IFCAlignment

camontellano

Does Someone know where to start reading documentation on how IFC Aligment works? Are objects simply placed along an Alignment can they be sweeped between two positioned profiles? Are horizontal and vertical Alignment separated from each other. What types of curves are supported or how are they to be described?
Any help here would be very greatly appreciated.

steverugi

@camontellano said:
Does Someone know where to start reading documentation on how IFC Aligment works? Are objects simply placed along an Alignment can they be sweeped between two positioned profiles? Are horizontal and vertical Alignment separated from each other. What types of curves are supported or how are they to be described?
Any help here would be very greatly appreciated.

same here
also some hint on the API ifcopenshell.alignment would be greatly appreciated as well
thanks

Alox__

I'd like to know more too.
BTW, if I can help, I've seen a video on YT in the past where a road was modelled using an array along two lines.

walpa

This wiki has a history of the ongoing implementation. It looks like the features will be in the ifcopenshell v0.8.0 version.
Can @civilx64 or @aothms help us ?

aothms

I know somebody who has the perfect whitepaper on this. @Rick_Brice He's travelling now, but my recommendation would be to add it to the Wiki here https://wiki.osarch.org/index.php?title=IFC_-_Industry_Foundation_Classes

civilx64

TLDR; the implementation of alignment geometry is substantially complete in v0.8.0 thanks to the fabulous work by @Rick_Brice with support from @aothms.

The BlenderBIM add-on is also picking up this functionality as of very recently - see https://github.com/IfcOpenShell/IfcOpenShell/issues/4727
This includes generating 3D alignment geometry for horizontal, vertical, and cant geometry as well as placing objects at a given distance along an alignment (linear placement) and generating solid geometry from cross-sectional profiles at varying distances along an alignment (swept surfaces).

civilx64

@camontellano said:
Does Someone know where to start reading documentation on how IFC Aligment works?

I recommend that you start at the very beginning - the very best place to start: IfcAlignment.

Alignments are described via two separate but complimentary mechanisms: business logic and geometric representation. The former tends to resonate with industry practitioners and domain experts whereas the latter is more familiar to those with previous experience implementing IFC.

Are objects simply placed along an Alignment can they be sweeped between two positioned profiles?

Both! See IfcLinearPlacement and IfcSectionedSurface.

Are horizontal and vertical Alignment separated from each other.

Yes:
Horizontal: IfcAlignmentHorizontal for business logic and IfcCompositeCurve for representation
Vertical: IfcAlignmentVertical for business logic and IfcGradientCurve for representation
Cant: IfcAlignmentCant for business logic and IfcSegmentedReferenceCurve for representation

What types of curves are supported or how are they to be described?

Review the documentation on Segment Type enumerations such as IfcAlignmentHorizontalSegmentTypeEnum

Any help here would be very greatly appreciated.

Hope this helps!

Rick_Brice

@aothms I'm trying to create the whitepaper in the wiki but don't have permission to add figures. Any ideas how to get that permission?

theoryshaw

@Rick_Brice try now... i changed the permissions.

Rick_Brice

I have posted the whitepaper in https://wiki.osarch.org/index.php?title=IFC_-_Industry_Foundation_Classes/IFC_alignment

Rick_Brice

@camontellano @steverugi here is the whitepaper @aothms was referring to.
https://wiki.osarch.org/index.php?title=IFC_-_Industry_Foundation_Classes/IFC_alignment
Your feedback on how to make it better is appreciated.

steverugi

Hi @Rick_Brice

@camontellano @steverugi here is the whitepaper @aothms was referring to.
https://wiki.osarch.org/index.php?title=IFC_-_Industry_Foundation_Classes/IFC_alignment
Your feedback on how to make it better is appreciated.

thanks for the valuable info, I am going to share it with my colleagues in charge of alignment design (I am the quantity guy) and will let you know, cheers

longhairjnr

Hey guy's I might be a bit late to this whole thing but I was wondering with the BlenderBIM Implemnetation of the Alignments from IFC, does anyone know if there is a way to generate Long sections (SVG/DXF) via BlenderBIM? As this would be one of the best game changing things from the Linear Infrastructure guys, it might even be enough for me to convince the company to try out documenting from BlenderBIM for things like Retaining walls/Noise Walls, then comes the push for our Bridges. :D

aothms

@longhairjnr currently BlenderBIM can visualize the alignment geometry and/or sweeps and interact with it from a cartesian coordinate perspective. Anything domain specific, as well as a more linear mode of interaction with the geometry, or accessing parameters regarding the (transition) curves, still need to be built. We're planning to build a roadmap of the authoring/domain specific interaction functionality required. Feel free to pitch in here https://github.com/IfcOpenShell/IfcOpenShell/issues/4933

Ace

Hey @aothms With the latest v0.8.0 release, Alignment was mentioned for viewing, is authoring still on the roadmap or is there a way to use it with the newest release?

aothms

@Ace Definitely. This is what I proposed earlier https://github.com/IfcOpenShell/IfcOpenShell/issues/4933 Basically to either wait for community members / Civ Eng students to come on board to sketch what this would look like. We're a community :) So if there is somebody who wants to take ownership to move this forward I can help connect the dots.