From the course: 3ds Max 2021 Essential Training

Correcting a seam with Non-Uniform Scale offset - 3ds Max Tutorial

From the course: 3ds Max 2021 Essential Training

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Correcting a seam with Non-Uniform Scale offset

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- In the last movie, we use transform constraints to shape the sub objects of this seat cushion and create a depression between the cushion and the base. We just pushed these vertices here inward along their local normals. That unfortunately introduced some error at the seam, where the two halves of the symmetrical model are joined. So let's investigate. I'll select that object, go to the Modify panel, go to the symmetry modifier, and we'll show end result enabled, we can see the effect of disabling weld seam, turn off weld seam and get in close on the seam. And we can see that we've got some problems there. And if we turn show end result off, we can see the original mesh or the control cage. And that might even be an easier way to visualize these problems. So with weld seam on, then that gap is closed automatically if those two vertices are within this threshold, as we reduce that threshold, fewer vertices are merged or welded. And with a threshold of zero, it's the same as having weld seam disabled. Alright, I'll set that back to 0.3 centimeters or so, go down to the level of the editable poly, the base object in the modifier stack. And we want to correct the issues at the seam at this open border. To make it easier to see, let's hide everything else, right click in the view, and choose isolate selection getting close in the top viewport. And we can see some problem there, where the points on the model are not all at the same x position. We want to move all those vertices to an x position of zero. But unfortunately, there's actually no way to do that using the move tool. We can't just select a bunch of vertices and tell them to all go to an x position of zero. But there is a workaround for that, and that's to use scaling, and to scale to a value of zero. Let's select the sub objects at the seam. That's a border. If we tumble around with Alt and middle mouse, we've got an open border, which is a series of connected edges, in which there's only one polygon per edge. Let's go into border sub object mode, and click on the Open border. That was easy. Now we want to scale, and we want to scale non uniformly. And we want to scale relative to the world grid. We have the world grid already, because we're in view coordinate system, that's our reference. If we grab the Scale tool, and we just scaled in world x, we would actually pretty much get where we want it to be. We can see that we've flattened that shape out here. There's a more precise way to do that. I'll undo that. And instead use non uniform scaling, in offset mode. We've got the scale elective. The default mode is select and uniform scale, click and hold that button and you get a flyout. The second button, the one in the middle is select and non uniform scale. Choose that. And now we can easily scale selections of sub objects, we just can't scale them in an absolute value. In non uniform scale mode, we have separate access to the X, y and z scale values. However, we don't see them in our transform type in here, it's all grayed out. This is so called absolute mode, there's a little button over here tells us we're currently in absolute mode. We need to be in an offset mode in order to scale non uniformly at the sub object level. Click that button and it switches over to offset mode, button turns blue and now it looks like a circle with two arrows one facing to the right and when facing downward. And our X, Y and Z axes are no longer grayed out, we can just set the X value to zero. And now we know for certain that we've scaled all of those selected edges, or that border to an X value of zero, using the world as our coordinate system, because we're in view reference coordinate system. All right, very good. I'll switch back over to absolute mode, and switch back over to select and uniform scale. Exit out of border sub object mode. Go back up to the symmetry, in real close there, maybe turn off the Scale tool, just go back to the Select Object tool. And even if we turn weld seam off, we don't see much of a change. There was a little bit of a shading issue there. And it's simply because these are two separate shells. When weld seam is on it becomes one shell. Go back up to the open sub div and we can see that we've got a perfectly clean model that's how to correct issues at the border of a symmetrical model using non uniform scaling and offset mode.

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