# Curves

Create and edit 3D curves by extending, rebuilding, intersecting, splitting, and projecting the shapes.

Create and edit 3D curves by extending, rebuilding, intersecting, splitting, and projecting the shapes.

**NURBS**

Create and edit a NURBS curve, which is a free-form curve.**Blend**

Create and edit a free-form curve that blends into one or more existing curves, surfaces, or edges.**On Surface**

Create and edit a blend curve directly on one or more surfaces.**Freeform Circle/Arc**

Create and edit a free-form circle or arc.**Rounded Polyline**

Draw a sequence of straight and/or rounded lines.**3D Line**

Create a straight line in planar or non-planar 3D space. The line can be free in 3D space, tangent to a source curve, perpendicular to a source curve, normal to the plane in which a source curve lies, fixed to a source curve at one end, or combined with a source curve. The source curve can be an individual curve or the edge of a surface.**Rectangle**

Create and edit a rectangle or square.**Helix**

Create a helix (or a spiral if the top and bottom radii are different).**Offset**

Create a copy of one or more curves at a specified distance from the source curves. This tool can be used on both 2D and 3D curves.**Extend**

Extend a curve and edit the extension.**Rebuild**

Rebuild one or more curves by changing the number of control points, joining multiple curves, or inverting the sequence of the control points.**Split**

Create trimmed curves by using a set of tool curves to split a set of target curves, keeping only the desired pieces. You can use this tool to split one self-intersecting curve into multiple pieces.**Divide**

Divide a curve into several independent curves.**Section Curves**

Create an object containing the section curves of a NURBS surface object. You can specify the direction and the position of the section planes as well as the number of the planes and the distance between them. This modeling tool maintains construction history.**Edge Extract**

Extract curves or edges from one or more objects, making the result a separate, selectable object.**Projection**

Project one or more curves onto one or more surfaces in a specified direction.**From Surface Intersection**

Extract a curve from the intersection of two surfaces.**Extract Isoparms**

Extract isoparametric curves from a surface in the U or V direction. This is useful for creating trim curves that run along a surface but are not attached to it.**Silhouette**

Extract the 2D or 3D silhouette curve of one or more selected objects while maintaining construction history.