# Simplify arc
<!-- <div class="algorithm-id">
<strong>Algorithm ID</strong>: <code>hedgetools:simplifyarc</code>
</div> -->
```{container} algorithm-id
**Algorithm ID**: `hedgetools:simplifyarc`
```

The median axis generated by the [topological arc](topological_arc.md) may not meet user requirements.
This tool offers simplification using the Douglas-Peucker algorithm constrained by the enclosing polygon. This allows for the removal of median axis irregularities while ensuring its inclusion within the hedge extent. However, the centrality of the median axis is lost. This treatment can be useful for more reliably estimating hedge length.

```{container} slider-parameter

Shift tolerance (meters):
```
```{raw} html
<div class="slider-row">
  <div class="slider-row-inner">
    <span class="slider-value" id="simplifyValue"">0</span>
    <input type="range" id="simplify" min="0" max="20" step="5" value="0">
  </div>
</div>

<img  class="slider" id="simplifyImage" src="">
```
```{admonition} Explanation
:class: remarque
The initial image shows the median axis. As the shift tolerance increases, the median axis becomes less irregular.
```

## Parameters

| Label | Name | Type | Description |
|-------|------|------|-------------|
| Input arc layer | `INPUT_ARC` | [vector: line] | Line vector layer to be simplified. |
| Input polygon layer | `INPUT_POLY` | [vector: polygon] | Polygon vector layer enclosing the line layer. |
| Shift tolerance (meters) | `TOLERANCE` | [numeric: double] <br> Default: 1.0 | Maximum allowed shift of the line during simplification. |
| Output simplified layer | `OUTPUT_ARC` | [vector: line] <br> Default: `[Create temporary layer]` | Output line vector layer. |

## Outputs

| Label | Name | Type | Description |
|-------|------|------|-------------|
| Output simplified layer | `OUTPUT_ARC` | [vector: line] | Simplified line vector layer. In some cases, the line cannot be simplified and the original geometry is returned. |