## 6 AR-Based Construction Guidance
### Information Fusion of BIM and AR  
\"Integration Definition for Function Modeling\" (IDEF0) is a method for graphically representing the specific steps, operations, data elements, and connections between the various activities required to complete a task [58]. IDEF0 models comprise of boxes and arrows. A box represents a system function, and an arrow represents the information required by the box. This information is composed of four parts: input, output, control, and mechanism. The process of integrating BIM and AR information is illustrated using IDEF0 [33], as shown in Figure 6. It encompasses four main activities: collect data about the building (Node A01), build the seismic model/retrofitting animation (Node A02), upload the model and animation to the AR platform (Node A03), and view the model/animation (Node A04).  
As shown in Figure 6, the inputs are the \"original building drawings and models\" and \"post-earthquake site media information\", and the final outputs are the AR model usage scenarios for the different retrofitting stages. The implementation of the four functions above is controlled by \"BIM basics\" and \"Post-earthquake building assessment and restoration basics\", and the \"Manager\", \"Expert\", and \"Designer\" are employed as the mechanisms for driving the implementation of each function. The \"Manager\" participates in all activities as the scheduling manager of the project.  
Figure 6: BIM-AR information combination flow.  
The function \"Collect data about the building\" operates based on the input information. During this period, building-related information is collected according to the \"Information collection template\" proposed above, and \"Integrated data\" is output. This output will also be used as input for subsequent functions. The above activities should be performed in cooperation with the \"Designer\".  
The function \"Build the seismic model/retrofitting animation\" has \"Retrofitting design scheme\" and \"Integrated data\" as its inputs. The output is \"Model and animation\". To achieve this function, the \"Designer\", \"Animation engineer\", and \"BIM engineer\" must work together to process the model in accordance with the \"Damage information coding guidelines\" and \"Multi-level expression method of damage\", and must follow the constraints imposed by the \"Appraisal results\".  
The input of the function \"Upload the model and animation to the AR platform\" is the output \"Model and animation\" from A02. This function needs to be performed not only by an \"Operator\", but also by using \"AR software\" and strictly following the \"Use rules of AR platform\". The output of this function is the \"AR model\"; it can be used by different types of AR devices and applications and provides input information for the implementation of subsequent functions.  
The function \"View model/animation\" takes \"AR model\" as an input to perform its activities. It can be used for appraisal of seismic damage, analysis of an overall design, guidance for construction crews, and assistance in completion and acceptance. For different work purposes, each participant selects the appropriate device, and follows the \"Use rules of AR platform\" to output the AR model scenarios for the function. For example, retrofitting personnel who need to perform \"Construction guidance\", i.e., \"Construction crews\", should use \"Mobile phone\" to view models and animations under the guidance of the \"Use rules of AR platform\".