21 Object Matching 21.1 Various matching methods ..ti 21.2 Methods through localization/registration 21.3 Classification of matching methods 21.4 Problem statement. 21.4.1 Distance metric 21.4.2 Distance between a point and a parametric surface 21.4.3 Distance metric function 21.5 Matching problems: CGWOS, CPWOS, CGWS or CPWS