@pcrespo By the way. Converting to Solid (using either method) only works well when a) the mesh resolution is not too high (else it will take forever and use huge amounts of memory) b) the surface mesh is manifold and has no self-intersections. these defects can be identified and often fixed using the Mesh Doctor ("Automatically Fix"). [image: 1525763911163-d38bb2c1-efd5-4038-b84a-605be284dda1-image.png] [image: 1525763920888-3d828313-84bb-4410-9be9-d584b6318823-image-resized.png]

got it: wire = GetWires(spline)[0] curve = wire.GetGeometry(transform_to_model_space=True) law = curve.GetLaw() t0 = curve.MinDistParameter(point_start)