Mirror links and be able to export to IFC / Use Path of Travel

[angelica.rodriguez.3d]

Some companies use links to have apartment types in multi-unit buildings. It is necessary to use an apartment type and mirror it as it will be build.
Unfortunately, when an IFC is required, mirrored links won't export. 
Also, when we need to use the Path of Travel tool, mirrored links stop the tool from working. 
I wonder if @angel_velez can have a look at this issue, please?

[RDAOU]

When a link is mirrored, its internal coordinate system can become inverted or misaligned with the main model's coordinate system. Additionally, IFC relies on consistent world coordinates and transformations, and mirrored links can break this consistency and cause undesirable and misleading information in the IFC. In a mirror left becomes right, hot becomes cold, structural components reverse polarity…and so many other things which at first glance some users might not notice or realize.

On such projects (open BIM environment)

1. Either have two separate unit types (mirror images of one another) and both are linked.
   • link the unit into a blank model,
   • mirror it,
   • bind it
   • review and amend any components which may need particular attention 
   • then save that as a new type and use in the host
2. Alternatively, bind the linked units in the host model and manage them as groups

The path of travel should work normally with mirrored links (see GIF)

[angel_velez]

Hi Angelica, I can't speak to the Path of Travel tool, but I can explain the mirror links issue.  Basically, there is no way to have a mirrored local placement transform in IFC, which means that to export a mirrored link, we would have to go inside the document and effectively mirror everything ourselves.  

Do also note that while mirrored links are convenient in Revit, they aren't 100% accurate - for example, the door operation doesn't changed in a mirror.

[angel_velez]

Hi Angelica,

I can't speak to the Path of Travel but I can to the IFC issue.  Basically, IFC doesn't allow for a mirrored local transform, which means that if we want to exported a mirrored link instance, we need to go into the link and mirror every element ourselves.

Also note that while mirrored links are convenient in Revit, they are only approximations: for example, the door operation parameter doesn't "mirror" (no parameter does).

[SteveKStafford]

To add to the other replies...in architecture/engineering we are comfortable with the abstract idea of this is the same but mirrored. In a model environment a mirrored version, merely flipped over, will result in "right handed" elements looking like "left handed" but still reporting data based on their "right handedness". A sink's hot and cold valves are reversed in a mirrored version, to mention just once situation.

Far better for us to deal with reality and create a "mirrored" version of the design with elements in their correct orientation...place the mirrored condition versions where they belong so the model contains elements that are oriented correctly for their use.

...If we're only interested in 2D drawings printed on paper then "who cares"...but if we are moving toward a data driven model world...then the model ought to faithfully represent that situation. No?

[angelica.rodriguez.3d]

I guess you guys are correct, it is just the limitations of the software to 'read' orientation that will force us to modify our workflows from having 10 links to 20. In architecture doors would also require a correct reporting of orientation, but, for coordination of models with M&E teams we would expect the (impossible) IFC with mirrored links to suffice.

What alternatives would we have to achieve the same result without resourcing to mirroring links? At the moment the only solution is to bind links, but not sure that elements in binded mirrored ex-links will present the inner data correctly.

[RDAOU]

It depends on what you include in those linked units. However, the proper solution is to model the "verse" and "reverse" as two unique links.

Binding a mirrored unit does not automatically reorient everything; some elements will still require the user's attention, particularly those whose orientation relative to Revit's Cartesian system and world coordinates is crucial (see the snapshot from my previous reply). If you are only including architectural components and furniture in those units, then there isn’t much to worry about.

• In Architectural Discipline is the easy one where maybe the worst thing to consider is the doors operation. Opening direction is a parameter. Binding the link will not automatically change that parameter value. You would need to either do it manually or rerun script to do it.
• MEP (ex: Plumbing Fixtures Connectors): A mirrored link would flip the hot and cold water connectors. Binding the mirrored link will not flip them back to the correct layout (Hot Left / Cold Right) ... see GIF below
• Structural elements...Mirroring a Link and/or binding the Mirrored link will affect the analytical components of the structural framing (These should not be added into the units' link if you intend to mirror them.