choosing from variety of curves

while modellung with curves when should i choose nurbs curve, bezuer curve, path.how do they differ…which is better than which in what cases?thank you

i rarely ever use curves, so if you get a reply by someone else who seem to know about it then go for whatever they say, but here is what i use curves for.

Nurbs Path:
Usually used when you want to parent something to it, and have it either follow that “path”, or if you want to extrude it along the path.
example would be:
Follow the Path: Tank - Car - Walk Cycle - Spaceship
Extrude along the Path: Snake, Tunnel, Tube, Bones, Tail

Bezier: stuff that has to be smooth; ropes, shoelaces, knots
Circle: Tank belts… all i can think off…

Nurbs curve/circle:
Basically the same as all other curves, but here, instead of drawing the curve in between each point (“vertex”), it draws it… well kinda like if it had a subsurface?
just add all the curves next to each other and you will see what i mean.

http://www.blender.org/manual/modeling/curves/introduction.html

Basically bezuer is used as a guide to form curved shapes like twisting pipe, or moldings. Nurbs is used to form curved surface like hull. Path is used in animation; an object move in a path.

I have a problem with Blender 2.74 Nurbs though. It is not working. I cant make a face with F key. Bugged?? Anyway here is good example of how Nurbs is used.

isnt that basically the same as normal modelling with subsurface? what is the difference?

Yes at the end we are dealing with mesh. But the surface must be described some how. This is where spine comes in. Until after the WW2, the description of The organic surface was done with wood strip called “spline”.

http://www.frets.com/FretsPages/Luthier/TipsTricks/DraftingWeights/DraftWeightViews/draftweight02.jpg

When you pin down given points, the spline bends in given way where bending load is evenly distributed; an ideal curvature. It describes the entire form. Nurbs is the mathematical solution to the wooden stick spline. It describes where you need to put the mesh.