jgg     2014 34 (1):  127-130    ISSN: 0412-1961  CN: 21-1139/TG COMPARATIVE STUDY AND IMPROVEMENT ON SEVERAL  DE-NOISING METHODS FOR DIFFERENT NOISE  1) Department of Geomatics Engineering, Central South University, Changsha 410083 2) College of Dayu, Hohai University, Nanjing 211100 Received: 2013-01-29  Revised: null  Online: 2014-01-23 Supporting info