def b_spline_centerline(x_centerline,y_centerline,z_centerline):
print '\nFitting centerline using B-spline approximation...'
points = [[x_centerline[n],y_centerline[n],z_centerline[n]] for n in range(len(x_centerline))]
nurbs = NURBS(3,3000,points) # BE very careful with the spline order that you choose : if order is too high ( > 4 or 5) you need to set a higher number of Control Points (cf sct_nurbs ). For the third argument (number of points), give at least len(z_centerline)+500 or higher
P = nurbs.getCourbe3D()
x_centerline_fit=P[0]
y_centerline_fit=P[1]
Q = nurbs.getCourbe3D_deriv()
x_centerline_deriv=Q[0]
y_centerline_deriv=Q[1]
z_centerline_deriv=Q[2]
return x_centerline_fit, y_centerline_fit,x_centerline_deriv,y_centerline_deriv,z_centerline_deriv
def b_spline_nurbs(x,y,z,degree = 3,point_number = 3000):
from sct_nurbs import NURBS
print '\nFitting centerline using B-spline approximation...'
data = [[x[n],y[n],z[n]] for n in range(len(x))]
nurbs = NURBS(degree,point_number,data) # BE very careful with the spline order that you choose : if order is too high ( > 4 or 5) you need to set a higher number of Control Points (cf sct_nurbs ). For the third argument (number of points), give at least len(z_centerline)+500 or higher
P = nurbs.getCourbe3D()
x_fit=P[0]
y_fit=P[1]
Q = nurbs.getCourbe3D_deriv()
x_deriv=Q[0]
y_deriv=Q[1]
z_deriv=Q[2]
return x_fit, y_fit,x_deriv,y_deriv,z_deriv