# A BIM Based Framework for Damage Segmentation, Modeling, and Visualization Using IFC
## 2 Background
### Damage Data Applications  
Based on the damage data, different applications process the given data. The processing of data is divided into visualization and simulation. This study focuses on visualization. Visualization is necessary for assessment and planning. Planning covers several sub-tasks: planning of non-destructive testing, inspection, and maintenance procedures.  
Damage and bridge data have to be visualized for different use cases. Most studies address the visualization for the task of assessment. [PERSON] et al. developed a framework to assess historic buildings. The Historic Building Information Model (HBIM) includes inspection and survey results to provide a structured overview of defects to engineers [35]. The visualization mainly consists of tabular structured text and related photos.  
Based on Structure from Motion (SfM) and laser scans, 3D point clouds of damaged bridges may be generated. [PERSON] et al. have shown how to generate those point clouds and highlight damaged sections in such a point cloud [36]. This approach provides a 3D surface model of the damaged bridge. The assessment needs overviews of registered defects and related components. A labeled point cloud does not provide the related semantics needed.  
BIM aims to incorporate raw data, such as photos, measurements, and point clouds; furthermore, conclusions and deductions from stakeholders, for example, task planning or conditions states. [PERSON] et al. have used a BIM model of a bridge and added the condition state of the individual components. Additionally, they highlighted the benefits of proprietary software, that include images and textual information [37]. These two different visualizations are the first step towards virtual model based inspections.  
A reasonable assessment also requires geometric information, such as the defect position. [PERSON] et al. [38] target this problem by adding damage cubes to the BIM model. Visualizing damage and bridge data according to the requirements of national inspection manuals have been covered extensively. However, the proposed approaches are not open for additional tasks, views, and use cases. This is necessary because it is not possible to predict future use cases without them. Hence, this study focuses on addressing assessment requirements and using open standards.  
Apart from visualization, using 3D damage data may be utilized for structural analyses. Based on geometric damage information, the Finite Element Analysis (FEA) model may be generated by using adapted material parameters [39]. However, in-depth information on how to exchange damage data with third party software is not provided in this study. [PERSON] et al. developed a framework for bridge assessment based on a linked model approach [40]. Such linked models have the disadvantage of data dispersion. For later data exchange, it is beneficial if all data is stored in a single file. [PERSON] et al. proposed an open framework on the basis of point clouds [41]. However, the photos for damage detection are generated based on the point cloud that may lead to information loss. To omit this limitation, this study used photos of the inspected bridge as input.