Is there a command to find the ‘average’ or ‘middle’ curve between two curves…? I want to find the centre line between these two curves - the north and south extents of the Thames [image] TIA

TweenCurves | Rhino 3-D modeling The TweenCurves command creates curves between two open or closed input curves.

thanks @DanielPiker . Unfortunately the black line is the best I can achieve with the Tweencurves command - using MatchMethod=SamplePoints; SampleNumber=10000 [image]

The most accurate way to create an average curve between two input curves is to use Loft and extract the middle isocurve of the resulting lofted surface. Both of your curves pictured above appear as if they include multiple self-intersections, so this may be a challenge.

[image] Bobi: The most accurate way to create an average curve between two input curves is to use Loft and extract the middle isocurve of the resulting lofted surface. Well, not really. it might only work OK, if both curves has exactly the same number of control points so that Loft could mat…

I would take one of the curves, and then sample it with points, then find the closest point to the other curve, and take the average: [image]

I wrote “The most accurate way”, because it’s exactly that. :slight_smile: Loft works perfectly fine with curves consisting different amount of control points. The main problem in the two curves of the author is that they are overly-complex, so it’s nearly impossible to get a nice looking intermedia…

[image] Bobi: The most accurate way to create an average curve between two input curves is to use Loft and extract the middle isocurve of the resulting lofted surface. I disagree. Loft creates isocurves between points at equal fractions of the parameter range of each curve, which are not nece…

“Loft” is the tool that creates the exact average between two curves/surface edges. Just because the outcome is not looking good does not mean it’s not average. On contrary, the “Add slash” option of “Sweep 2 rails” may result into achieving a controlled, slightly more “likeable” output surface, tho…

One way to look at this is as trying to find a new curve for which all points have their closest point on the 2 input curves an equal distance away. Here’s a way using Grasshopper to do a simple sample and sort to find this [image] avgcrv.gh (12.5 KB)

Note that this approach still needs a very rough approximation of the curves to get the lines to search along. Using simple straight lines above and below will work to get rid of the inlets, but will mess up in regions where the whole river doubles back on itself. [image] Whereas drawing a guide…

Finding the average curve between two curves

Rhino Rhino for Windows

Gijs (Gijs de Zwart) October 25, 2022, 8:47pm 13

I was also thinking about fitting in some circles and running a line through their centers:

avg_circles.gh (9.9 KB)

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Finding the average curve between two curves

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