Cutting a curved roof

[DanielleAnderson]

A train station I recently modelled required a complex roof shape that just happened to be curved at the same time--imagine a sort of kidney shaped roof with a gentle curve to it.
I used the roof by extrusion tool and drew the curve of the roof and then extruded it the full distance. Then I chose to cut the roof in plan. It took me quite a while to get the shape just right and I made sure that all the lines connected continuously, etc. and when I hit the finish roof button, I got an error that said simply "the roof could not be cut." If I chose to hit cancel and try to redraw the roof, I always got the same answer. The only ways around it that I found were 1) Back totally out of the roof cut and start over again (grr) and cross my fingers that it might work on the second or third try or 2) Flatten the roof profile shape and if I flattened it just enough, it worked.
It was nice that I found a work-around, but the final product wasn't quite what we were looking for because for some reason Revit thought that roof shape was not possible to create--we've done similar station roofs elsewhere that have actually been constructed in the physical realm so we know it's possible.
Is there a better way to create a roof so that Revit is more flexible about what it will allow?

[Scott D Davis]

Draw the roof by extrusion to get the curve in elevation you desire first. Let the extrusion be larger than your building footprint. Then create an in place family void that is a rectangle with a hole in it the shape of the 'kidney' you want, and use it to cut the extruded roof profile.

Look at some of the pictures I posted in the gallery, this roof was similar to what you are trying in that it curved in elevation, and the walls were curved in plan.

Here's an example I did quickly to show you, too:

[Scott D Davis]

Ok, I'm a bit :screwy: ? I read your post the first time, and responded, and now when I read it again, I answered with exactly what you had already tried! Sorry!

I think the key to selecting the curved walls for the void-cut, is to use the TAB key to select the whole chain of walls at once.

Maybe you could post a piece of yur model and roof, and I can try and help figure out where the error is coming from.

[PeterJ]

Until it is figured out can you achieve what you want with a void in an in-place family to cut the roof?

[DanielleAnderson]

Okay, I've uploaded a little piece of the roof so you can see what is going on. I think the roof is a little more complicated than the above example...

[Scott D Davis]

It's hard to tell because your image is a little small, but is your roof 'saddle' shaped, in that its a barrel in one direction, and then flares up at the ends? If you can cut-n-paste your roof by itself into a new RVT, then post it, that might help.

You are on the right track, it seems. My example was quickly done, and I know it wasn't very complicated, I was trying to reproduce your description: a arched roof in a kidney shape.

[DanielleAnderson]

Try this one, it is just the isolated roof. What we wanted to achieve was a deeper barrel and a more dynamic cut-out shape.

[Scott D Davis]

So I understand: You used the "Cut Plan Profile" button, to cut out the shape of the roof? This particular tool is more effectively used to cut a hole or piece from a roof, not to cut out the geometry all the way around. The examples I posted, I used an in-place family void, of the Roof catagory, and used the the Cut Geometry to cut the barreled roof into the shape I wanted.

Try that and let me know if it works. If you need help with in-place family voids and cuts, let me know, too! (but by the looks of it, you already know how!)

[aggockel50321]

Try creating the whole roof as an in-place family, & do all your solids & voids within the family. I've had better luck that way.

PS: Tell JRT i said hi.

[DanielleAnderson]

Said hi to James...
Yes, I need to experiment more with in-place families. I think that is the way to go for many things. Are in-place families comfortable touching? I've noticed occassionally massed objects like to have a small gap in between elements.

[Scott D Davis]

No gaps that I know about. Here's a very rough approximation of your example, made with an extruded roof for the barrel, and an in-place family void to cut the shape.

[Architeria]

I thought I'd resurrect this thread because it seems to be giving me what I'm looking for although I haven't tried it yet.

But it occurred to me that since it's been some three years since this discussion that later versions of Revit may have changed the approach somewhat. I'm using 9.0 but am also curious if '08 has provided new tools that affect the methodology.

Thanks


GO GATORS!!

[dbaldacchino]

Nope, not really. Still the same methodology. Revit uses the idea of "solid interacting with void" a lot in modeling, and it is quite powerful in fact. You can use in-place voids to "demo" portions of roofs or to cut out more complex shapes. One thing I've come across when using this technique is that I was frequently getting a "circular chain of references" error, and I was not able to finish the sketch. It took me a while to figure out what was going on, but then I traced it to some existing walls that had their top attached to an existing roof that I was trying to "demo" with this void. So I had to detach those walls first before I could create my void cut.

Another editing issue I came across in a phased project is that if your roof is in a different phase than your void (EX: roof is Existing and in-place void is New Construction), you cannot select the in-place void to re-edit it. It simply won't select! You have to set your roof's phase temporarily to match that of your in-place family (New Construction in this example) and then your void is selectable. Once you're done editing, change your phasing back to what it needs to be (roof changed back to Existing in this example).

[Architeria]

Thanks, David. Unfortunately, I'm stumped.

I drew some walls and added an arched roof by extrusion then created a void extrusion using the massing tools but kept getting an error message saying that there was no solid geometry to cut.

So then I thought maybe I should create the roof as a solid mass so I did that but ended up getting the same message. I did move the roof so it was no longer touching the walls but that didn't change anything. The only thing I can think of is that I'm using the wrong tools and that there is a void form available somewhere other than massing that I haven't been able to find.

Any advice would be greatly appreciated.

Thanks

Philip

[Scott D Davis]

Masses are meant for Massing a building, not creating building components such as roofs, or voids to cut roofs. Think Massing Studies, not objects.

To create components, use In Place Families, and then you can make combinations of Solids and Voids in the proper category. Click on Component, then select Create In Place from the Options Bar. Make an extrusion for the roof, and then create a void whiile still in Family mode to cut out the shape. When done adding all the solids and voids you need, then Finish the Family.

If the roof was created by a "Roof by extrusion" in the Roof tool Flyout from the Design bar, then you can simply selected the roof, and choose Cut Plan Profile from the options bar. This takes you to sketch mode, where you sketch the shape to be cut out. Then Finish the sketch.

[Dimitri Harvalias]

Philip,

Don't use the massing tools to create your void. From the modeling menu select Create from the bottom of the list to create your cutting form. Then use the Cut Geometry tool to carve the extruded roof.

Scott beat me to it!
One point about using the cut plan profile is that it will only create a plumb cut through your roof. Using void in place families allows you a little more control over how you shape the roof form.

[dbaldacchino]

You guys described it perfectly. What seems a bit "abstract" to users that have never done this is that Revit allows you to create a component using a system family (such as a wall or a roof) but then it also allows you to create an in-place family of the same category (wall or roof for example) that contain voids only, and will let you use Cut Geometry between the two different families of the same category to create complex carved objects.

[Architeria]

Thank you gentlemen, and on Mother's Day, no less.

Although the first few times I wasn't able to select the Roof Form with the Cut Geometry tool, I eventually got it to work and I thank you for the instructions. I plan to practice it until it seems second nature. Although it is abstract and I wish it were more intuitive, I do understand the concept, it's mastering the protocol that will take some time for me. I also confess to having trouble with some of the terminology. Components, I understand. Cut Geometry makes sense. But I thought In-Place Families referred to the clients who refused to move out while you're adding a second floor to their house.

I notice that the dialogue on my new Lichtenstein avatar is illegible; rats! It says, "M-MAYBE HE BECAME ILL AND COULDN'T LEAVE THE STUDIO!" It seemed germane somehow.

Thank you again for all your help and patience.

Philip

[dbaldacchino]

...and on Mother's Day, no less....
That could be the definition of a geek ;)

[Dimitri Harvalias]

That could be the definition of a geek ;)I'll have you know Dave, I was sitting in my kitchen, feeding my grandaughter breakfast while my daughter was at school and my wife was still in bed sleeping while I answered that post. I figure I managed to score a few brownie points from both moms in the house while still being productive.
And my wife says men can't multi-task !:lol:

[dfriesen]

... my grandaughter ...That kind of blows my mind, that you're a grandpa - aren't you about my age?? Then the realization sinks in - I'm old enough to be a grandpa too... yikes.