Boundary Representation (Body, Tessellation and Sweep Solid)

f.zanoni

I created a rule to identify beams with Boundary Representation geometry. However, I noticed that not all beams with this geometry were recognized by the rule.

When analyzing in X BIM, I observed that the ifcRepresentation of these beams shows some differences:

The beams that were identified have ifcShapeRepresentation defined as (‘Body’, ‘Swept Solid’).

The beams that were not identified have ifcShapeRepresentation defined as (‘Body’, ‘Tessellation’).

My question is: could this difference impact the result of the rule?

Reference images

First image – shows a beam identified by the rule, with geometry = Boundary Representation and ifcShapeRepresentation = Swept Solid.

Second image – shows a beam not identified by the rule, also with geometry = Boundary Representation but with ifcShapeRepresentation = Tessellation.

Matti

For Solibri the IFC geometric representation item matters more:
e.g. IfcExtrudedAreaSolid or IfcBooleanResult

IFC has a lot of different geometric representation items.
In Solibri the IFC items are converted to few choices:

Brep
Extrusion
Solid

Anyway this is not affecting on checking results in general. The different geometry types might affect on speed because of some optimizations.

f.zanoni

Hi @Matti

Thanks for your quick reply and support.

I’m sending you a message with more details along with the IFC file, so you can analyze why the rule doesn’t detect all geometry with boundary representation.

Matti

I tested your model. The rule works, if you choose the both “Boundary Representation” values in your filter.
There are actually two different geometry types with equal name and that causes this confusion. Just curious, what is the goal of this rule?

f.zanoni

Hi @Matti

I noticed that two geometries appear with the same name, but since the writings are identical, I was wondering why Solibri creates two geometries with the same name?

The purpose of the rule is to check whether the beams are modeled continuously or modeled between columns. If the beam is modeled continuously, its geometry will be Boundary Representation. If it is modeled from column to column, then it will be of the Extrusion type.

Would you suggest another way to identify whether beams are modeled continuously (the same beam but with several columns creating sections along it)?

Matti

You could also use inversion, the geometry of the beam is not extrusion
I don’t know any other way for checking this. There could be authoring tool specific property sets that differs between modeling style and could be used for the same purpose.

JSN

I use it in a different context and noticed the same. I was also wondering why there are two different types of BREPs which look like the same?
Actually I don’t have them in all models and without reading this I would still scratch my head and wonder why I am missing stuff.