Automatic Generation Method Of 2D Entities Based On IFC Standard

The automatic generation of shop drawing is an important part of the application of Building Information Modeling(BIM),and it helps to play a significant role of BIM technology in the whole life cycle of contruction project.Establishing the automatic generation of 2D entities such as dimension annotating and component cross section based on Industry Foundation Class(IFC),can lead to the optimization of 3D model in the field of expression of spatial arrangement and component size.Also,due to the situation that the data from different BIM software tools can’t be interoperated caused by 2D drawings which are generated respectively,the proposed method can lead a way to automatic generation of 2D drawings of integrated model and form the association between 2D drawings and 3D models.As research object,IFC-based 3D model is analyzed from which the dimension sizing and cross section information extraction mechanism is developed by the relationship of 2D entities and 3D model.In consequence,2D IFC entities which expressing dimension and component cross sections are automatically generated according to the IFC-based representation mechanism.Firstly,the geometrical information is extracted from the spatial orientation and shape representation of the 3D component model,while the material information is extracted from the attribute expression and association relationship of entities.Then,combined with the expression mechanism of 2D entities in IFC standard,the shape representation of 3D model is transformed into dimension and cross section information,while the material expression is transformed into hatching information via the processing methods such as information classification and coordinates transformation.Next,combined with the parameterized information transformation mechanism,2D IFC entities associated with 3D model are generated with the composition of spatial orientation,shape expression and association relationship.Finally,the automatic generation method of 2D entity is verified with proposed cases.