Surfaces > Surface Offset
Creates an offset surface with the specified distance from the original surface. For each selected surface composite a vector handle is displayed in the graphics area to control offset distance and direction.
Offset Mode & Distance
Automatic
Creates a quick offset that allows you to specify the Deviation Tolerance. Spans are edited (added or removed) until the specific deviation tolerance is reached, or the maximum number of spans are reached.
CV Offset
The structure and parameterization of the original surface is used as input. Each CV is moved in a certain local offset direction as far as required to get the most accurate result.
Explicit
Allows you to control the degree and the number of spans for the surface offset.
Original
The surface offset is created based on the original degree and the original number of spans, but the parameterization is adapted to the new shape.
Offset Distance
Specifies the distance between the original surface and where the surface offset is created. You can specify a positive or negative Offset Distance value to create a surface offset on either side of the original surface. You can also drag the arrow head in either direction to change the Offset Distance value positively or negatively.
Explicit Control Options
Explicit Degree
Allows you to specify explicit U and V degrees for the surface offset. This option only appears if the Explicit offset mode is selected.
U Degree
Specifies the U degree for the surface offset. This option only appears if the Explicit Degree option is selected in Explicit Control Options.
V Degree
Specifies the V degree for the surface offset. This option only appears if the Explicit Degree option is selected in Explicit Control Options.
Min UV
Allows you to specify a minimum UV degree for the surface offset. This option only appears if the Explicit offset mode is selected.
Degree - Specifies the minimum UV degree for the surface offset. This option only appears if the Min UV option is selected in Explicit Control Options.
Explicit Spans
Allows you to specify explicit U and V spans for the surface offset. This option only appears if the Explicit offset mode is selected.
U Span - Specifies the U spans for the surface offset. This option only appears if the Explicit Spans option is selected in Explicit Control Options. V Span - Specifies the V spans for the surface offset. This option only appears if the Explicit Spans option is selected in Explicit Control Options.
Max UV
Allows you to specify a maximum number of UV spans for the surface offset. This option only appears if the Explicit offset mode is selected.
Spans - Specifies the maximum number of UV spans for the surface offset. This option only appears if the Max UV option is selected in Explicit Control Options.
More Options
Deviation Tolerance
Controls the accuracy of the offset result. The Deviation Tolerance option is only available if the Automatic offset mode is selected.
Min. Spans Length
Specifies the minimum length of spans for the surface offset. The Min. Spans Length option is only available if the Automatic offset mode is selected.
Shrink to Trim
Improves the reachable offset accuracy by shrinking the base of a trimmed surface. When enabled, any trimmed surface is converted to a natural surface using a trim convert operation.
Edge Accuracy
The edges of the offset result are calculated with respect to Deviation Tolerance if it is available.
Both Sides
Creates an offset surface on both sides of the original surface. The Offset values apply to both offset surfaces. The offsets of the surface cannot be controlled independently.
Create Wall
Creates closed geometry from an offset surface and the original surface. This option joins the free edges of offset surfaces to edges of the original surface. If Both Sides is enabled, creating two offset surfaces (top and bottom), the edges of these surfaces join to create the closed geometry instead of the original surface. In the Object Lister, the wall geometry appears under the Offset Wall sub-group.
Keep Continuity
An additional matching process is applied to the offset result to restore the original continuity.
The reached offset accuracy is lost in order to get better continuity.
G1/G2
Specifies the transition continuity of the surface offset.
Control Options
Auto Update
If selected, any changes in any field of the control box lead to an automatic update of the model display. Auto Update is enabled by default.
Continuity Check
Adds a continuity locator to the surface offset indicating the level of continuity.
Show Deviation
Shows the deviation of the surface offset. Show Deviation is disabled by default.
Create History
Saves the history of the curve offset so you can modify the offset later. Create History is enabled by default.
Create Metadata
Specifies whether the Curve & COS Offset tool creates history metadata. Create Metadata is enabled by default.
The Create Metadata option is available only with Autodesk Alias 2019.2 or later.
Create COS
Create Trim
Lets you specify whether or not to create a COS when applying a surface offset. Previous to Alias 2022, a COS was created by default when you applied a surface offset with this tool.
Create Trim
Lets you specify whether or not to include the trim information in the new offset surface. This option is on by default. Turning it off excludes the trim data when the offset surface is created. If the offset surface is already trimmed, you can turn off Create Trim.
Related Tasks
- Create a surface offset with Surfaces > Surface Offset
- Create a curve offset with Curves > Curve & COS Offset