Parabolic Curve

[Roger Evans]

How would you go about establishing a Parabolic Curve within Revit?

Lines / Walls / Roofs / Profiles

[jwilhelm]

http://www.pen.k12.va.us/Div/Winchester/jhhs/math/lessons/calculus/parab.html

this link shows a way to construct one with a series of lines&circles
you could use this method, a bit tedius though

[aggockel50321]

Here's a parabola tool I made up, based on a method I found here. (http://www.du.edu/%7Ejcalvert/math/parabola.htm)
(had to work today & am bored)

Load it into your project & place it with the componet tool. Adjust the width & height parameters. The base of the triangle, the lowest intersecting lines, and the midpoint of the center of the triangle comprise the locus of points to generate the parabola. (see above link for further explanation)

If you want to creat a wall, do an in-place wall family (wall command doesn't support spline tool), make an in-place sweep. When creating the 2d path, use the spline, and select the points listed above (7 total (see jpg)

When complete, you can either delete the tool, or turn it off. It's a generic model, & the lines are a subcategory called parabola.

[mmodernc]

or using massing family created in place. solid cone minus void cube.pick prabola to create wall.

[Joef]

We have some very clever people 'round here! That is a nifty solution.

[Roger Evans]

Thanks for the replies guys ~ I was half expecting some kind of formula that could be applied ~ I found this

Parabola ~ locus of a point which moves so is equidistant from a fixed point (called the focus) & a fixed line (the directrix) is called a parabola
Any equation of the form y=ax2+bx+c
or y 2=4ax will give a parabolic shape
The path of a projectile is approximately parabolic
(NB read the 2's above as squared)



For my part what I would like ~ (because it would be a lot simpler for me to do)~ is some form of additional optional choice in the arc tool to choose this line as true arc / catenary / parabolic / hyperbolic etc etc

[Wes Macaulay]

or using massing family created in place. solid cone minus void cube.pick prabola to create wall.This would be the mathematically correct way. Thanks for that!

I don't know that many CAD programs used in architecture provide true parabolic drafting tools.

[Roger Evans]

I realise it's Not an every day requirement Wes ~ maybe once in a lifetime architecturally~ but I thought it would have to be in Inventor and be more commonly used for product design