Solid reconstruction from orthographic views using double stage extrusion (2)

The entities involve both solid and dashed lines in each view. In the first stage, an double stage extrusion exterior contour region in each view is swept along its normal direction according to the corresponding object dimension. As a result, three extrusion-solids are produced. Intersection of the three extrusion-solids forms a basic-solid. Next, all interior entities of each view are treated by a filtering process. If all interior entities are discarded in the filtering, the second stage will be skipped and the basic-solid becomes a solution-solid. On the other hand, if any interior entity remains after filtering, they are processed in the second stage to generate an excess-solid. In this case, the basic-solid subtracts the excess-solid to form the final three-dimensional solution-solid.