SIFCEXPORT - Representations

When using the SIFCEXPORT command to have SOLIDOS draw the device in the IFC file, you must decide how to represent certain elements.

There are two ways to represent solid elements in IFC using the SOLIDOS program:

1. All device components are triangulated
   In the SIFCEXPORT command screen, Object / Use BREP is set to YES, or the device component Expose Solid is marked to use BREP
2. Device component geometries are mapped to IFC classes
   In the SIFCEXPORT command screen, Object / Use BREP is set to NO and the device component Expose Solid is marked to not use BREP
   In this case, device components will be mapped to:
   • IfcExtrudedAreaSolid - profile extrusion
   • IfcSphere - simple sphere
   • IfcRevolvedAreaSolid - profile revolution
   • IfcFacetedBrep - solid modeled via Boundary Representation, with face triangulation
   • IfcBooleanResult - Boolean operations: UNION, DIFFERENCE, and INTERSECTION
   • IfcMappedItem - item cloning with spatial transformation
   • IfcBlock - rectangular prism (not supported by some viewers)
   • IfcSurfaceCurveSweptAreaSolid - supported by any viewer?
   • IfcSweptDiskSolid - a circle extruded along an axis; rarely appears in SOLIDOS devices
   • IfcSectionedSpine - sections distributed along an axis; did not work in most viewers tested

SOLIDOS actually generated the crossed-out items, but since viewers cannot render them, it converts them to IfcExtrudedAreaSolid, IfcRevolvedAreaSolid, and IfcBooleanResult.

When solid geometry is triangulated (i.e., BREP representation), one must configure whether the face triangulation will be high-precision—generating a huge file—or low-precision—generating smaller files. This directly impacts the quality of the IFC file and the processing time required. Control over this triangulation is handled by the device's modeler, specifically within the Expose Solid tool, under the IFC category parameters:

The default values ??for these properties are zero. Generally yields good results

For the device shown below, the triangulated version with default parameters (all set to zero) was 115 KB, whereas the optimized version was 6 KB—representing a nearly twentyfold increase in file size:

See Also:

• SIFCEXPORT - IfcExportAs - Which IFC class the device belongs to
• SIFCEXPORT - PropertySet - Which properties will be exposed in the IFC file
• SIFCEXPORT - Viewers - Considerations regarding viewers and how they process geometries
• Export Solid
• Command SBUILDER
• Command SIFCEXPORT