Feature Identification from Vectorized Mechanical Drawings

摘要

Algorithms to identify 2-D geometric features from the vectorized form of a scanned engineering drawing have been developed. These are based on a pattern matching process where the entities present in the vectorized drawing are checked for specific pattern primitives. The pattern primitives present in an entity are compared with the overall direction of the entity to arrive at the 2-D features that are present. A library of 2-D geometric features has been developed for comparative purposes. For 3-D reconstruction and feature recognition a separation reference point is first found in order to group the entities into their respective views, i.e., top, front, and right side view. This separation reference point is then used to transfer the points belonging to the three orthographic views, expressed in the 2-D coordinate system, to a 3-D coordinate system. The 2-D feature recognition algorithm is applied to each of the three views and the 2-D features recognized in each view are combined using a set of matching primitives and matching rules to arrive at the 3-D features present in the component. 3-D features with linear sweep or rotational sweep and uniform thickness can be recognized.