jgg     2013 33 (1):  145-149    ISSN: 0412-1961  CN: 21-1139/TG APPLICATION OF POINT MASS MODEL AND LEAST SQUARECOLLOCATION IN MULTI-SOURCE GRAVITY DATA FUSION Gao Xinbing1,2);Li Shanshan1);Li Hai2);Zhang Hongwei2); and Wang Yingjian2) 1)Institute of Surveying and Mapping, Information Engineering University, Zhengzhou 450052;2)61365 Troops of PLA,Tianjin 300140 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null