---
title: "Join 2 Polylines"
slug: "cyclone-3dr-joinpolylinesc"
updated: 2026-09-07T11:51:38Z
published: 2026-09-07T11:51:38Z
canonical: "rcdocs.leica-geosystems.com/cyclone-3dr-joinpolylinesc"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://rcdocs.leica-geosystems.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Join 2 Polylines

![CmdJoinTwoPolylines.svg](https://cdn.document360.io/820e11db-8ed5-45ae-ac86-f6b77dcb2aa7/Images/Documentation/CmdJoinTwoPolylines.svg)

This command computes a curve to make the junction between two polylines.

> [!TIP]
> ### Requirements
> 
> No selection is required to launch the command.

---

1. **Click the two extremities** of polylines to be joined.
2. A default junction is computed and you can see a polygon with some **control points** on each vertex. These control points can be used to adjust the junction shape. Click one of the control points and **drag it** to modify the shape.
  - The first and last extremity direction fixes the starting and ending junction direction. Note the tangency is not only computed with the last segment of each extremity. In some cases, you could have to resample one or both input polylines before.
  - The first and last segment length + the central ball modify the curvature of the bridge.
3. If the two segments on each side of the junction are not parallel, the junction may be non-planar. If needed you can force to **make a planar junction**. In this case, the plane will be computed using both extremities and the middle control point.
4. Select the option **Chain all the parts** to merge the three pieces into one polyline (the two initial polylines + the junction), or select **Build junction only** to keep three independent parts.

> [!TIP]
> ### Tips & Tricks
> 
> You can also make a junction between two free surface borders with the [Bridge](/v1/docs/cyclone-3dr-bridgec) command.