Research On BIM Collaborative Design Based On The Partial Model Version Control

With continues development and growing application of BIM(Building Information Modeling),this concept has been deeply rooted.BIM mainly solves the huge data information delivery and sharing requirements in the construction industry.With the scale of BIM application continues to expand,BIM has been used in the whole lifecycle of the building,e.g.the architectural design,survey,construction,cost estimation,operation and maintenance.The scale of architectural design is rising while the data granularity is more and more refined.It is therefore necessary to provide efficient collaboration support for different project participants.At the same time,in view of the fact that the BIM model with large amount of data is difficult to use and difficult to manage,it is necessary to design an effective model management mechanism to improve the ease of use of the BIM model and domain-specific customization support of BIM model for different stakeholders.In order to realize customized BIM information on demand for different stakeholders,a partial model generation method based on IFC(Industry foundation class)attribute extraction method is proposed.By analyzing the IFC classification and IFC entity association mechanism,an partial-model is extracted from the IFC model according to the domain model information requirements.The data density of partial model is improved and the complexity of the model reduced by emoving the definition and reference relationship between the domain requirements and the specific requirements.This method is implemented and validated based on the open source platform BIMServer.Experimental results show that the extracted sub model has obvious advantages compared with the IFC complete sub model in data volume,data access time,memory resource occupation and network transmission speed.Secondly,in order to improve the availability of the model constructed,a version management mechanism is proposed based on the operation tracking mechanism by analyzing the features of object oriented IFC model and application environment.By monitoring and recording a user's operation towards the model entities,the reversion history of the model is in a complete way.The progressive backtracking of the version can be achieved based on the progressive accumulation or decrement of the operation record.Experiment result show that the proposed version management model is much more efficient than GIT,SVN and other file based version management model.Furthermore,while this method greatly reduces the dependence of the BIM model towards the IFC standard,the proposed method also ensure the consistency of the data model by providing the support of mutual mapping – the generated partial BIM model can be mapped back to the complete IFC model at any time.Finally,in order to realize the effective cooperation among different stakeholder with the domain-specific partial-models,this paper constructs a collaborative mechanism of multi-partial-model based the version tracking operation.Through the "E-M-M"(Extract-Modify-Merge)mechanism,it realizes the work mode with so called local partial model-based updating and the global model–based collaboration.It improves the usability of the domain-specific partial model acquisition.Thus,relevant parties in various fields can cooperate effectively in the concern of their partial-model.Experiment results prove that the proposed coordination mechanism achieve higher performance than traditional BIM cooperative mechanism in respect to customizability and resource flexibility.At the same time,this method has significant performance advantages in the data storage,response time,and network transmission overhead.