Research on Algorithm of Building Overall Contour for Planar CAD Drawing

In the study of automatic modeling of building climbing frame based on building CAD plans, recognizing the building's contour is a very critical step. In order to realize the automatic recognition of building contour and realize from 2D building drawings to 3D building entities, this paper generates 3D Autodesk Revit model from building plan AutoCAD 2D graphic recognition of building contour to realize BIM reconstruction. On the basis of adaptive chunking algorithm, combined with convex packet algorithm and depth search algorithm, an algorithm based on the recognition and processing of straight line Line and multi-segmented line PolyLine in architectural CAD drawings is proposed, and the building contour is automatically acquired and generated into a 3D entity. The algorithm links the CAD drawings in Revit, reads the text information by connecting to the. dwg database with the help of Teigha library, filters the straight lines and polylines of the target layer, processes them, and obtains and stores the endpoint information. The points on the building contour are obtained by scanning and comparing the endpoint coordinates. Finally, all the points on the contour are connected in an orderly manner to get the 2D contour of the building. Finally, the contour is solidly stretched in Revit to get the 3D building solid, which lays a certain foundation for the subsequent research on the automatic generation of the 3D model of the climbing frame. The algorithm is of great significance for realizing the automatic modeling from AutoCAD 2D graphics to Revit 3D model and the automatic modeling of building climbing frame, which has strong application value in the field of computer-aided building construction design.