Correcting the CL symbol in mirrored Revit links

The automatic 'Centreline' capability on Revit dimensions can be really annoying when they pop up unexpectedly.  But when you actually need them it is very useful to be able to just change a property of the dimension family to make the CL symbol appear.

I have seen people just placing many instances of two little pieces of overlapping text, one being C, the other L - all because they didn't know about this feature.  That is criminal!  And its a nightmare when dimensions need to be adjusted.

Mirrored Centreline Dimension Symbols

What happens when you mirror the elements and dimension?  In most situations, Revit handles it perfectly well, because the CL is a symbol family, and Revit automatically corrects the symbol orientation.  However, there is one situation where it does not work:

• If the dimension is in a linked Revit file that has been mirrored - normally you would not see the annotation in the linked file, but if you set the view properties for that link to be 'By Linked View', then the dimensions in the mirrored linked file become visible.

• In this situation, the symbol may not be displayed correctly, depending on how the symbol family was created:

CL symbol in Mirrored Link

• The OOTB centreline family is actually made up of arcs and lines (not text) - this symbol does not display properly in mirrored linked files.

I was recently asked to solve this problem, so I searched high and low for settings in the dimension and in the symbol family that might solve this.  I found nothing.

• Next I tried converting the symbol from lines to actual text in the family - I'm not sure why it was originally done as lines anyway?
• This needs to be made up of two pieces of overlapping text - in the symbol family, not the project file.
• In this example I made the text using a font that was clearly not lines - 'Algerian' was the first suitable windows font that I found, to make the demo clear.

• In the original file it looks fine, as expected.
• Once I looked at it as a mirrored linked file, another problem showed up:
• Each letter was displayed correctly, but displaced sideways

• Aha, it must be the text justification, I thought.

 

• But no, that made no difference whatsoever when I tried centre, left or right Horizontal Align.  Revit is just mirroring each piece of text around the symbol centreline, then flipping the text back again around its own axis.

Weird Workaround

So what was the solution?

• Edit the text in the symbol family - Put a space after the C and one before the L.
• Shift the letters accordingly. 

• It wasn't perfect to start with, so I had to shift the text around a bit, or add a second space after the L

Weird behaviour in Revit requires weird thinking workarounds!

Creating Sweeps in Revit Mass - CME Part 4

Part 4 of my series on  comparing the five traditional form creation tools with equivalent techniques in the Revit Conceptual Massing Environment.
Previously we analysed the creation of extrusion forms, Blends and Revolves in the CME.  Now  we sweep on to the next form:

Part 4:  Sweeps

 Creating a Sweep in the Conceptual Massing Environment has a few unexpected rules and exceptions - some of which you can use to your advantage.

• First you have to create a path for the sweep, consisting of one or more chained lines, arcs or curves (model or reference) - this is one of the few occasions that you can have multiple element segments to a path in the conceptual massing environment (if not the only one).
• Then create a profile that is perpendicular to the element of the sweep that it intersects.  

 

• NB. If the profile is open, Revit only allows a single element for the path

• You can place the profile on a convenient perpendicular work plane but the easiest and most reliable way to do this is to host a point on the path then host the profile on the point (set the point reference as work plane) - as recommended by Autodesk.

• Select the profile and path; 
• Create form 
• It should create the sweep

• However, it may give a message ‘Unable to create form due to self-intersecting geometry’

• The most common reason might be if you have arcs/curves on the path where the radius is too small to make the transition between straight sections on the inside, as in the example below where the middle arc radius is very close to failing – two profiles are almost meeting each other on the inside of the corner

• To avoid this problem you could make the path radius larger than required to start with, then reduce it afterwards so that you can see where any problems occur; alternatively, make the profile smaller, then increase it after the form is created - check in X-Ray mode to see where profiles may be close to intersecting. 

• To edit the path or profile:
  • If the profile was made from model or reference lines, it can be edited in sketch mode using ‘Edit Profile’ once any part of the form is selected;
• The path (model or reference lines), can be edited in sketch mode – in a very limited fashion, eg. changing the radius of an arc; in this case you may need to use the X-Ray mode to be able to see the path to select it.

Hollow Sweep (Nested Profiles)

In the Traditional modelling environment, Revit usually allows you to have nested loops within a profile in order to create a hollow form.  The Conceptual Massing Environment is less forgiving - I have only found two situations where it is allowed:  One is Revolves and the other is:

• Revit does allow a profile with a loop inside a loop, but only if the profile is made from lines/arcs – not from a loaded family profile;
• You could offset/copy the original profile (or draw a new inner loop profile) 
• Select both profiles and the path elements
• Create form
• Hopefully it will create a hollow form 
• It will show joint lines for each segment of the path

• If you want to use a loaded family as the profile, It does not allow you to create a hollow form in one command:
• You need to create two separate forms, one solid and one void;

• In this situation, it is best to keep the path as reference lines, so that they can be used for both forms;

• Select the path plus outer profile;

• Create the solid form

• Make it X-Ray so that you can see and select the path and the inner profile

• Select the inner profile and the path
• Create Void Form

• It should cut the void from the solid automatically

• Interestingly the combined form does not show any joint lines (where transitions are tangential) – this is desirable in the project

Joint Lines

• Prior to seeing this result, I tried hiding the joint lines in the project by putting them into a subcategory or associating a visibility parameter but that affected the whole form, not just the joint lines.

• Making the original profile a reference line does not hide the joint lines either

• It looks like we may have to create combined solids just to solve this.

Youtube

Youtube links for those who don't like reading:   Create a sweep in CME