Now that we've looked at components, there are a few different geometry types in Maya that we should consider. The components that we looked at previously were on a polygonal sphere. And there is a row of polygon objects. This is a polygon sphere, a polygon cube, and a polygon cylinder. So if I go into Component mode and choose a vertex on this polygon sphere, I can see that translating those points around gives me a one-to-one relationship on the surface. It's very literal about where I place that point, draws the edge directly to the next point. This is not the case with a nurb sphere. If I right click and choose Control vertex on the nurb sphere, that's the equivalent of the vertex on the polygon sphere, rough equivalent, and I go and select one of these CVs, as the Control Vertex is known, I get a much broader fall-off on the surface based on where that Control Vertex is positioned. And the same is true with this subdivision surface sphere. I'm going to right click, choose Vertex, and here I can see there's only four, I should say eight vertices drawn on the subdivision surface, four around the top, four around the bottom, and so this gives me a very, very broad or generalized control in this mode as I translate that point around. And the reasons for these different types, the way that they behave, if I take a look at the nurbs sphere and then I take a look at the nurbs cube and at the nurbs cylinder, these are actually all created from the same essential stuff, which is a four-sided patch, which has then been worked into different shapes. The cube is actually, when you go up the Create Nurbs Primitive Cube, you're not really creating a single object. You're creating a collection of objects because of this limitation of nurbs surfaces where they're each going to have four boundaries and then their points are moved around to create a non-planer shape. So this little plane that I have here, that's the real basic building block of a nurb surface. If I take a look at this cylinder, this is not a water-type object. Obviously it has a hole at the top and the bottom, but even the side is not sealed up. I'm going to select that nurbs cylinder sphere and then head over to the channel box, and I can see it has an input here called Make Nurb Cylinder 1. If I select that, Make Nurb Cylinder 1 item, I see I have an option for the radius, the start sweep, and the end sweep. So the end sweep angle right now is 360 degrees. If I hae that to 180 and enter, I can see something that is approaching a plane, and that's really what this nurb surface begins life as. It's then swept around in a circle to create that cylinder. And in fact the same is true with the nurb sphere. Let me create a new one up on my surfaces shelf and bring that guy over here and select the same End Sweep, and I'm going to use a little trick here where I highlight the name instead of the number and with that highlighted, head over to the model view or camera view, hold down my middle mouse button, and I get this little double-ended arrow, and now I'm going to left drag and right drag. That increases and decreases the value in that field. And here you can see I'm again, approaching something that's like a plane. In fact, if I take this nurb cylinder and set it back to have an end sweep of 360, let me go ahead and increase the number of spans on this, and then choose Control Vertex. We'll select this entire top row and scale that in, and do the same at the bottom. You can see this is what the nurb sphere's actually made from. And then I can go and bulge that center out a little bit and it's not perfect sphere, but that's exactly what that sphere there is made from. It's the same type of object. So the polygons are very literal; the nurbs have this very loose representation. Sub division surfaces are interesting because they allow you to get this very generalized feel, but you can also increase the detail level in an area, so with this one vertex selected, if I right click over the subdivision surface or sub D sphere, I can see that there's a Refine Selected option and by refining that I've added detail in this one little area. So now I get control at a greater level or a finer level, and I can do this again. Select one vertex, Refine Selected, and now I have really a high level of detail over just this one area.