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

# Arrow Tool

> Place directional markers on the 3D view to indicate approach paths

## What Are Arrows?

Arrows are directional markers placed on the 3D volume to indicate a direction of approach — for example, the path along which an instrument would travel toward a target. Each arrow has a **tail** (starting point) and a **head** (endpoint), with the arrowhead indicating direction.

<img src="https://mintlify.s3.us-west-1.amazonaws.com/altician/images/arrow-placed.png" alt="Arrow placed on 3D volume" />

## Activation

Click the **Arrow** button in the toolbar to activate the Arrow tool.

## Creating an Arrow

1. Click on the volume to place the **tail** (starting point).
2. Click again to place the **head** (endpoint and direction).
3. The arrow appears immediately in the 3D view.

Multiple arrows can be placed. Each arrow is listed in the right panel under **Arrows**.

## Editing an Arrow

| Action          | How                                                  |
| --------------- | ---------------------------------------------------- |
| Move the tail   | Drag the tail endpoint                               |
| Move the head   | Drag the arrowhead                                   |
| Delete an arrow | Select it in the panel, then click the delete button |
| Rename an arrow | Double-click the label in the panel                  |

## Visibility Toggle

Click the eye icon next to any arrow in the right panel to show or hide it individually. This is useful when multiple arrows are present and you want to focus on one at a time.

## Viewport Synchronization

Arrows are displayed in both the **main viewport** and the **Scouter** viewport simultaneously. Any change (position, visibility) is reflected in both views instantly.

## Using Arrows with Endoscope

When the Endoscope is active, you can align the camera along an arrow's direction:

1. Place an arrow indicating the desired approach direction.
2. In the Endoscope panel, select the arrow from the **Align to Arrow** dropdown.
3. The endoscope camera repositions to match the arrow's trajectory.

<Note>
  Arrows are saved with the session. If you reload the file, arrows will need to be re-placed.
</Note>

<Warning>
  Activating the Arrow tool automatically deactivates **W/L** and **Ruler**. Only one interaction tool can be active at a time.
</Warning>