Join Veejay Gahir for an in-depth discussion in this video Rebuilding surfaces, part of Alias Essential Training.
- Let's continue on with rebuilding surfaces. Let's click on the surface layer. I'm gonna rotate and zoom into this entity here. Let's select this entity. This is a router. We can tell just by looking at this surface that the profile that was used during this route was probably quite a heavy curve, so the resultant surface is quite undesirable. We're gonna try to reduce that complexity. I've just put a little not here telling me that it's a degree 3X1, 8X27 span surface.
Let's go into Surface Edit, Rebuild Surface. Let's do a reset. These are very similar options that we've used during the curve rebuild. Let's start off with Reduce spans. I'm gonna pick the surface, space bar to accept. Before I do that let's click on all these options here. Now with Reduce spans, again as with curves, Alias tries to reduce the number of spans within this particular tolerance. Right now we have an 8X25 span so we haven't done that great.
But if we do increase or loosen up the tolerances here let's see what that does. We've jumped down to 8X9 spans. That's quite a big change, and the deviation that we're looking at here is ... Let's just look at this. It's three millimeters. That's not too bad. If I go ahead and just move this data, move it down. And let's just press L. We can see that that is, sure enough, quite a lighter surface compared to the original.
Let's delete that. Let's go back to Rebuild surface. We'll do a reset and we can go to the next option which is Delete multi-knots. Again, in this case, here we don't have multi-knots in this particular surface. But if we did, very simply we would just pick the surface, press space bar, and it would delete those multi-knots. Let's undo all. Let's go down to the next option which is Uniform rebuild. With Uniform rebuild see that we have the options to change the number of CVs and change the degrees which is what I really like to do, I like to have control over the rebuild just like we did with the curves.
I'm going to go ahead and select this surface with those options deselected, press space bar. And let's just simply move this down and press L. It hasn't really done a lot as far as reducing the actual numbers of spans here. But what you can see here is that the distribution of those spans are very uniform. In this example here you can see that we have two spans where my cursor is, quite close. Then we have a big expanse of no spans and then we start going into more spans. This one has distributed them quite uniformly.
Let's delete that. Let's go back to that option and this time we're going to switch on CVs and degree. It defaults at 3X3, 3X3. With a surface this complex there's no point going down to one so let's see what we have with this. We'll press go to that. You see the deviation here. We have deviation of approximately 18 millimeters. That's quite high so we can start increasing the number of spans. I'm gonna leave the degrees at 3X3 and let's go to 6X6, and that's a lot better result.
We're at 1.6 millimeters and we're at 6X6 spans. Again we've done a pretty good job on reducing the complexity. I've moved that down. Select nothing, press L to delete those locators. This is what we have. Let's delete that. Let's go back to rebuilding and we're gonna do a reset. The next option is Match knots. Again, I always like to have these checked on. And again, very similar with curve. We select the surface, space bar.
Alias is telling us to select an object on which to get the U-knot parameterization for rebuild. This is the surface we're going to use as our reference. Which is the U and V direction? We can do that check very quickly by simply selecting that surface and switching off the Us. The U's are the radial and the V's are the ones that go from top to bottom. Let's go back to this. Select the surface, space bar to accept. Now we have to select the U, which is this one. Now Alias is telling us select the V parameterization which is this one here.
Let's check the deviation. Minimum 0.4, maximum 6 millimeters. I'm going to say Move and move it down like that. Let's press L. You'll notice it hasn't give us a great result and also you might be expecting to see this parameter at the top like we have in this example here. That's not the case. It's actually just tried to mimic the number of spans. That's an 8X2, and this one here's an 8X2. It tries to redistribute those the best it can to give us the best result. It won't necessarily mimic it exactly, position-wise.
Let's delete this. Let's go back to here. Let's open this back up. The next option here is to go simply to Rebuild. You'll notice that the options for Rebuild and the options for Uniform rebuild are virtually the same. It's just that with Rebuild we don't have a uniform distribution of the parameters. Again we can go with this option. Spacebar, and we can move down. Then press L. We see it's given us pretty much the same result.
But I do have the option to override that with my own number of CVs and Spans. We knew that 6X6 gave us a pretty good result. Let's go ahead and pick that, space bar. And we're gonna move this down. And that's the result it gets. In this case here, those two options for rebuilding are probably the best ones to use. And those would be Rebuild or Uniform rebuild.
- Manipulating views and entities
- Working with layers
- Creating curves
- Sweeping, extruding, revolving, offsetting, and blending surfaces
- Modifying geometry
- Moving, scaling, flipping, and rotating objects
- Trimming curves and surfaces
- Creating copies of objects
- Aligning, combining, and splitting objects
- Analyzing geometry
- Shading models