SUrface function

[navneet.kaurR777H]

Is there a way by which we can extract the function of a surface? I mean the surface function. Something like 

x^2 + y^2 + z^2 -1 = 0

[BrianEkins]

For analytical surfaces like planes, cylinders, spheres, etc. you can get the defining information, not in an equation form, but all of the information needed. Spline surfaces are similar in that you can get the underlying NURBS definition but not an equation that will define the shape.