[Test Case]: Aggregate Structures on Alignment - Junctions

[AlexBrad1eyCT]

Test Case Purpose

Please provide a brief description of the purpose of the Test case proposal

Test case covering the export of pavement/Element assembly made up of layers of courses forming the fringe case of a junction, which is placed and defined by an intersection of alignments.

Scope Summary

please provide some information around the scope of your test case proposal

Pavement definition aggregating a set of courses with alignment linear placement based geometry. test demonstrates the following criteria:

• Spatial Structure Relations
• Geometries
• Brep Geometry
  • Tessellated Geometry
  • Triangulated Irregular Network Geometry
  • Sectioned Solid Geometry
  • Sectioned Surface Geometry

Test Case Proposal

MVD Code: IFC4x3_AbRV
Exchange Code: E2
Name: Aggregate Structures on Alignment - Junctions
Test Code: ASAJN

Additional context

Add any other context about the test case proposal here.

Miro Dependence Card

[ccast1]

BreP geometry seems not relevant for this case : the main issue in a junction is to verify the continuity for the drainage on the surface in avoiding any "flash". BreP is not able to verify this information.

[ccast1]

Lars was answering to me on the junction issue this : "To describe geometries one can use e.g. sectioned solids/surfaces (swept along alignment curves), TINs etc." It's exactly what I mean in this case.

I don't know if the schema is helping, but If BREP is based on summit and lines calculated by the authoring tools, there are no real difference with the option said by Lars. In this case, every thing is OK

.

[SergejMuhic]

@ccast1 with breps the slopes are not stored explicitly but can be calculated, whereas we encoded this kind of an explicit slope definition/functionality into the data structure IfcOpecCrossProfileDef.

https://standards.buildingsmart.org/IFC/DEV/IFC4_3/RC4-voting/HTML/link/ifcopencrossprofiledef.htm

Look under attribute 5 Slopes.

This does not mean, however, that such a definition is suitable for junctions. Junctions can be much more complex than e.g. laybys.

[SergejMuhic]

Dear @ccast1 , I don't know why your reply is not visible here but I got it per email. You might want to post it here for the sake of transparency.

If we are talking about breaklines, you need to consider the IfcTriangulatedIrregularNetwork type of a brep representation:

https://standards.buildingsmart.org/IFC/DEV/IFC4_3/RC4-voting/HTML/link/ifctriangulatedirregularnetwork.htm

See attribute 6 Flags for the flag for breaklines.

[ccast1]

my comments were as follow: difficult to draw something more complex with the tools for powerpoint. CAD are still powerful. Nevertheless the junction on roundabout, or on interchange are based on the same approach. But it's no more a question of IFC and MVD.

What I want to underline, is the following aspect :

• in a junction, what it is crucial : the continuity of two lanes. Usually, for most of the software you have a common string to simulate the frontier between the two lanes. We can suppose this string will be part of the ifc model . If it's not the case, IFC is not able to solve anything. If it's the case, the string, as a break line has to be used either in the brep, or in the new concept of geometry based on alignement.
  So two points : the question of the break line is not part of the ABRV discussion, but the question of Brep rather than other way to create the solid is part of the MVD specifications. Question : Brep specifications are part of what ?
  and your answer is perfect on the brep specfication regarding "ifctriangulated...." Many thanks to take time for answering.