The multiple measuring stations are always used to form measuring net in the geometric measurement of large scale workpieces. This method not only extends measuring bound
but also enhancing the redundancy. The spatial data registration of multiple measuring stations is based on singular value decompose
and then the data is fused by the optimum fusion criterion of matrix weighting linearity minimum variance. The validity of fusion criterion is proved by theory and simulation test
showing that the fusion precision is superior to each partial precision. The criterion has been applied to measuring net in tunnel component.