# Strata proportion from DHM
<!-- <div class="algorithm-id">
<strong>Algorithm ID</strong>: <code>hedgetools:strataproportion</code>
</div> -->
```{container} algorithm-id
**Algorithm ID**: `hedgetools:strataproportion`
```

This tool takes a polygon vector layer representing hedges and a Digital Height Model (DHM) to compute the proportion of vegetation strata within the hedges. The strata bounds are user-defined.

Optionally, it can output a polygon vector layer where geometries correspond to each stratum.

```{admonition} Warning
:class: warning
Outputting the strata as a polygon vector layer doubles the processing time.
```

## Parameters

| Label | Name | Type | Description |
|-------|------|------|-------------|
| Input polygon layer | `INPUT` | [vector: polygon] | Polygon vector layer representing the hedges. |
| Input height raster (DHM) | `RASTER` | [raster] | Digital Height Model representing the height of objects above ground. |
| Height band | `BAND` | [raster band] <br> Default: 1 | Height band of the DHM raster in case of multiband. |
| Boundary for each height category | `BINS` | [string] <br> Default: 0.3, 2, 7 | Bounds for each strata. The first and last bounds are automatically appended with 0 and maximum height. For example, with the default values, the resulting strata bounds will be: **[0:0.3[, [0.3:2[, [2:7[, [7:+[**. |
| Output category as feature | `SPATIAL` | [boolean] <br> Default: False | If enabled, a spatial output will be created. |
| Output strata layer | `OUTPUT` | [vector: polygon] <br> Default: `[Create temporary layer]` | Output polygon vector layer. |
| Output category as feature (polygon) | `OUTPUT_SPATIAL` | [vector: polygon] <br> Optional <br> Default: `[Create temporary layer]` | Output polygon vector layer. |

## Outputs

| Label | Name | Type | Description |
|-------|------|------|-------------|
| Output strata layer | `OUTPUT` | [vector: polygon] | Polygon vector layer with new fields summarizing strata metrics per hedge: <ul><li>`nb_strata`: Number of strata within the hedge.</li><li>`dom_strata`: Strata covering the largest area within the hedge.</li><li>`[bound_min:bound_max[`: Occupation proportion of this strata within the hedge.</li></ul> |
| Output category as feature (polygon) | `OUTPUT_SPATIAL` | [vector: polygon] | MultiPolygon vector layer of strata. Each strata within a hedge becomes one multipolygon. The layer includes:<ul><li>`id_strata`: Index of the strata (e.g., 2 for the second strata).</li><li>`pid`: Polygon ID of the corresponding hedge.</li><li>`strata`: Height range of the strata.</li><li>`overlap`: Proportion of the hedge area occupied by this strata.</li></ul> |