Tool Palettes Object edit > Extend > Options

Object edit > Extend

Extends a curve or surface beyond its current endpoint or edge by adding new geometry.

See Extend the ends/edges of a curve or surface

Tips and notes

The three types of extension can produce very different results.
The Merge option creates a multi-knot at the connection point for Linear and Circular extensions. Curves with multi-knots may not be usable as construction curves, and CAD packages cannot import them.

Options

Linear

Extend the curve or surface in a straight line.

Because this extension is linear and has no curvature, there is usually a curvature discontinuity at the point or edge where the geometry was extended.

Circular

Extend the curve or surface along an arc.

This extension has have a constant curvature, equal to the curvature at the point or edge where the geometry was extended.

Extrapolate

Extend the curve or surface with the same rate of change in curvature as at the endpoint or edge.

This option produces the smoothest and most seamless extension without adding any edit points to the original surface.

To fix rough rendering that may result, increase the subdivisions in Render > Editors > Render stats .

Merge

Merge the extended part with the original surface to form one object. It is turned on by default.

Chain Select

If this option is checked, you can select a series of tangent continuous surface edges by clicking on any one of them.

Distance

Default length or angle of the extension when it is first created.

For Linear and Extrapolate extensions, Distance is expressed in the current linear unit. For Circular extensions, it is expressed in the current angular unit. This option is originally set to 0.0.