Smoothing method of Class A Surfaces for auto-body based on UG

The conception and desirable quality of auto-body Class A Surfaces are presented. The processes of smoothing Class A Surfaces are discussed by taking bumper as an example. The arranging of control vertex, patch and degree of surfaces are presented to assure the quality of surfaces in basic surfaces smoothing. Theoretical intersecting curves of basic surfaces are emphasized in transitional surfaces smoothing. And problems are analyzed in trimming basic surfaces with transitional surfaces boundary.