fitcrv.rar (148.3 KB) The attachment test 3dm file has two curves,the right curve is the original curves, the left is the result curve of using fitcrv commnd or rhinofitcurve sdk function created.
The quick answer is to fit to a looser tolerance. 0.01 gives a very nice result.
If you want to investigate further, use the CurvatureGraph command and you will see an area of noise. In this location, there are points where the distance between them is very small. If you remove them, you can use a tighter tolerance. But for your application, a looser tolerance should be sufficient.
thanks very much