Trim and untrim limit surfaces

00:04

Adding cutout details or holes using only the control cage

00:09

means that you've got to add a lot of geometry

00:12

which adds complexity to the subdivision.

00:16

The alternative is to keep the control

00:19

cage simple

00:20

and then create the detail on the limit surfaces using the NURBS trimming tools.

00:26

So I'll go back to my untrimmed subdivision

00:29

and I've created some curves here in this view.

00:33

And I'll start by using the Project tool to create some curves-on-surface.

00:38

And this defaults to the view direction which

00:40

would work as I am in this orthographic view

00:43

or if you prefer to work in perspective, then you can choose the axis.

00:48

So in this case, I'll project along the X direction.

00:52

But the most important option is this Subdiv Select

00:56

because when it's asking me to select the NURBS surfaces,

00:60

I can just click once on the subdivision

01:02

and all the limit surfaces get selected.

01:05

So I'll say Go

01:07

and then it says "Select the curves" and I've got three here.

01:10

So I can box select those and say Project

01:14

and that creates a curve-on-surface which is drawn on to the limit surfaces.

01:21

But also the projection has gone all the way through.

01:23

And I've got one here at the front

01:25

and a bit here too.

01:27

So I can use this Limit Projection option here to reduce that.

01:31

And I don't need to be too accurate. Just make sure that it only covers the area I need.

01:37

So these five limit surfaces have curves-on-surface

01:41

and so the boundaries are shown dotted for these.

01:45

But I've also got these two spare ones,

01:47

which is why the Trim tool also has this Subdiv Select option.

01:52

So again, I can click on the subdivision to activate all the surfaces

01:56

and then select here.

01:58

And I don't want to keep that I'll do a Discard instead

02:02

and that then hides those two spare surfaces and trims these five

02:07

and changes the outline color to yellow.

02:11

And it's got construction history, so if I change the filet radius, for example,

02:16

the trimmed region will update

02:19

and I'll get a more controllable and precise cutout

02:21

shape than I could with just the subdivision vertices,

02:25

and any changes that I make will always update the trim.

02:30

Now with this circle for the badge area, I'm not gonna want to project that in X or Z.

02:37

So in project I can choose the Normal vector option.

02:40

So if I pick the subdiv it's gonna go 90 degrees to the surface. So I'll do a Go

02:47

and pick the curve and do a Project.

02:50

So I'll just hide the curve layer. So you can see the curve-on-surface here.

02:55

And then I can just do the trim,

02:57

pick the subdiv and Discard.

03:02

So I've added detail without adding complexity to the subdivision cage.

03:09

You can also Intersect to create curves-on-surface.

03:13

So let's say I've done a quick exploration of this roof wing

03:17

and I've kept the face layout simple and I haven't yet

03:19

worked out how to combine the two subdivisions along this join.

03:23

So I can intersect the limit surfaces instead.

03:27

And again, it's got the Subdivision Select options.

03:29

So I can just pick one whole subdiv

03:32

and then Go

03:33

and then the other.

03:35

And if I take the shading off, you can see that the curve-on-surface has been created.

03:40

Now for trimming the curve-on-surface has got to go all

03:43

the way to the end and here this one's a bit short,

03:47

but there's an option on Trim called Extend

03:50

and I'll use Selected which displays an arrow here where there's an issue.

03:54

So if I click on that,

03:56

it will delete the construction history, but that's OK.

03:59

So I'm just going to select here and say Keep

04:03

and it will be the same for this one.

04:05

This end is OK.

04:07

But I can see an arrow here as it's a bit short. So I can click on that to extend

04:12

and then pick this region and Keep.

04:17

So that's done a quick tidy up which might be

04:19

useful for a design review or a screen grab.

04:23

Now there isn't an undo with trimming, but we have Untrim instead

04:28

and this Last option will undo step by step.

04:32

So if I click here, it does

04:33

that trim from the intersection

04:35

but not these ones.

04:37

And then if I click again, it'll untrim in sequence.

04:42

Or if I do an Untrim All, then everything is untrimmed here

04:46

and here.

04:48

And it's good practice to delete any curves-on-surface you don't need for trimming.

04:53

And there's a specific Pick tool here

04:56

and I use that a lot, so I've added it to my marking menu as well.

04:59

So I can just box select and delete the curves-on-surface.

05:04

And finally, if you use these tools a lot, it can be useful to add them to your shelf,

05:10

particularly the Project tools in the different directions

05:13

and the Trim and Untrim.

Video transcript

00:04

Adding cutout details or holes using only the control cage

00:09

means that you've got to add a lot of geometry

00:12

which adds complexity to the subdivision.

00:16

The alternative is to keep the control

00:19

cage simple

00:20

and then create the detail on the limit surfaces using the NURBS trimming tools.

00:26

So I'll go back to my untrimmed subdivision

00:29

and I've created some curves here in this view.

00:33

And I'll start by using the Project tool to create some curves-on-surface.

00:38

And this defaults to the view direction which

00:40

would work as I am in this orthographic view

00:43

or if you prefer to work in perspective, then you can choose the axis.

00:48

So in this case, I'll project along the X direction.

00:52

But the most important option is this Subdiv Select

00:56

because when it's asking me to select the NURBS surfaces,

00:60

I can just click once on the subdivision

01:02

and all the limit surfaces get selected.

01:05

So I'll say Go

01:07

and then it says "Select the curves" and I've got three here.

01:10

So I can box select those and say Project

01:14

and that creates a curve-on-surface which is drawn on to the limit surfaces.

01:21

But also the projection has gone all the way through.

01:23

And I've got one here at the front

01:25

and a bit here too.

01:27

So I can use this Limit Projection option here to reduce that.

01:31

And I don't need to be too accurate. Just make sure that it only covers the area I need.

01:37

So these five limit surfaces have curves-on-surface

01:41

and so the boundaries are shown dotted for these.

01:45

But I've also got these two spare ones,

01:47

which is why the Trim tool also has this Subdiv Select option.

01:52

So again, I can click on the subdivision to activate all the surfaces

01:56

and then select here.

01:58

And I don't want to keep that I'll do a Discard instead

02:02

and that then hides those two spare surfaces and trims these five

02:07

and changes the outline color to yellow.

02:11

And it's got construction history, so if I change the filet radius, for example,

02:16

the trimmed region will update

02:19

and I'll get a more controllable and precise cutout

02:21

shape than I could with just the subdivision vertices,

02:25

and any changes that I make will always update the trim.

02:30

Now with this circle for the badge area, I'm not gonna want to project that in X or Z.

02:37

So in project I can choose the Normal vector option.

02:40

So if I pick the subdiv it's gonna go 90 degrees to the surface. So I'll do a Go

02:47

and pick the curve and do a Project.

02:50

So I'll just hide the curve layer. So you can see the curve-on-surface here.

02:55

And then I can just do the trim,

02:57

pick the subdiv and Discard.

03:02

So I've added detail without adding complexity to the subdivision cage.

03:09

You can also Intersect to create curves-on-surface.

03:13

So let's say I've done a quick exploration of this roof wing

03:17

and I've kept the face layout simple and I haven't yet

03:19

worked out how to combine the two subdivisions along this join.

03:23

So I can intersect the limit surfaces instead.

03:27

And again, it's got the Subdivision Select options.

03:29

So I can just pick one whole subdiv

03:32

and then Go

03:33

and then the other.

03:35

And if I take the shading off, you can see that the curve-on-surface has been created.

03:40

Now for trimming the curve-on-surface has got to go all

03:43

the way to the end and here this one's a bit short,

03:47

but there's an option on Trim called Extend

03:50

and I'll use Selected which displays an arrow here where there's an issue.

03:54

So if I click on that,

03:56

it will delete the construction history, but that's OK.

03:59

So I'm just going to select here and say Keep

04:03

and it will be the same for this one.

04:05

This end is OK.

04:07

But I can see an arrow here as it's a bit short. So I can click on that to extend

04:12

and then pick this region and Keep.

04:17

So that's done a quick tidy up which might be

04:19

useful for a design review or a screen grab.

04:23

Now there isn't an undo with trimming, but we have Untrim instead

04:28

and this Last option will undo step by step.

04:32

So if I click here, it does

04:33

that trim from the intersection

04:35

but not these ones.

04:37

And then if I click again, it'll untrim in sequence.

04:42

Or if I do an Untrim All, then everything is untrimmed here

04:46

and here.

04:48

And it's good practice to delete any curves-on-surface you don't need for trimming.

04:53

And there's a specific Pick tool here

04:56

and I use that a lot, so I've added it to my marking menu as well.

04:59

So I can just box select and delete the curves-on-surface.

05:04

And finally, if you use these tools a lot, it can be useful to add them to your shelf,

05:10

particularly the Project tools in the different directions

05:13

and the Trim and Untrim.

Video quiz

Required for course completion

When using the Project Surface Edit tool, after the curve is created and is being projected onto the surface, how do you prevent the projection from going all the way through the model?

(Select one)
Select an answer

1/1 questions left unanswered

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