& Construction
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Integrated BIM tools, including Revit, AutoCAD, and Civil 3D
& Manufacturing
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Professional CAD/CAM tools built on Inventor and AutoCAD
Integrated BIM tools, including Revit, AutoCAD, and Civil 3D
Professional CAD/CAM tools built on Inventor and AutoCAD
Transcript
00:02
For a symmetrical design,
00:04
we can either build one subdivision across the centerline like this roof
00:09
or build one half and then use layer symmetry either up
00:12
here in the layer bar or here in the Object Lister.
00:17
Building the whole shape will generally give us a smoother limit surface across the center.
00:23
Building one half is generally more efficient,
00:26
but we have to work harder to get a good result on this centerline join.
00:31
There are tools that can help us with both methods,
00:34
but they all rely on the symmetry direction set in each layer.
00:38
And this yellow plane defaults to a centerline along
00:41
the X direction which works for this car,
00:44
but that can be changed, so you need to be aware of the direction
00:48
as it's this layer symmetry, which is key to using the symmetry tools.
00:54
So I'm going to start with this roof that we've built as one half.
00:58
And if we wanted now to make that the whole roof,
01:01
then I've got two ways to get the other half.
01:04
I can use Edit > Duplicate > Mirror.
01:07
And the default setting of XZ gives us
01:09
the same result as the default layer direction.
01:12
And so I get the mirrored side.
01:14
Or if I delete that
01:16
alternatively, I can turn on the layer symmetry
01:19
and then say Create Symmetric Geometry.
01:22
And the end result is exactly the same.
01:25
And I've still got two separate subdivisions
01:28
so I can join them into one using the Weld tool.
01:32
And I'm gonna use the To Tolerance setting
01:35
and just drag over these coincident center CVs to merge them.
01:40
So you can see that that's been welded into a single subdivision.
01:44
But over here, the CVs weren't snapped accurately to the center.
01:48
So I can use Weld again with two midpoints
01:51
to join those together on the centerline.
01:55
And that then gives me a reasonable smoothness across the middle.
02:01
But of course,
02:02
the difficulty is that it's very easy to make a change and lose the symmetry.
02:08
So we have a tool up here on the subdiv shelf
02:11
or here on the palette in the Object Edit tab
02:14
called Symmetric Modeling.
02:16
And if I pick the subdiv,
02:18
it reads the symmetry direction from the layer.
02:21
And when I apply it,
02:22
it forces the geometry to be symmetrical in that layer direction.
02:27
And then down here, I can choose which side to use as the master.
02:31
And you notice that the subdiv is now green, which means construction history.
02:36
So if I pick and move CVs on one side,
02:39
then the same actions are applied to the other side.
02:44
But also the subdivision tools work symmetrically.
02:48
So if I do an Insert,
02:50
that's applied on both sides.
02:53
Or if I pick this edge loop and do some extrusions,
02:57
then I get the new faces built on both sides
03:00
and it's the same with the Crease tool
03:03
and most of the other subdivision tools.
03:07
And if I ever want to get rid of that forced symmetry,
03:10
I just need to use Delete Construction History
03:13
and then the sides are independent again
03:15
until I reapply symmetric modeling.
03:20
So the other method is to stick with one half like on this hood.
03:25
And you can see that I have deliberately made
03:27
this very badly lined up on the centerline.
03:30
I am pretty zig-zaggy here.
03:33
So of course, I could fix that manually with moving and snapping vertices.
03:37
But I've got a tool on the Object Edit > Align pull-down here
03:42
called Symmetry Plane Align.
03:45
So if I apply it here on this edge, both the edge CVs are snapped to the centerline
03:50
and these second CVs are moved so that they're
03:56
And these blue lines show where it's been applied.
03:60
And because it does the two CVs I can skip this edge and then do this one
04:05
and this one
04:07
to get a tidied up center edge.
04:10
And so that gives me a reasonably smooth result across the center.
04:15
And again, the wireframe is now green, so
04:18
if I pick this vertex and move it,
04:21
then construction history causes this second one to
04:23
move and maintain that 90 degree relationship.
04:29
And if I try to move the second one,
04:31
it will always ping back level to the centerline CV.
04:36
So both ways of working are equally useful,
04:39
and particularly when you use the two symmetry tools to help.
Video transcript
00:02
For a symmetrical design,
00:04
we can either build one subdivision across the centerline like this roof
00:09
or build one half and then use layer symmetry either up
00:12
here in the layer bar or here in the Object Lister.
00:17
Building the whole shape will generally give us a smoother limit surface across the center.
00:23
Building one half is generally more efficient,
00:26
but we have to work harder to get a good result on this centerline join.
00:31
There are tools that can help us with both methods,
00:34
but they all rely on the symmetry direction set in each layer.
00:38
And this yellow plane defaults to a centerline along
00:41
the X direction which works for this car,
00:44
but that can be changed, so you need to be aware of the direction
00:48
as it's this layer symmetry, which is key to using the symmetry tools.
00:54
So I'm going to start with this roof that we've built as one half.
00:58
And if we wanted now to make that the whole roof,
01:01
then I've got two ways to get the other half.
01:04
I can use Edit > Duplicate > Mirror.
01:07
And the default setting of XZ gives us
01:09
the same result as the default layer direction.
01:12
And so I get the mirrored side.
01:14
Or if I delete that
01:16
alternatively, I can turn on the layer symmetry
01:19
and then say Create Symmetric Geometry.
01:22
And the end result is exactly the same.
01:25
And I've still got two separate subdivisions
01:28
so I can join them into one using the Weld tool.
01:32
And I'm gonna use the To Tolerance setting
01:35
and just drag over these coincident center CVs to merge them.
01:40
So you can see that that's been welded into a single subdivision.
01:44
But over here, the CVs weren't snapped accurately to the center.
01:48
So I can use Weld again with two midpoints
01:51
to join those together on the centerline.
01:55
And that then gives me a reasonable smoothness across the middle.
02:01
But of course,
02:02
the difficulty is that it's very easy to make a change and lose the symmetry.
02:08
So we have a tool up here on the subdiv shelf
02:11
or here on the palette in the Object Edit tab
02:14
called Symmetric Modeling.
02:16
And if I pick the subdiv,
02:18
it reads the symmetry direction from the layer.
02:21
And when I apply it,
02:22
it forces the geometry to be symmetrical in that layer direction.
02:27
And then down here, I can choose which side to use as the master.
02:31
And you notice that the subdiv is now green, which means construction history.
02:36
So if I pick and move CVs on one side,
02:39
then the same actions are applied to the other side.
02:44
But also the subdivision tools work symmetrically.
02:48
So if I do an Insert,
02:50
that's applied on both sides.
02:53
Or if I pick this edge loop and do some extrusions,
02:57
then I get the new faces built on both sides
03:00
and it's the same with the Crease tool
03:03
and most of the other subdivision tools.
03:07
And if I ever want to get rid of that forced symmetry,
03:10
I just need to use Delete Construction History
03:13
and then the sides are independent again
03:15
until I reapply symmetric modeling.
03:20
So the other method is to stick with one half like on this hood.
03:25
And you can see that I have deliberately made
03:27
this very badly lined up on the centerline.
03:30
I am pretty zig-zaggy here.
03:33
So of course, I could fix that manually with moving and snapping vertices.
03:37
But I've got a tool on the Object Edit > Align pull-down here
03:42
called Symmetry Plane Align.
03:45
So if I apply it here on this edge, both the edge CVs are snapped to the centerline
03:50
and these second CVs are moved so that they're
03:56
And these blue lines show where it's been applied.
03:60
And because it does the two CVs I can skip this edge and then do this one
04:05
and this one
04:07
to get a tidied up center edge.
04:10
And so that gives me a reasonably smooth result across the center.
04:15
And again, the wireframe is now green, so
04:18
if I pick this vertex and move it,
04:21
then construction history causes this second one to
04:23
move and maintain that 90 degree relationship.
04:29
And if I try to move the second one,
04:31
it will always ping back level to the centerline CV.
04:36
So both ways of working are equally useful,
04:39
and particularly when you use the two symmetry tools to help.
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