# Brückenmodul

I apologize for the simplicity of this question:
How can I use Rhino or Grasshopper to calculate a 3D curve from a curve in the XY plane and a curve in the YZ plane? Maximum deviation of 1mm.

Or to put it more simply: How can I get the coordinates from the point of intersection of any line (e.g. YZ curve) through any planes (e.g. every 1 meter in the y direction)?

Can you specify with a simple sketch a bit better what you are trying to get as an output. But I am 99.9% sure you can do what you want with Grasshopper.

When you say “3D curve” do you mean a curve or a surface? Or do you mean an interpolation between both curves?

To get intersections you would normally draw some lines, say spaced apart 1m in Y and then get the intersections of both curves using “Curve | Curve” from the intersection tab of Grasshopper.

But yeah, show us what you roughly want to get and then I think its super easy to build in GH. Oh an attach your Rhino file with the curves or internalise them in a Grasshopper file.

ps: from your name I assume you are in Zurich, CH. So am I

1. Divide both curves by the same number of points.

2. Deconstruct both sets of points. (to get the X, Y and Z coordinates of each point)

3. Construct new points using X and Y from one curve and Z from the other curve.

4. Feed the new points to Interpolate curve.

I’m also not sure exactly what you are looking to do, but maybe this will give you a starting point.

Brückenmodul.gh (6.8 KB)

p.s. I’m also in Zürich!

It’s a classic method for generating the sheer line of a boat hull based on one planar curve from top view and a second planar curve from profile (side) view.

P.S. Using your curves, the method I suggested gives a different result:

Brückenmodul_2021_Jul29a.gh (6.8 KB)

P.P.S. Come to think of it… your method of intersecting the extruded curves is more accurate!

I’ve also used plane intersections with both curves to make sure each pair of points has the same X coordinate.

Thank you for the opportunities.
The division of the entire curve is too imprecise for our planning technology. Armin Selz’s solution is what I was actually looking for. Only a new problem arose:

When I have now calculated the points on the curve of the height, they are all without metering (see panel). How can I organize the output according to the panel so that a curve can be generated from it?

@Armin Selz
Danke für die Lösung, genau sowas suchte ich. Doch wie kann ich nun die so errechneten Punkte umformen, damit es mit der horizontalen Absteckung kongruent ist und somit zur 3D-Kurve verbunden werden kann? Weisst du hierbei auch Rat?
Brückenmodul.gh (11.6 KB)
Brückenmodul.3dm (72.2 KB)

Flatten the point input:

wow, you guys are amazing! Thanks!
i’m shure, i have other questions later

Hello everyone

I have another question. Based on your solution of the 3D axis, I was able to visualize the bridge cross-section using Loft (later it will also be Sweep). But now our bridge has an intersection at its end and must therefore diverge at the edges (see picture). The axis goes straight ahead, the edges should follow the yellow radii.

Unfortunately, the edges are only 2D. Because their height depends on the transverse slope of the cross-section.

So I need a function with which I can extrapolate the cross-section in 3D up to the edges in 2D.
Does anyone know advice and a solution here?
Brückenmodul.3dm (34.9 KB)
Brückenmodul.gh (8.8 KB)