The Surface from Curve Network command is used to form a mitten volume and Ellipsoid is used for the thumb volume. Both surfaces are trimmed back so that the Surface Blend command has room to do its work.
- [Instructor] In this next video, we'll keep our hands warm by modeling some 3D mittens. We'll build the larger part first using the Surface from Curve Network and then blend it to the smaller thumb part. First, let's highlight the difference between a blend and a fillet. A fillet, on the right, usually has a fixed, or constant, radius. This is a lower-degree surface, and generally looks more mechanical. You can fillet two surfaces whether they touch or not, although most people will join them first.
Secondly, a blend, shown on the left, is a higher-degree surface and lets the radius vary as needed to generate a continuous and essentially a smooth single surface. This is the best way to connect organic geometry. Now, you cannot blend if the two surfaces touch, so you do need to trim both back. We'll cover that coming up. Let's zoom out and start some drawing. Going to work down here on the on the construction plane. I'm going to first start with an ellipse for the form on the bottom end of the mitten.
We'll select the ellipse, but I want to go over here and make a few changes. First of all, we're going to select deformable. That will make it a degree 3 automatically and avoid any pinching points. Secondly, I'm going to make some changes to the point count here. I'm going to make eight points. Now, let's start this from the center, which will be at the origin. We're going to come out a little bit of a ways here. I'm going to gold down Shift and then we go the opposite way, which is the shorter direction. I'm going to keep this relatively flat.
So we go ahead and select it, hit F10, turn on the control points. And you can see, it looks a bit different than the normal ellipse. Also, none of these will cause any pinching. So this is the beauty of a deformable, or degree 3, curve. I'm going to make this a little bit more square, so I'm going to do a nice little trick here by picking these four semi-corner points, and then scaling them outwards. So we'll give over the the Scale 3D. I'm going to pick the origin at the origin right here, 0.00.
And then the reference point doesn't really matter. We can just click somewhere randomly. The pull point is going outwards and getting those guys away from the center. So you can see I made that a little bit more squarish. It looks kind of like a rounded rectangle. Let's turn the control points off with F11, and I'm going to zoom around here and switch over to the Front viewport. We're going to draw the side profile. We'll do this with a Control Point Curve here on the main toolbar.
You can also start in one viewport and finish in another. So in Perspective, I'm going to make sure that I snap to the inner section there. If it's not set for you, just come down to the Osnap area and click on Intersection. So back to the Front viewport. We're just going to come up slightly, make one or two steps, and then I want to hit that axis with perpendicular snaps, so that's also on for me. Now back in Perspective, I want to zoom out a bit here, so we can see what we just drew.
Looks like a fairly simple curve. The one thing you might not have noticed is I made sure the last two point hit perpendicular to this axis line we're about to mirror. Now that's actually really important, because if they're not in alignment, we could have an opening or a little pinch or a little pucker, so let's keep those in perfect alignment. So we can actually move them around. I'm going to go this by going to the Front viewport, and just dragging them up a bit. But just make sure you get both of them together. I'll turn the control points off with F11, and also the Front viewport, let's go ahead and mirror that.
That's under Transform, Mirror, and I can pick any two points that are in alignment, maybe from the endpoint there at the top of this red axis line. So in Perspective, you can see that they look really clean and nice. Now let's get the profiles going in the other direction, which is the more narrow side. We do the same exact Control Point Curve. We use this Perspective viewport to make sure we snap there. I'm going to come over here to the Right viewport to keep drawing it. Now this gets a little bit tricky.
I want to make sure that the last two points hit this exact spot. I'm not kind of just wingin' it like I was in the first curves. So it can help us guide it in with the SmartTrack. So I want to have the second-to-last point right around here but I want to look at that very last point. So now I can click there and finally at the end. It's a little bit difficult to see sometimes, so it takes a little bit of practice, but that SmartTrack, that's probably its best use right there is to line it up with stuff without having to come back and fix it.
If it looks a little bit deformed, we can just turn the control points on, and with F10, and make those any shape we want. Okay, I'm going to turn them back off, F11, and we'll try a mirror here in the Perspective viewport, that might be kind of fun. So we've got that short profile selected. Go to Transform, Mirror. Now I'll use some of the axis lines to snap, so I want to start with the origin there, and maybe click on the endpoint far away. It looks like it worked pretty good.
I did notice the SmartTrack keeps lighting up, so after I use it, I typically will turn that off. So we've got a series of very simple and clean curves here. It looks like we can go ahead and just now use the Surface from Curve Network, so I'll just select all four of these with a crossing window and then the bottom ellipse. So I got 'em all selected, the command is under Surface menu, Curve Network. I'm going to go ahead and accept all of these defaults.
Hit OK, and then we have a nice, clean, organic mitten body section. I'm going to go ahead and maybe click on the Front viewport. I'm going to grab this ellipsoid shape already made. We'll just kind of drag it over there. I do notice it kind of of a big thumb. Let's go ahead and scale it down quickly and easily here. We'll use the 3D Scale, so we get no deformation. I'm going to snap on this endpoint, and then just kind of eyeball the change in size here.
Looks good enough for now. Okay, one of the keys for blending is we got to make sure the surfaces both overlap and are trimmed back. That's usually the way to go. So I'm going to drag this guy over to there. Now I'll make some cutting curves. Zoom in just a little bit. We'll stick with the Control Point Curves here. It's always helpful to visualize how this blend will happen in multiple occasions. So it's going to be a nice little blend up here, and then probably a larger arc or radius down below.
Another trick to do is make sure you kind of cut across at roughly 90 degrees. It's not critical, but it keeps things a little bit cleaner. So that line is almost straight, but that tells us that it'll be trimmed from here and we can wrap it right up. Next one will be definitely more curvy, so I do another Control Point Curve. However, we might want to just go ahead and switch to Wireframe if it's getting a little bit busy here. That may help some people zoom in here, so I'm going to cut across again and try to hit it roughly at a perpendicular angle, and looping around, fairly simple and cleanly.
And exiting here, also trying to pay attention to distance that we're going to go across here. It should be relatively equal, or something you feel comfortable with. Okay, so we got those two shapes drawn. It looks like it should be a nice little blend and go ahead and make minor adjustments. Move them around, you can also turn on the control points and modify those a bit. So I'm noticing the distance here looks like it should maintain that curvature just fine, so I'm going to go ahead and turn the control points off with F11, and we'll switch it back to Shaded view.
So we can also trim these both at the same time, which is kind of cool. I'm going to go over to the Trim Commander in the Main menu. The cutting objects, I'm going to select the two curves, even though we can't see all of them. Right-click to accept. And then the objects to trim, we'll just pick these pieces we don't want from both parts and then right-click to finish. So now we can kind of see what's happening, where the blend will occur across there. It's going to be much wider over this section, and then have a second dimension from this part.
Okay, I'm going to go back to the Perspective viewport by double-clicking on a few viewports here. And the final command we'll do is Surface Blend. Here is is, kind of down towards the bottom. We're going to select the opposite edges that we've trimmed back, so look at the command line if you're not sure. So I'm going to select this edge. If it lights up all the way around, that's a really good sign. It's not too complicated. So I'm going to right-click to let it know I'm done. I'm going to select the opposite side, and it goes ahead here and you notice Rhino tries to guess opposite seamed points.
I'm going to actually try to line those up. I typically move those to either the nearest or farthest point, so it seems a little better result when you do that. So I'm just putting those both, notice how I snapped the intersection of the surface and curve, and those little red arrow seam lines are pointing in the right direction. So when that looks okay, you can just right-click to accept. We get the pop-up here. This is typically a little severe, so you can dial these back here a bit.
Also, if that little curve isn't enough information, we can hit Preview and it'll generate the entire surface, so you can do a little more manipulations there. So watch out for doing too much the other way. Things can definitely go crazy and turn inside-out. So I'm typically pulling those back to have less of a blend. Go ahead and hit OK. So there we have a really clean transition. It does, however, look a little bit busy, so what I recommend is maybe joining these all together, selecting them with a Shift, and the Control + J to join, and finally, this is more of just a visual preference for me, but I like to turn the isocurves off at certain points, just to kind of enjoy how smooth the result is.
So the blend is a beautiful way to create amazing organic surfaces, but it needs to be done correctly. The trick is to visualize the flow of the new blend surface and then trim back the other two surfaces at just the right amount. However, don't hold back. Most people will not trim enough, and end up with what looks like a filet because they're way too close together.
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