XAS80到CGCS2000坐标转换的自适应拟合推估算法

Adaptive Collocation Method to Coordinate Transformation from XAS80 to CGCS2000

借鉴自适应滤波思想,将相似变换作为坐标变换函数模型的趋势项,把模型变换后的残差看成随机场,通过自适应因子调整信号向量与观测向量的先验权比,尝试通过自适应拟合推估法进行坐标变换,并将其应用于1980西安坐标系(XAS80)到2000国家大地坐标系(CGCS2000)的坐标变换。计算结果表明,自适应拟合推估法的坐标变换结果精度明显优于相似变换结果和拟合推估变换结果。

After the establishment of 2000 Chinese Geodetic Coordinate System（CGCS2000）, it is one of major jobs to unify various coordinate systems to the CGCS2000. Because the similarity transformation methods applied in the practice for coordinate transformation are in general not so accurate to unify different coordinate systems, an alternative collocation is presented for coordinate unification. It is needed that the prior covariance matrices between the signals and the observations should be consistent with their uncertainties. Otherwise, the coordinate of the stations provided by the collocation transformation will be unreasona- ble. An adaptive collocation estimator is applied by which the contributions of the signals and the observations to coordinate transformation are balanced. The corresponding adaptive fac- tor is constructed by the ratio of the variance components of the signals and the observations. An estimator of the variance components for the collocation is used. Reasonable and consist- ent eovariance matrices of the signals and the observations are achieved through the adjust- ment of the adaptive factor. The actual calculation from Xi ＇ an Geodetic Coordinate System 1980（XAS80） to CGCS2000 shows that the accuracy of coordinate transformation is im- proved by using the adaptive collocation model.