topic Re: Plaster pattern on a barrel vaulted ceiling in Modeling

Plaster pattern on a barrel vaulted ceiling

Erich — Fri, 10 Dec 2010 23:57:17 GMT

Does anyone have a good method for modeling a plaster pattern on an elliptical vaulted ceiling?

I considered using a complex profile and a curved wall but the profile would merely be extruded along the curve not normal to it.

I could do it with GDL, but since there isn't a command to allow for a bprism with multiple radii, the maths would get a bit harry.

Thoughts?

Re: Plaster pattern on a barrel vaulted ceiling

Dwight — Sat, 11 Dec 2010 01:00:46 GMT

I suggest:

Make the vault with a complex profile wall.

Make the detailing pattern as a slab that intersects with the entire arch. [deep enough to extend the vertical distance of the arch]

Create a second, inner arch as a complex profile wall that is exactly the plaster pattern trim depth inside the initial arch. [By reducing the perimeter of the initial arch definition fill.]

Solid Element Operation subtract the descending part of the plaster pattern slab with the inner arch.

Solid Element Operation subtract with upward from the outer arch.

Re: Plaster pattern on a barrel vaulted ceiling

Dwight — Sat, 11 Dec 2010 04:47:17 GMT

Enough, already, with the cheap and nasty!

Assuming those parts are painted wood, you could model each component as a tilted beam or column to match each local slope. That's not so difficult since it has quadrilateral symmetry.

Re: Plaster pattern on a barrel vaulted ceiling

Erich — Sat, 11 Dec 2010 05:04:56 GMT

Dwight,

The cheap and nasty doesn't quite work for me. For it to be accurate, I would need to distort the pattern to match the plan projection at the arch bleah! .

Modeling piece by piece is an option, and perhaps one I will need to undertake. However, since the pattern is not yet fully settled, I am not certain I want to spend the time only to have to redo it later.

Since the pattern I show is based on the vault flattened out, I am considering sectioning it, sticking it into GDL and rotating each section. The vault itself is already a GDL object and I can get individual section angles from the faceting of the curves in the building section. I was just hoping for something a bit easier.

If only we could bend slabs as easily as we can bend walls....

Re: Plaster pattern on a barrel vaulted ceiling

Dwight — Sat, 11 Dec 2010 05:08:55 GMT

There's only a dozen unique parts - it can't be that hard to model.

Re: Plaster pattern on a barrel vaulted ceiling

Dwight — Sat, 11 Dec 2010 05:21:33 GMT

Modelling Wizard Ralph is asleep right now but tomorrow morning he will show the OBJECTIVE way to do it.

A real solution.

Re: Plaster pattern on a barrel vaulted ceiling

Anonymous — Sat, 11 Dec 2010 10:13:48 GMT

If the results don't have to be dead on it looks like it could be done by using Dwight's method but using profiled beams (and perhaps columns in the central part) instead of slabs to take the cuts out of the inner arch.

A relatively crude version could be done with a single beam profile for the lower part and a column for the center. For better resolution it could be done in narrower strips. A side benefit is that the columns and beams can do the cuts automatically by adjusting the priority settings. Not a big deal but it saves doing the explicit SEOs.

Attached is a quick example just using a single beam profile repeated and adjusted (sort of) to match the slope of the arch.

Re: Plaster pattern on a barrel vaulted ceiling

Ralph Wessel — Sat, 11 Dec 2010 15:08:26 GMT

Dwight wrote:
Modelling Wizard Ralph is asleep right now but tomorrow morning he will show the OBJECTIVE way to do it.
A real solution.

Thanks Dwight. Yes, OBJECTiVE provides an easy way to solve this. It does pretty much what you wanted, i.e. bending a slab to a curve. If you draw the shape you want with a slab (or fill) and make an Elevation profile with OBJECTiVE's profiling tools, it can be bent to a curve (optionally preserving its proportions). Refer to the attached image.

However, OBJECTiVE can only bend the shape to a s single curve and your ceiling is elliptical, so the solution takes a bit more work. I'll illustrate this in the next message.

Re: Plaster pattern on a barrel vaulted ceiling

Ralph Wessel — Sat, 11 Dec 2010 15:36:35 GMT

Dwight wrote:
Modelling Wizard Ralph is asleep right now but tomorrow morning he will show the OBJECTIVE way to do it.

To fit the profile to an elliptical ceiling using OBJECTiVE, do the following (referring to the attached image):

1. Draw the shape of the ceiling laid out flat (as you have already done) with a slab or fill.

2. The ceiling shape will have to be broken down into arcs (which approximate very closely to the elliptical shapes). I created a polyline of arc segments, then split the roof shape to the lengths of each arc in the segment.

3. Next make the fills/slabs into profiled objects. For each segment in turn, select it and click the menu OBJECTiVE > Component > New Profile. In the New Profile dialog set the profile type Elevation, enter a profile name, pick the library to store it in (Embedded is convenient), and a default thickness.

4. When you click OK, OBJECTiVE will prompt you to click two points indicating the bending axis (the direction of the plane the shape is bent in). In this case, it is straight across the ceiling profile. The new object is created after the second click.

5. When the new profiled objects have been created, open their settings and check the option to Keep proportions so the shape is not distorted as it is bent to a curve.

6. Now we need to tilt all the objects to an upright position (so we can look along their length). Select all the profiled objects and click the menu OBJECTiVE > Tools > Rotate. The rotation is much like ArchiCAD's 2D rotate - click the two points to the axis of rotation, then a third to set the rotation angle (you can enter the angle in Tracker too).

7. Now we take each object in turn and align it to its equivalent curve in the ceiling polyline. Move the object origin to the arc origin and rotate it so it passes through the arc end.

8. Then click the stretchable node on the profile and use it to bend to the arc curve.

9. The finished segments should look like this in 3D.

10. Then use OBJECTiVE > Tools > Rotate to tilt the objects back to the level plane again.

11. The finished ceiling in 3D.

Re: Plaster pattern on a barrel vaulted ceiling

Erich — Sat, 11 Dec 2010 15:52:14 GMT

Thanks all

I knew Objective would be able to deal with this, unfortunately the budget doesn't allow for it right now (sad isn't it). However, Ralph has given me a reasonable GDL solution. I can use a series of local curves and then use a series of bprisms set to these local curves. This will result in a minimal number of bprisms and a reasonably distortion free result. Revisions to the pattern would be fairly simple to accomplish merely requiring updating the coordinates for the bprism.

Mathew, I had not considered using profiled beams and Dwights method. That is a good thought and one I will keep in mind.

Re: Plaster pattern on a barrel vaulted ceiling

Karl Ottenstein — Sat, 11 Dec 2010 18:28:55 GMT

Very nice, Ralph. I encourage you to take this ... and so many of the other examples you have posted here on ac-talk ... and gather them in a blog on your Objective / Encina web site as they really augment the user manual in a very practical / visual way! (In addition to the examples on the actual Objective page.)

Cheers,
Karl

Re: Plaster pattern on a barrel vaulted ceiling

Anonymous — Sat, 11 Dec 2010 20:34:40 GMT

It's always a torture to see what objective can do
At least for the ones like me that cannot afford it. 🙂

PS: Very nice work!

Re: Plaster pattern on a barrel vaulted ceiling

Erich — Mon, 13 Dec 2010 02:50:47 GMT

OK for the body of knowledge that this forum represents, here is how I accomplished this.

1. Drew the shape of the ceiling laid out flat as a fill. (actually I used walls and then exploded them to create an outline for the fill).

2. Broke down the elliptical ceiling shape in the a series of smaller approximate arcs (Thanks Ralph!)

3. Determined the chord length of each approximate arc and then split the ceiling fill at that point.

4. Dragged the fills (there were multiple fills in most of the chord lengths) into one of the scripts other than the 3D script in the new GDL object to obtain the points for a prism.

5. In the 3D script I wrote a BPRISM command for each fill section. I used the radius of the approximate arc for that section as the radius for the BPRISM and then moved the new curved section of ceiling into location with an appropriate ROTx and ADD statements.

6. Next I changed the status code for the new BPRISM commands to 15 (some should really be 13 but I haven't done that yet) so they would show solid with their edges.

7. And here is the finished ceiling.

8. Edits are fairly simple now (As long as the vault doesn't change width) by just changing the fills and using them to get the new points for the BPRISM.

THIS WOULD BE MUCH EASIER WITH OBJECTIVE!

Re: Plaster pattern on a barrel vaulted ceiling

Anonymous — Mon, 13 Dec 2010 05:29:20 GMT

Karl wrote:
Very nice, Ralph. I encourage you to take this ... and so many of the other examples you have posted here on ac-talk ... and gather them in a blog on your Objective / Encina web site as they really augment the user manual in a very practical / visual way! (In addition to the examples on the actual Objective page.)

Cheers,
Karl

I would like to second that!
For guys like me with no GDL capibilities, Objective rules.
Now 3/4s of the way to finishing up my first major remodel job using Objective, and can't imagine AC without it.

Re: Plaster pattern on a barrel vaulted ceiling

vistasp — Mon, 13 Dec 2010 10:32:20 GMT

Erich wrote:
THIS WOULD BE MUCH EASIER WITH OBJECTIVE!

lec1212 wrote:
Now 3/4s of the way to finishing up my first major remodel job using Objective, and can't imagine AC without it.

C'mon GS, make Ralph an offer he can't refuse!

Re: Plaster pattern on a barrel vaulted ceiling

Rod Jurich — Mon, 13 Dec 2010 12:25:44 GMT

vistasp wrote:
/.
C'mon GS, make Ralph an offer he can't refuse!

Sorry to disagree vistasp, let Ralph be free to continue his excellent work.
Not to say GS would not honour his contribution. Just how many innovative
and excellent takeovers go sour. I'd hate to see my investment go that way.
Besides his fee is not excessive rather very reasonable considering what it achieves.
Best of all students, have it free of charge.

Re: Plaster pattern on a barrel vaulted ceiling

vistasp — Mon, 13 Dec 2010 13:03:14 GMT

Rod wrote:
vistasp wrote:
C'mon GS, make Ralph an offer he can't refuse!
Sorry to disagree vistasp, let Ralph be free to continue his excellent work. Not to say GS would not honour his contribution. Just how many innovative and excellent takeovers go sour. I'd hate to see my investment go that way. Besides his fee is not excessive rather very reasonable considering what it achieves.
Best of all students, have it free of charge.

You have some very valid points there, Rod. But, that what sounds like a reasonable fee in North America/Western Europe/ANZ is much less so in some other parts of the world. If you consider purchasing power parity as opposed to plain currency conversion, Objective would cost me the equivalent of US$ 900 instead of US$ 300.

Re: Plaster pattern on a barrel vaulted ceiling

Rod Jurich — Mon, 13 Dec 2010 23:03:14 GMT

vistasp wrote:
/.......If you consider purchasing power parity as opposed to plain currency conversion,
Objective would cost me the equivalent of US$ 900 instead of US$ 300.

I appreciate more now you explain an even more valid point about exchange rates/purchasing power.
The way the US economy is going you may have parity soon
You should talk to Ralph. As my father says "if you do not ask, you will never know"

Re: Plaster pattern on a barrel vaulted ceiling

Dwight — Tue, 14 Dec 2010 00:07:21 GMT

Without trying to sound like an angry idiot, my initial reaction was:

"Yeah, that's rough. OBJECTIVE, and my book and all of the other Archicad add-ons seem expensive for our colleagues in India, but those of us who live in the Western world have to make a living, too, now that the international electronically-connected world pursues basic rendering and drafting jobs for a fraction of our billing rates. [According the the weekly promotions I receive in my email]"

You can't afford add-ons and I can't heat my house [for example].

OBJECTIVE is a totally unique and powerful tool that pays itself overandover compensating for Archicad's horrific modeling deficiencies, unlike my books, say, where you could use time [like i did] to discover these things for yourself.

Even at the equivalent of $900. how many billing hours can you save in a year to pay for OBJECTIVE? Perhaps we should all invoice Graphisoft for those functions that SHOULD HAVE COME WITH THE BASIC LICENSE!!!!!!!!!!!!!!!!!!!!!!!!

Thank you, Ralph. At any price.

Re: Plaster pattern on a barrel vaulted ceiling

Gerald Hoffman — Tue, 14 Dec 2010 00:52:21 GMT

I'd like to echo Dwight here and also add that I have had OBJECTiVE for several versions of AC now and unlike a lot of other Add-ons he has not to date charged for updates. I'm not suggesting Ralph that you should but only letting others know what value there is in your add-on. I use it on every project I do and find it the best tool in the box in its simplicity and usefulness!

Cheers,