From the course: AutoCAD: Advanced 3D Modeling

Sculpt a NURBS surface using its CVs - AutoCAD Tutorial

From the course: AutoCAD: Advanced 3D Modeling

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Sculpt a NURBS surface using its CVs

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- [Instructor] Now let's turn our attention to modeling this battery compartment here, and with this design, my intention is to create something that looks kind of like a retro motorcycle tank, so this battery compartment is going to be bulged and curved. I'm going to isolate this layer. I'll type LAYISO, enter, and click on this, and press enter. Now at this point, we have a polyline path, and I'd like to turn this into a surface, so I'll go to the surface tab, use the planar tool, and use the object option, and click on this object, enter. Erase defining objects? No. So now we have a planar surface. Now I'd like to convert this into NURBS. NURBS is an acronym that stands for non-uniform rational basis spline. It's basically a kind of math that enables additional manipulation in different capacities to your surface. I'd like to convert this surface to NURBS. Erase defining object? Yes. So now I have a NURBS surface, and it looks exactly the same as the planar surface, however, as I said, there's more capacities now. To access those capacities, we can show the CVs. CV stands for control vertex. So I'm going to click on that, click on the NURBS surface, and press enter. Now we're seeing CVs as these little blue dots, so there's only two in each direction. That's really not enough to really effectively sculpt this surface. I'm going to rebuild this surface. I'll click rebuild, and then click on the NURBS surface, and we can change the number of control vertices in each direction. You see, the NURBS surface is defined by its own internal coordinate system that runs in the u and v directions, so I'm going to change the number here to four and four. I'll just say okay and leave all the other things at their default values. So now we have four CVs in each direction. This gives us additional editing power. Now I'd like to change the shape of this surface by moving the CVs. To select CVs, you hold down the control key and click on them, and then they turn red. So I'm going to keep holding down the control key, and click on these four central CVs, and then I'm going to move them up in the blue direction, and as I do that, you can start to appreciate the kind of magic of NURBS math. This allows me to deform this surface by altering the shape of this lattice. So I just move them up and now we have a bulge in that surface. We can leave it just like that, or we could refine it even further either by moving these CVs, or adding additional CVs, and so on. I think I might want to just do a little bit more manipulation here. I'm going to control + click. Actually, I'm going to press escape a couple of times to deselect, and then I'll control + click on these two CVs right here, and then I'll move them up a little more so we have the bulge being this nice arc all the way across. In the next video, I'll show you how we can mirror this and then join the two NURBS surfaces together to finalize the design of the battery compartment.

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