measure distance along curve

[Anonymous]

How do you measure the distance along an arc? I'm trying to place windows in a curved wall where I am given the distance from center to center of window measured along the curve.

If I set my origin to the radius of the curve, I could do it, but I would need to know the angle.

Thanks,

Jason

[Link]

Jason

Can't you just draw a construction circle? That's what I'd do - draw a circle with the radius set to the distance between the center of the windows and put the origin at the center of one window, then place the center of the next window where the construction circle meets the curved wall.

Clear as mud? If so, let me know and I'll attach a screenshot.

Cheers,
Link.

[Anonymous]

Link,

Your method produces the chord length and not the circumferential. In cases of small arcs this probably doesn't matter but I would always feel better to calculate the angle.

The formula is a = (d*57.2958)/r where a is the angle we are looking for, d is the measured circumferential length, 57.2958 is the number of degrees in a radian (180/pi), and r is the radius.

NO WAIT! I just had an idea. Yes it works!

In the control palette, set it to detect points by distance and ArchiCAD will give you the tick marks around the perimeter. If the lengths vary you will have to type in each new value and split or intersect the arc, but this is still probably quicker than repeated trips to the calculator.

[Link]

You're absolutely right. Sorry for the dodgey advice.

Set the 'Snap Point' distance to the desired radius and you'll be set.

Cheers,
Link.

[Djordje]

Link wrote:
Set the 'Snap Point' distance to the desired radius and you'll be set.

... and if you want to dimension, there is the curved dimensioning line!