# Relative orientation
<!-- <div class="algorithm-id">
<strong>Algorithm ID</strong>: <code>hedgetools:relativeorientation</code>
</div> -->
```{container} algorithm-id
**Algorithm ID**: `hedgetools:relativeorientation`
```

This tool computes the relative orientation of hedges within the main slope. It calculates the difference between the hedge median axis orientation and the slope exposition derived from the given DTM, and categorizes hedges into four categories: no slope, perpendicular to the slope, parallel to the slope, or diagonal to the slope.

```{note}
It is recommended not to use a DTM with very high resolution, as it may create numerous small topographic variations, introducing noise in the results.
```

## Parameters

| Label | Name | Type | Description |
|-------|------|------|-------------|
| Input polygon layer | `INPUT_POLYGON` | [vector: polygon] | Polygon vector layer. |
| Input arc layer | `INPUT_ARC` | [vector: line] | Line vector layer representing the median axis of the polygons. |
| Input elevation raster (DTM) | `RASTER` | [raster] | Digital Terrain Model describing the ground elevation without obstacles. |
| Elevation band | `BAND` | [raster band] <br> Default: 1 | Elevation band of the DTM raster in case of multiband. |
| Kernel size (pixels) | `KERNEL_SIZE` | [numeric: integer] <br> Default: 7 | Size of the kernel for applying the Gaussian filter on the DTM. Must be odd. Larger kernels provide more smoothing (i.e remove more noise). |
| Tolerance (°) | `TOLERANCE` | [numeric: integer] <br> Default: 15 | Maximum deviation, in degrees, to consider a hedge perpendicular or parallel to the slope. For example, with 15° tolerance: perpendicular is 75°–105°, parallel is 165°–195°. |
| Minimum slope (%) | `MIN_SLOPE` | [numeric: double] <br> Default: 50.0 | Hedges with slope below this value are automatically categorized as "no slope." May be imprecise for valleys or narrow ridges. |
| Use topographic position for no slope category | `USE_GEOMORPHON` | [boolean] <br> Default: True | Use the [topographic position](topographic_position.md) algorithm to classify hedges in valleys or ridges as "no slope." |
| Search radius (meters) | `SEARCH` | [numeric: integer] <br> Default: 100 | Maximum distance around each cell used by the geomorphon algorithm to define the surrounding topography. |
| Skip radius (meters) | `SKIP` | [numeric: integer] <br> Default: 0 | Distance used by the topography algorithm to ignore small irregularities when constructing topographic forms. |
| Output relative orientation layer | `OUTPUT` | [vector: polygon] <br> Default: `[Create temporary layer]` | Output polygon vector layer. |

## Outputs

| Label | Name | Type | Description |
|-------|------|------|-------------|
| Output relative orientation layer | `OUTPUT` | [vector: polygon] | Polygon vector layer with a new field `slope_position`, indicating the relative orientation of hedges to the slope. |