& Construction

Integrated BIM tools, including Revit, AutoCAD, and Civil 3D
& Manufacturing

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
In Alias, we can create smooth NURBS models
00:05
using subdivision modeling techniques.
00:09
A subdivision object has an orange wire frame
00:12
but sometimes it will be shown green if it's got construction history
00:15
like Symmetry Align here.
00:19
The individual patches are known as limit surfaces
00:22
and we don't manipulate these directly.
00:24
Instead we use the subdivision control cage
00:28
that I can show with this box shading mode
00:30
and manipulate by turning on the control vertices.
00:35
And then I can use the normal Selection and Transform tools
00:39
to shape the subdivision either in the box shading
00:42
or more typically with surface shading.
00:45
And you can see that all the limit surfaces update and stay connected and smooth.
00:51
And because these are NURBS surfaces, I can create a hybrid model.
00:56
So you can maintain the simplicity of the SubD control cage
01:00
but also use traditional NURBS trimming and surface tools.
01:05
So here I've projected curves and trimmed holes in the limit surfaces
01:09
and added a surface filet
01:11
and the same up here
01:13
all with history and without affecting or over-complicating the SubD topology.
01:19
So you can present a finished design but keep the subdivision model easy to change.
01:26
And the topology of the control cage is key
01:28
to sculpting more complex shapes like this car.
01:32
So we're generally aiming for quads where possible
01:35
with a good flow in both directions.
01:38
But we do have the flexibility with subdivisions to use star
01:41
points like these five edges coming into one point here,
01:45
and n-gons like this five sided one
01:48
and three sides down here.
01:51
And this thicker edge is a crease on the subdivision cage
01:55
which gives a sharp edge on the limit surfaces.
01:59
So if I check the G2 curvature continuity,
02:02
all the non-creased surfaces are smoothly connected.
02:06
And where a crease is specified, you get G0 position continuity.
02:13
You won't get production quality highlights,
02:15
but you do maintain a smooth coherent object as you make changes.
02:20
And this means that you can focus on shaping
02:22
your design by moving the control cage vertices.
02:26
And the subdivision math does all the work
02:28
of keeping those limit surfaces smooth and connected,
02:31
which is a big time-saver around tricky blended areas like this wheel arch.
Video transcript
00:02
In Alias, we can create smooth NURBS models
00:05
using subdivision modeling techniques.
00:09
A subdivision object has an orange wire frame
00:12
but sometimes it will be shown green if it's got construction history
00:15
like Symmetry Align here.
00:19
The individual patches are known as limit surfaces
00:22
and we don't manipulate these directly.
00:24
Instead we use the subdivision control cage
00:28
that I can show with this box shading mode
00:30
and manipulate by turning on the control vertices.
00:35
And then I can use the normal Selection and Transform tools
00:39
to shape the subdivision either in the box shading
00:42
or more typically with surface shading.
00:45
And you can see that all the limit surfaces update and stay connected and smooth.
00:51
And because these are NURBS surfaces, I can create a hybrid model.
00:56
So you can maintain the simplicity of the SubD control cage
01:00
but also use traditional NURBS trimming and surface tools.
01:05
So here I've projected curves and trimmed holes in the limit surfaces
01:09
and added a surface filet
01:11
and the same up here
01:13
all with history and without affecting or over-complicating the SubD topology.
01:19
So you can present a finished design but keep the subdivision model easy to change.
01:26
And the topology of the control cage is key
01:28
to sculpting more complex shapes like this car.
01:32
So we're generally aiming for quads where possible
01:35
with a good flow in both directions.
01:38
But we do have the flexibility with subdivisions to use star
01:41
points like these five edges coming into one point here,
01:45
and n-gons like this five sided one
01:48
and three sides down here.
01:51
And this thicker edge is a crease on the subdivision cage
01:55
which gives a sharp edge on the limit surfaces.
01:59
So if I check the G2 curvature continuity,
02:02
all the non-creased surfaces are smoothly connected.
02:06
And where a crease is specified, you get G0 position continuity.
02:13
You won't get production quality highlights,
02:15
but you do maintain a smooth coherent object as you make changes.
02:20
And this means that you can focus on shaping
02:22
your design by moving the control cage vertices.
02:26
And the subdivision math does all the work
02:28
of keeping those limit surfaces smooth and connected,
02:31
which is a big time-saver around tricky blended areas like this wheel arch.
How to buy
Privacy | Do not sell or share my personal information | Cookie preferences | Report noncompliance | Terms of use | Legal | © 2025 Autodesk Inc. All rights reserved
Sign in to start learning
Sign in for unlimited free access to all learning content.Save your progress
Take assessments
Receive personalized recommendations
May we collect and use your data?
Learn more about the Third Party Services we use and our Privacy Statement.May we collect and use your data to tailor your experience?
Explore the benefits of a customized experience by managing your privacy settings for this site or visit our Privacy Statement to learn more about your options.