Discussion on the III-conditioned problems in Geodesy

Ill-conditioned problems are widely existed in Geodesy. To resolve this problem, many experts and scholars both at home and abroad are devoted to the research of the ill-conditioned problems. And they offer the methods to dealing with the ill-conditioned problems. There are ridge estimation, generalized ridge estimation, principle components estimation, Tilchonov regularization, singular value decomposition and virtual observational approach. This text mainly generalizes the basic principle of these methods, and simply argues the development of the ill-conditioned problems.