Graphic closed field selection treatment manner

摘要

PURPOSE:To automatically and surely extract a closed area by branching a branch point in the clockwise direction to trace a segment, and when the rotational direction of the whole tracing coincides with the branching direction of the branch point at the time of returning the tracing up to the branch point to be a start point, defining the obtained area as a minimum closed area. CONSTITUTION:A branch point extraction processing mechanism 5 finds out the intersecting point of a cross type intersection e.g. and the contact of a T-shape type contact point from broken line data 7 and stores these values in a storage device 2 as branch point data 8. A closed area extraction processing mechanism 6 starts the tracing of a segment from a certain branch point, branches the tracing line surely to the right at each branch point, and when the rotational direction of the whole tracing coincides with the branching direction of the branch point at the time of returning to the start point after rotating by one circle, the traced closed area is decided as the minimum closed area. Even when the number of lines constituting the closed area of a graphic to be processed is many or the number of closed areas is many, the minimum closed area can be surely decided.