"Magic Height" for cutting in plan: What is it?

[robert.manna]

I know that I've either seen this behavior documented somewhere, or have seen it disscussed on AUGI previously. Though I'm not quite sure what to search for it under, and I don't really have the patience this evening to comb through numerous search results.

There is a magic height for walls, where no matter what your cut height in plan is set to, you will still only see the wall as projected and not cut. So lets say you have a 3' high partition, and your cut plane is set to 2', because the wall is not above the "magic height" the wall shows as being projected and not cut, even though the cut plane clearly intersects the object.

Now on to my question/problem. Has anyone seen the same behavior with casework families, and is there any work around? Case in point I have casework families that have 3D geometry describing the full cabinet. However, because the casework is apparently below the "magic height" no matter what height the cut plane is at, you still see the casework "projected". Furthermore, if I do increase the casework height above and beyond the desired casework height, I can eventually get the casework to "cut" in plan. Besides making use of symbolic geometry is there any work around for this? Does anyone know what the magic height it? Can it be adjusted? I'm not opposed to the use of symbolic geometry, I'm just trying to fully understand the conditions I'm operating under.

Thanks for any thoughts or help,
-Robert

[robert.manna]

I've been able to answer at least one of my questions. The magic height for casework seems to be anything <= 4' 1" (cut plane was @ 3' 0"). 4' 1/4" returned a projected view and not cut.

So thoughts on dealing with this issue? Or is it just too trivial.....

-R

[dbaldacchino]

Hey Rob, from memory, I believe it's 4'-0". What I'd do to get around this is the following:

a) Create a "documentation" level below your model level. So for example if you're trying to set up a first floor plan level, create a documentation level 4' below your Level 1.

b) Now you can create a plan view associated to this "documentation" level and set your cut plane to 5'-0" above it, which would correspond to a cut plane of 1'-0" above Level 1.

Hope this helps.

[David Conant]

For most types of families, Revit stores a pre-generated symbol of the family taken at the cut plane of the plan in the family file. This symbol is used whenever an instance of that family is cut in a plan view in the project. Why do we do this? To increase performance. Without this, Revit would have to look at every instance of every family and calculate the hidden line representation for each. Any time the view characteristics changed, it would have to repeat this. You can modify the pregenerated symbol by changing the cut plane in the plan view of the family file.

In the case of structural columns, the family contains a specific family property regulating whether Revit will use the pregenerated symbol or do a true cut of each instance. If you don't use slanted columns, you should let Revit show the family pre-cut.

[aaronrumple]

...and you'll find that setting under Settings > Family Category and Parameters > Show family pre-cut in plan views.

I think this is also related to a few bugs people have been reporting with architectural column graphics.

[robert.manna]

David, thanks for your reply.

Yes, I quite understand the neccessity of needing to take a "snap shot" of the family to reduce Hidden Line redraw and calculation. This is part of Revit's core functionality so it would hold true for all flavors, correct? I think that this "feature" should perhaps be clearly documented in the help, as I do not recall reading a description of that behavior in the help sections in the past.

Thank you,
-R

[aaronrumple]

It was one of those features that snuck into the program a couple of releases ago. I think Revit always did this - but it was something that was just recently exposed with more user control.

[twiceroadsfool]

Great thread! I never knew about the pre cut plan version, and its association to the family Cut plane...

[aaronrumple]

One note of caution. I made a family with two plan views with two different cut levels. That seems to have confused Revit. I did submit it to support, but they are still "looking at it".

[robert.manna]

David C,

Does the snapshot apply to elevation and or section views as well?

David B,

I appreciate your suggustion however while that is a good work around technique to apply on a project by project basis, I'm working on our corporate library, so I simply need to understand what is and isn't possible so that I can make appropriate decisions on how to build content.

Thanks for everyone's input,
-R

[aaronrumple]

No - elevations and sections have to be generated as you could be looking from many different angles...

[dbaldacchino]

When David Conant replies, that means....shut up and listen :)

I honestly couldn't make the connection at first since you didn't make reference to the casework family question, but then I figured it out. Please see attached example.

It seems that casework families don't respect the project cut plane at all. If the cut plane in the project crosses the family, then it displays per the plan view in the family (it seems to respect the last view created). Once the cut plane in the project doesn't cross it, then it displays as projected or beyond, depending on it's position in relation to the view range. If the plan view in the family has a cut plane that doesn't cross the family, then it will always show projected, regardless of the project cut plane. I'm going to draw a similarity to ADT here; this behavior is similar to when you have a wall style in ADT and you set it to always show cut at 4'-6" for example, regardless of the project cut plane (thus ignoring the project cut plane). This is not the exact behavior in Revit, since when not cut in the project, it will show projected instead.

In contrast, Generic Model families always seem to respect the project cut plane, regardless of what is shown in the family. Now if all families could be like this :) Perhaps that's why these are my favorite family type! It's very important that this behavior gets properly documented (I'll check if this was added to RAC2008 and post in the appropriate forum if not). I know that if I didn't come across this thread and DC wasn't so kind to point it out, I would have been one flustered user in a few weeks when I start tackling casework families!!

As to the original question regarding walls, the Revit help states that walls shorter than 6' are not cut, even if they intersect the cut plane. Also, I found this statement quite interesting:

There are a few categories for which an element located above the cut plane but partially below the top clip is shown in plan. These categories include windows, casework, and generic model. These objects are shown as viewed from above.

[robert.manna]

Thanks David,

Yes, the real question was about the behavior of families (specifically casework) not the wall behavior. Thanks for the info though on walls :). Bringing up walls was a means to illustrate the issue, and also I wanted to know if the two behaviors were related in some way.

For the record what DC had to say worked, when I manipulated the cut plane of the plan view in the family the casework behaved as expected. What I did find though was that casework will still ignore a plan region's cut plane setting, and instead will continue to respect the primary cut plane of the view (I don't know if this should be filed with support or not, is it a bug or intentional feature....?).

Regarding overhead casework, I've also started playing with that. Yes, you are correct overhead casework will show up in your plan view in the "full monty" (so to speak). Which of course is not the behavior that most of us are probably looking for. However I've been able to resolve the issue of how overhead casework is diplayed with the use of symbolic geometry and visibility settings (casework visibility settings give you the additional control of geometry's visibility based on if the family is cut or not).

Just as an FYI our overhead casework is designed as not hosted, and instead is set to be workplane based.

Prior to posting to AUGI I did test in RAC '08 to see if the visibility issues were the same, and they were. So therefore I expect these current families to transfer to RAC '08 without any problems. Have not done very much symbolic work in these current casework families as I will probably develop that in RAC '08 to take advanatage of one of its new features.

HTH,
-R

[ford347]

First off, thank-you Robert for starting this thread. I am getting a lot out of this. The view range in relation to how some families and walls show has always left me a little confused. For example, I have been boggled with the wall not cutting below 6' for quite some time. This one actually is a nice feature as it takes care of plan representation on it's own, but has driven me crazy before because there are times where I want to see some finish layers on a short wall during design, but cannot. So Thanks for the tip on that one Aaron!


Robert, what is your reason for creating your upper casework workplane based rather than wall based. We are trying to focus on our content library more and more and we are finding our biggest challenge is starting off on the right foot, which is pretty difficult when it's your first time creating certain kinds of content. Just trying to minimize 're-builds'.

Thanks.
Josh

[aaronrumple]

In contrast, Generic Model families always seem to respect the project cut plane, regardless of what is shown in the family. Now if all families could be like this :) Perhaps that's why these are my favorite family type!


I know that doors and windows use the plan cut from the family as I typically build my sashes on the floor with a 2' cut and then nest them into a window family with a sill and head height.

[aaronrumple]

Robert, what is your reason for creating your upper casework workplane based rather than wall based. We are trying to focus on our content library more and more and we are finding our biggest challenge is starting off on the right foot, which is pretty difficult when it's your first time creating certain kinds of content. Just trying to minimize 're-builds'.

Thanks.
Josh
I rarely build anything as wall hosted first time out. If things are going to be in a group - I might not want walls in the group. This allows me to make a full toilet stall layout as a group and place it in the design without worrying about the walls. I can always align/lock the objects to the wall if I want them to be constrained. If I later do need something that is wall hosted - I can nest the non-hosted object in a wall hosted family. This eliminates a lot of the confusing constraints you need to get geometry to all move together with the wall thickness.

The things I do build as wall hosted are those that will only be in a wall such as decorative elevation objects.

[radu.grosu]

Very nice thread. It's a pitty Revit does not go so deep with the documentation.

[robert.manna]

Agree with Aaron.

The general rule of thumb that I Iearned on my own, and have seen repeated by others is the only content that should actually be built as "hosted" is content that must interact with the host by cutting it. If not (especially with the addition of "work plane-based") you can create non-hosted content that one way or another you can "stick" to faces. The other nice thing about non-hosted content is that you can use it accross linked files, "work plane-based" and "face based" content should respected the "planes" defined by surfaces in linked models, such that the objects will move with the linked geometry. Face based families allow you to interact with the "hosting" object if needed. However they will only cut "host families" like walls, floors, ceilings, roofs, etc.

HTH,
-R

[Calvn_Swing]

We're working on a pretty complex facade, and to eliminate the need for some nasty stacked walls we've built a few window families that include cast stone sills and soldier course headers. Since this is a two story building with a cast stone element between the windows, I was planning on then nesting both window families into a host family that included some elements to take care of the infill.

We ran into problems with one of the windows already when we were making foundation plans. We wanted to cut through the cast stone sill and show that in the foundation plans, but we never could. We gave up on that strategy as a result, and went with stacked walls (which really suck by the way).

So, (I'd check myself but I'm not at work today)

Q1: Can you change this behavior in the Family Categories for windows as well, or did that only apply to columns? (The cut in project override)

Q2: How does this work with Nested Families? Does each nested family cut at its internal reference plane height, and then the host family cuts at its reference plane height? Or do all the families cut at the host family height? (not sure either is a good thing for us.)

Q3: Does this behavior differ if a family is only nested as opposed to shared and nested?

Q4: Is there a way to give a family multiple cut heights from different views? (much like reference linked view in host project files?) I take it from Aaron's comment that it isn't.

Thanks, and thanks again...