jgg     2013 33 (2):  124-127    ISSN: 0412-1961  CN: 21-1139/TG EXTRACTION OF URBAN BUILDING FACETS FROM LIDAR POINT CLOUDS College of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083 Received: 2012-09-23  Revised: null  Online: 2013-04-18 Supporting info