From the course: AutoCAD: 3D Architectural Modeling

Shape a courtyard as a NURBS surface - AutoCAD Tutorial

From the course: AutoCAD: 3D Architectural Modeling

Start my 1-month free trial

Shape a courtyard as a NURBS surface

“

- [Instructor] Now, we're going to build a courtyard. This courtyard is actually filled with earth. We need to represent it's surface. On the top of this red wall, it goes around. So, let's begin by creating a new layer. Call it dash terrain. Set it current, and give it a dark green color. And then, let's trace the perimeter of the courtyard with a poly line object. Type pl for poly line, enter. Turn on object snap, if it's not already on. Turn off dynamic UCS if that's on. Start tracing the courtyard by clicking this end point on the inside of the red wall there. And then, work your way around, snapping to points as you go. Around the top of this perimeter. And then, type c for close, enter. So now we have a poly line object. Let's convert this into a surface. You can do so over here on the create rollout here, where we have this expansion of additional tools. What we need to do is use this tool right here, which is called plane surf. I'll click on that. Normally, you would click the same points that we did before. Fortunately, there's an object option here. So, we can use that. We can just click on the poly line. It will input all of it's vertices as inputs. And then, press enter. That generates a planar surface object. But, as it stands, this surface is completely flat. What I'd like to do is represent this terrain with a slight bulge in the middle, so that we can have drainage around the perimeter of the courtyard. We'll have a little bit of a rise in the middle. To do so, we need to change the workspace to access some more advanced modeling tools. Let's open the workspace switcher down here, and go to the 3D modeling workspace. This will open up additional modeling tools. We are interested in surfaces right now. So, go to the surface tab. What we need to do is convert this surface to NURBS. NURBS stands for Non Uniform Rational Basis Plane. Essentially, it's just a different kind of mathematical representation for this object. I'll select the planar surface and press enter. It actually converted this mathematically to a different representation. Now it's considered a NURBS surface, but it looks exactly the same. The NURBS surface gives us additional functionality. To access that, we need to show the surface's CVs. CV stands for Control Vertex. I'll click on, Show CV. And then, click on the NURBS surface and press enter. If you're especially observant, you may have noticed that there are little blue grips now, that appear on the edges of this surface. Those are the CVs. But, there's only one on each corner. That's not really going to give us enough editing power. So, we're going to re build this surface. Let's use this tool, and then select the NURBS surface. You get this dialogue box, where we can change the number of Control Vertices, or CVs, in the U and V directions. You see, every NURBS surface has these iso parameter lines that run in two directions. The U and V directions. I'm going to change the number of here to five and five. I'm using an odd number in each direction, because I want to have a row of CVs down the middle. I'll say okay. Now, we have a grid of five by five CVs running in each direction. To access these CVS, you hold down the control key, and click on each individual CV that you want to activate. That makes them hot, and turns them red. Now that I've selected just these three CVs running down the middle, I'll click on the blue arrow and move them up somewhat. You can see that that is deforming the surface. We don't want to go too far and make a giant mound, but we just want to lift it up a little bit, to suggest that this courtyard isn't entirely flat. Then, I'll press escape to de select. Finally, I'll hide the CVs globally, so we don't see those anymore. But we're left with a surface that has some subtle curvature to it, that will represent that courtyard in a more realistic way.

Contents