The concept of feature was introduced because of need to integrate the design and the manufacturing activities. Therefore, the generation of features usually occurs after design completion. However, in recent product development approaches such as concurrent engineering (CE), features need to be generated during design evolution. This paper presents an incremental feature generation (IFG) and feature modification (FM) approach applicable during design evolution, defined by constructive solid geometry (CSG) and boundary representation (B-rep). In IFG, a classified boundary component, obtained from boundary evaluation, is defined as a protrusion or depression (P/D) according to Boolean operation and convexity analysis. The existing features are then updated in accordance with feature interactions in the FM. The FM involves feature existence analysis and modification procedures. The modification procedures are : [ ) decide whether the remaining part of an existing feature is valid for a feature definition, 2) update it as a new feature and 31 define the feature relationship. In the IFG approa,zh, the geometry of the current design step is automatically isolated by Boolean operation and defined
as a protrusion or depression (P/D) w~thout convexity calculation of topological entities such as edges or l:ace sets. The above procedures are performed through tracing Boolean operations and convexity checking of an intersection edge loop generated during design e,,olution.