topic Re: Ellipsoid stairs? in Modeling

Ellipsoid stairs?

Anonymous — Thu, 25 May 2023 14:50:25 GMT

Is there any way to design a stair that follows an ellipsoid profile as opposed to a circular one?

Re: Ellipsoid stairs?

Anonymous — Sat, 24 Mar 2012 09:38:08 GMT

Yes, it could be done. But the result is somewhat impredictable (see the picture).

Re: Ellipsoid stairs?

Anonymous — Sat, 24 Mar 2012 10:04:10 GMT

Thanks andro55; I believe that you used multiple circular stairs. I was looking at something more straightforward like a single stair having an ellipsoidal path. Regards.

Re: Ellipsoid stairs?

TMA_80 — Sat, 24 Mar 2012 11:03:51 GMT

have you tried a custom stair creation ( maybe that's what andro55 have done )
have a look in thearchicad help

ArchiStair ( Cigraph ) or Stairbuilder ( Cadimage) would be other options to consider...

At a last resort, built it manually... though, not a parametric solution

Re: Ellipsoid stairs?

Anonymous — Sat, 24 Mar 2012 11:11:16 GMT

NO.
I used only a Fill for stairs outline and multi segment Arc for the line of travel.
You must use menu Design > Create Stair Using Selection!!

Re: Ellipsoid stairs?

TMA_80 — Sat, 24 Mar 2012 11:26:56 GMT

That's what I meant by custom stair...

Re: Ellipsoid stairs?

Karl Ottenstein — Sun, 25 Mar 2012 17:19:47 GMT

I got slightly better results with the Create Stair Using Selection, perhaps because I offset the first ellipsoidal segment to make the stairs the same width, and also to define the line of travel.

Still, as you can see here and in the next post with 3D, one tread is smaller than the others and the hand rail is odd at that same point.

The ArchiCAD custom stair has no features for subsequent editing / correction - no hotspots in 2d or 3d. ArchiStair 2, on the other hand, has hotspots on every single tread, allowing you to fine-tune how you want everything built. (The initial appearance of the treads for this same ellipse was a little weird for me - but the hotspots let me correct things.)

Karl

Re: Ellipsoid stairs?

Karl Ottenstein — Sun, 25 Mar 2012 17:21:06 GMT

Here's the 3D from ArchiCAD...

Re: Ellipsoid stairs?

Anonymous — Thu, 29 Mar 2012 03:25:34 GMT

Thanks andro55, TMA_80 and Karl. I think I will also look at Cadimage to see if they provide a parametric solution.

Re: Ellipsoid stairs?

Anonymous — Mon, 30 Jul 2012 07:07:14 GMT

Hi,

I tried following the Help instructions on Creating Stair from Selection and I just got an error that says: "Cannot generate stair with this line of travel."

I did offset the arc from the side of the fill to serve as my Line of Travel and got this message.

When I tried to use a straight line as Line of Travel it seemed to work. However, I want a curved path similar to what you've shown in your screenshots. I'm currently using AC15 (unboxed 16 but haven't properly migrated yet).

Is there something I'm doing wrong? A setting perhaps? Hope somebody can help me out.

Re: Ellipsoid stairs?

Erika Epstein — Mon, 30 Jul 2012 14:43:21 GMT

Archicad's stair tool incorrectly breaks the ellipse into arc segments based on a circle. I've submitted bug reports on this, and still no solution. Interestingly, even GS's manual shows the bad results 🙂

Re: Ellipsoid stairs?

Anonymous — Mon, 30 Jul 2012 16:14:53 GMT

Erika wrote:
Archicad's stair tool incorrectly breaks the ellipse into arc segments based on a circle. I've submitted bug reports on this, and still no solution. Interestingly, even GS's manual shows the bad results 🙂

Do you mean that it does it badly? True ellipses are not supported in any of the standard elements or GDL statements so approximation by arcs is to be expected. AFAIK the only alternative would be custom GDL code or primitives.

Re: Ellipsoid stairs?

Erika Epstein — Mon, 30 Jul 2012 21:44:44 GMT

Matthew, it breaks the line of the 'ellipse' or 'oval' into segments of a circle's arc. Each time there is a new segment of arc, it starts with a new tread, truncating the last tread of the previous arc segment.

AC will break any line of a stair into arcs and straight lines and each section of arc or line will start with a new tread.