Edit NURBS > Attach Surfaces


Joins two surfaces together into a single surface.

Related topics

Edit NURBS > Attach Surfaces >

Attach Method

Connect attaches the selected surfaces without distorting them.

Blend creates a continuous surface joining the original surfaces. It yields a less obvious attachment, but also might add some distortion as the blend tries to achieve continuity across the attachment.

Multiple Knots

The Multiple Knots options are used to specify whether the multiple knots at the join point are kept or removed after the attach is done.

Use Keep to keep the multiple knots created at the join point as a result of the attach. This is the default.

Use Remove to remove the multiple knots at the join point. The shape of the geometry can be changed if required.

Blend Bias

Use Blend Bias to alter the amount of continuity for the new surface; high values may distort the tangency of the original surfaces.

Insert Knot

This option is available only if you select the blend method of attachment. In conjunction with the Insert Parameter value, Insert Knot lets you make the blend region match the original surface curvature more closely.

This option has significant effect only if the original surfaces are not aligned precisely and have lengthy distances between the last two spans on each original surface near the attachment area.

Insert Knot creates two additional spans near the attachment area. Each is within one span of the points being joined from the original surfaces. You can adjust the positioning of the extra spans with the Insert Parameter value.


If you create the initial surfaces carefully, an attach usually gives the desired results without knot insertion. If you do an attach with Multiple Knots set to Remove but need more local control, you can undo and repeat the attach with Keep turned on.

Insert Parameter

This option adjusts the positioning of the spans added when you turn on Insert Knot. The closer the value is to 0 (without reaching 0), the closer the blend shape resembles the curvature of the original spans in the attachment area. This occurs because the added spans are inserted closer to the spans closest to the blend points. Valid values are from 0 to 1.

To adjust this option interactively, first create the blended surface with Insert Knot turned on. Next, select the blended surface, display the Channel Box, and select attachSurface in the INPUTS section. Try different values for Parameter until you see the desired surface curvature.

Keep Original

Retains the original surface after the attach is performed. Do not turn this option off if construction history is turned on. If you do, the attached surface might deform oddly if you manipulate it later.


  • Attach Surfaces does not work if the surfaces have the same name. Rename surfaces to have unique names prior to using Attach Surfaces

Creative Commons License Except where otherwise noted, this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License