4. Data Conversion from IFC Files to 3D3S Files
4.1 Data Structure
The primary data structures involved in this process include nodes, units, and floors.
Node Data Structure:
Class Node {
int NodeID; // Node index number
double CoordinateX, CoordinateY, CoordinateZ; // 3D coordinates of the node
int ConstraintType; // Constraint type of the node
ArrayList NodeInElements; // List of units connected to this node
}
Unit Data Structure:
Class Element {
int ElementID; // Unit index number
ArrayList NodesInElement; // List of nodes within the unit
int SectionType; // Unit section type
int ProperType; // Material type of the unit
int ContainedInFloor; // Floor on which the unit is located
int ElementType; // Unit type
}
Floor Data Structure:
Class Floor {
int FloorID; // Floor index number
double Elevation; // Elevation of the floor’s top
double FloorHeight; // Height of the floor
ArrayList ElementsInFloor; // List of unit indices on the floor
}
4.2 Example Implementation
This article demonstrates the development of a data conversion interface using VC#.NET within the Visual Studio 2005 environment. Once the architect completes the building model, the IFC file is exported. The interface then automatically extracts geometric, sectional, and material information of structural components from the IFC model file.
Structural components handled in this example include concrete columns, beams, walls (with door and window openings), slab components, as well as steel columns and beams. After converting the IFC file into a 3D3S data file, the data import interface of 3D3S software is used to automatically generate the building’s structural model.
It is important to note that this tool does not replace the expertise of structural engineers. Instead, it aims to relieve them from the tedious and repetitive modeling tasks, allowing them to focus on optimizing structural design and improving overall quality and efficiency.
5. Conclusion and Future Work
This project is based on TNO’s IFC engine DLL development toolkit and develops a data conversion interface to automatically generate a 3D3S structural model from building models created in Autodesk Revit software.
The IFC standard is continuously evolving, with the latest version IFC2x4 released in May 2010. Therefore, the conversion interface presented here requires ongoing updates to stay compatible with new IFC specifications.
While the current interface can extract geometric, sectional, and material data from building models, a complete structural model also requires information such as loads and constraints. Developing methods to extract load and constraint information from building models remains an important area for future research.
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