algorithm.The new method takes not only much shorter computation time but also much smaller core storage units as compared with the conventional one.