Problems: Curvature Graphic on Surface using iso curve.

Replies to This Discussion

Permalink Reply by David Rutten on November 25, 2013 at 4:44am

I wonder if Rhino uses surface curvature measurements instead of isocurve curvature...

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David Rutten

david@mcneel.com

Permalink Reply by Gene Kao on November 25, 2013 at 11:32pm

Hi David, 

I have tried as many surface curvature method as I could, but none of them fit........

methods include:

Gaussian

Mean

Kappa

SurfaceCurvature in rhinoscriptsyntax 

Maximum principal curvature

Minimum principal curvature

by the way, look at this picture....  if I only use surface curvature the result doesn't seems right as well. Maybe I did some mistakes? thanks :)

Gene

import rhinoscriptsyntax as rs

import Rhino as rc

a = []

b = []

if ((u or v) is None):

    u = 0.5

    v = 0.5

c_u = Srf.IsoCurve(0,u)

c_v = Srf.IsoCurve(1,v)

if (Density span class="s4">2 or Density is None):

    Density = 2

if Scale is None:

    Scale = 6

ScaleFactor = -Scale

for i in range(0, Density+1):

    Normal_u = Srf.NormalAt(i/Density, u)

    

    su = Srf.CurvatureAt(i/Density, u)

    #s = Srf.CurvatureAt(0.5, 0.5)

    #print(s.Kappa(0.5))

    

    Normal_u_length = rs.VectorLength(c_u.CurvatureAt(i/Density))

    #Normal_u_length = Normal_u_length*rs.VectorLength(s.Direction(0))

    Normal_u_length = Normal_u_length * su.Kappa(0.5)

    

    Normal_u= Normal_u*Normal_u_length

    

    #print(type(Normal_u))

    Point_u = c_u.PointAt(i/Density)

    

    a.append(Point_u)

    b.append(Point_u + Normal_u*ScaleFactor)

    

for i in range(Density+1):

    Normal_v = Srf.NormalAt(v, i/Density)

    

    sv = Srf.CurvatureAt(v, i/Density)

    Normal_v_length = rs.VectorLength(c_v.CurvatureAt(i/Density))

    Normal_v_lengthTuple = rs.SurfaceCurvature(Srf, [v,i/Density])

    Normal_v_length = Normal_v_length * Normal_v_lengthTuple[7]

    Normal_v = Normal_v*Normal_v_length

    

    Point_v = c_v.PointAt((i)/Density)

    

    a.append(Point_v)

    b.append(Point_v + Normal_v*ScaleFactor)

mid = int(len(b)/2)

bu = b[:mid]

bv = b[mid:]