> For the complete documentation index, see [llms.txt](https://docs.imerit.net/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.imerit.net/labeling/labeling-tools/tools/polyline.md).
# Polyline
The polyline labeling tool allows you to draw a line on an image.
{% hint style="info" %}
The Polyline tool is supported across the Image, Video, DICOM, and Medical labeling editors.
{% endhint %}
## The Polyline Labeling Tool in Ango Hub
### How to add a Polyline tool to your project
From the project’s *Settings* tab, enter the *Label Set* section.
Click on *Add Category*. From the list that appears, click on *Polyline*.
A new row will appear named *Polyline*. Click on it to expand it.
Give your polyline tool a title and description.
Enable the *Required* toggle if you want to force labelers to create a polyline on every asset. When the toggle is disabled, labelers will be able to save and move to the next asset without creating a polyline label using this class.
If you would like to ask labelers further questions, for example, if you want to show a further *radio* after drawing the polyline, click on *Add Classification* and add a further question. More[ on nested questions here](/labeling/labeling-tools/tools/nested-classifications.md).
### How to Draw a Polyline
Click on the image where you’d like the first point of the polyline to be. Click again where you’d like the second point to be, and so on. When you are done, press *N* on your keyboard to finish the polyline.
While drawing, you may click anywhere with the right mouse button to delete the last point you have placed.
To edit a polyline's points, select it by clicking on it, then drag the polyline itself or one of its points.
## Edge Sharing
While drawing a polyline, if you press E, Hub will highlight the points of other polygons, polylines, and points. By clicking on the other object's points, you can snap your current polyline's points to them:
By snapping at least two points to the existing polygon and holding Alt (⌥ on macOS) + clicking, you can quickly anchor a series of points to the existing object, as shown in the GIF above.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.imerit.net/labeling/labeling-tools/tools/polyline.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.