curved floors in 3d

[lucylou]

hi. this is quite hard to explain so bear with me!!!

we have 'oval' / elipse shaped floors (created from the floor command) that are perfectly oval when in 2d however when they are in 3d either in the viewport or even in the design layer they have straight(er) edges... like a hexagon?! im sure there is a way to fix this but not sure how. please help! )

[mike m oz]

VectorWorks Preferences/3D/3D Conversion res. The higher it is set the less faceted the oval floor will be. To get it to redraw double click on the floor to go to the 2D shape. Don't do anything - just exit by clicking the Done button.

[lucylou]

Thanks mike.

i had tried the 3d Conversion Res thing however nothing happened. i am now aware of the secret way of making it work byt clicking into the object!!!1

thanks very much )

[Petri]

Why do I think this is controlled by 2D conversion resolution? The oval ('ellipse')* is first converted into a polygon with 2D resolution, then the polygon is extruded.

Check 2D conversion. If it not "High", redo the thing. The original oval does reside inside the floor.

*) The VW oval is an ellipse only in the Netherlands and perhaps some other mathematically-challenged countries. The Dutch ignoramuses (which is not analogic to Dutch treats or Dutch courage) defend their position by calling those who understand mathematics "deluded". They'd make great medieval Popes and Grand Inquisitors, those Dutchmen!

[panthony]

The ellipse has finally come out of the closet. And to think we've know it as an oval for all these years. Next thing you know we'll find out that all circles are irrational in circumference.

[Petri]

Maybe "NC" is a mathematically challenged country, too?

[propstuff]

I just love discussions of etymology and semantics and archaic and colloquial uses of words. (no, really, I do)

Oval means "egg shaped"

"......approximately egg shaped, ellipsoidal............having more or less the shape or outline of an elongated circle or ellipse...." ; Oxford English Dictionary.

So an Ellipse is an Oval, but an Oval is only possibly an Ellipse. :-)

.............And of course, the "Oval tool in VW draws only Ellipses, rather than the infinite variety of Ovals of any given size. ;-)

All of which goes nowhere to explaining why the "3D resolution" setting does not actually effect the 3D resolution of VW Ellipses......

[Petri]

Semantics & etymology are indeed fun, but the VW "ellipse" is a "squashed circle", not "the set of all points (x, y) in the plane such that the sum of the distances from (x, y) to two fixed points (foci) is some constant."

Why? Well, because neither Apple's nor Microsoft's graphics libraries use true ellipses.

[propstuff]

Why? Well, because neither Apple's nor Microsoft's graphics libraries use true ellipses.

Curious. You'd think 2 nails and a piece of string would be easy enough to program.

I also would have thought this would be defined by the NNA engineers coding rather than the OS graphics library? Oh well.....

Post script:

I just did a quick draw and measure of 3 randomly drawn ellipses, and VW "Ovals" do indeed seem to be true Ellipses on the basis of my brief test.

Personaly, I've always pictured "Ovals" as being egg shaped like general domestic fowl eggs. IE (to use the mathenatically correct term) "fatter" at one end than the other.

but that's just me. :-)

Edited October 19, 2007 by propstuff

[Petri]

I just did a quick draw and measure of 3 randomly drawn ellipses, and VW "Ovals" do indeed seem to be true Ellipses on the basis of my brief test.

They may seem to be, but a squashed circle is not the same as a conic section. Measuring this would be difficult because you can't establish where the foci would be if the oval would be an ellipse.

[propstuff]

Well all I did was draw a few whatevertheyares at random, locate the foci in the traditional way, and drew about 6 sets of 3 vertex polygons from the foci to a random point on the circumference.

In every case the polygons' perimeters were the same length for each ellipse (and the same length as the major axis as expected).

That, as you pointed out, is the definition of an ellipse.

I might have just chosen 3 "squashed circles" at random which happened to behave exactly like ellipses, but they seem to quack like a duck as far as I can see.

N.

[Petri]

In every case the polygons' perimeters were the same length for each ellipse (and the same length as the major axis as expected).

That, as you pointed out, is the definition of an ellipse.

No, that's not the definition.

[propstuff]

In every case the polygons' perimeters were the same length for each ellipse (and the same length as the major axis as expected).

"the set of all points (x, y) in the plane such that the sum of the distances from (x, y) to two fixed points (foci) is some constant."

So I drew a polygon from one focus to a point on the ellipse and then to the second focus,... and the length remained the same regardless of the location of the point on the circumference. How would that be different from "the sum of the distances from (x, y) to two fixed points (foci) is some constant."

BTW the "some constant" is always the length off the major axis (as it must be)

[Petri]

I'm not saying that the difference would be big, but the "flatter" the shapes, the bigger it gets. May well be below measurement accuracy in most cases, but the maths is different and the squashed circle is not an ellipse.