So it's always a hot topic how to transform GPS ellipsoidal height into level elevation and to keep certain accuracy.

The accuracy of Orthometric Height will be directly affected by ellipsoidal height precision during GPS height transformation, therefore, the detection of gross error is very important.

In this paper, we study a new kind of stochastic process from the family of distribution of ellipsoidal equal height, that is, the process of ellipsoidal equal height.