topic Dome despair in Modeling

Dome despair

Bruce — Tue, 23 May 2023 13:20:18 GMT

I have a dome to model that is based on the proportions of the inner dome at St Pauls cathedral, London. It's fairly simple in geometrical terms, but ArchiCAD can't handle it.

It's basically a semi-circular dome, except the arc (in section) centre point is offset from the centre of the dome.

I am getting ready to tear my hair out. I have tried:
- Dome roof builder: it only does semi-circular domes
- Mesh to Roof: I can't get proper thicknesses and joining to happen
- SketchUp import: I can get it in, but then it malfunctions
- DWG object import: don't know how
- Profiler tool: does not play the game - after about 10 attempts I gave it up as a bad joke
- Cadimage profiler: will only save profile on workstation, I have to share this project. Crashed on first attempt anyway.
- No, I do not have Maxonform.

I am at my wit's end. Can anybody help?

Re: Dome despair

Anonymous — Mon, 26 Mar 2007 05:54:23 GMT

Are you familiar with GDL language?

I'm not sure how your dome will look like, but I'm almost sure that it could be done in GDL rather easy.

Could you draw some section of the dome and also a orthogonal 3d picture of it.

Re: Dome despair

Anonymous — Mon, 26 Mar 2007 07:22:20 GMT

I assume you mean that it is elliptical in section. This would be quite simple in GDL. You can also make a reasonable facsimile by lofting a curved roof, cutting it to a pie shape and rotating copies. Unfortunately anything you do with roofs will be faceted. The only way to avoid that is with GDL.

Re: Dome despair

Bruce — Mon, 26 Mar 2007 20:10:11 GMT

No, I don't know GDL...it's on my 'to do' list. At the moment it's just gobbledegook.

I've attached a section showing the setout of the dome. It's circular in plan.

Re: Dome despair

Dwight — Mon, 26 Mar 2007 21:27:29 GMT

Youse!

This looks like a job for Super…Profiler.
Or the custom profile as a beam with short segments.

The way you described it at first was that the opening would be off-center. That would be a trick!

Re: Dome despair

Bruce — Tue, 27 Mar 2007 03:07:19 GMT

Sorry Dwight, I'm not sure what you mean.

I've tried the profiler (the goodies one) but can't get it to do the job properly.

Also I can't figure out what you mean by a complex profile used with a beam.

Re: Dome despair

Dwight — Tue, 27 Mar 2007 03:23:36 GMT

Do you need a tutorial on using Profiler? Custom Profile? I'm sorry to not be inclined to write an essay tonite.

but here are hints:
- always draw your shape in the positive quadrant: upper right hand side relative to your spin point.

- mouse control - Realize that the spin cannot spin on itself - you must place a tiny hole in the end of your spin with the smallest dsplacement from the center of the revolve.

It can't be explained with words, but it can be demonstrated in seconds. It's a trick!

As for a custom profile: Make a custom profile for the side of your dome. Assign it to work with beams. Draw your circle for the base of the shape, Set magic wand to a short linear length. Magic wand the beam into the circle. Viola.

Re: Dome despair

Anonymous — Tue, 27 Mar 2007 03:51:24 GMT

This may help.
see attached

Re: Dome despair

Bruce — Tue, 27 Mar 2007 04:07:19 GMT

Peter - thanks for that, but I had already read that.
Dwight - thanks for your help - glad Profiler works ok for you. I won't be recommending it though.

Re: Dome despair

Dwight — Tue, 27 Mar 2007 04:12:03 GMT

Well, i never said it worked okay.
Barely.

What i would say is that it works okay once you know the tricks and manage to remember them each time.