Dimension Recognition and Reconstruction in Vectorization of Engineering Drawings

Dimension recognition is an important aspect of automatic engineering drawing understanding In this paper, a multi entry dimension recognition algorithm is presented It starts searching for dimensions from elements of various types already recognized When an element cannot be recognized under normal conditions, other elements are tried to obtain a primary confirmation about the dimension structure Then the threshold is relaxed and used to recognize the element again Therefore, dimensions with much degradation and disturbance can be detected effectively Also presented is a geometry reconstruction method based on the coordinate grid Every dimension and associated entities are adjusted under the overall guidance of the coordinate grid, which satisfies the requirement of data precision for drawing reuse