CGAL 5.3  3D Spherical Geometry Kernel

Operations  
SphericalKernel::Line_3  operator() (const SphericalKernel::Line_arc_3 &s) 
Constructs the line containing the segment.  
SphericalKernel::Line_3  operator() (const SphericalKernel::Polynomials_for_lines_3 &p) 
Constructs a line from an equation.  