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

# Elevation & Surface

> Add elevation data and surface type information to your routes

The Elevation & Surface tool adds two types of data to your tracks: elevation profiles from terrain data and surface types from OpenStreetMap.

## Elevation Data

Elevation data is essential for:

* Calculating total ascent and descent
* Viewing accurate elevation profiles
* Planning routes based on terrain difficulty
* Transferring routes to GPS devices that display elevation

### Adding Elevation

1. Select a track or waypoint in the [File Tree](/docs/app/file-tree)
2. Open the Elevation & Surface tool
3. Click **Add Elevation Data**

The tool updates:

* All GPS points in selected tracks
* Selected [waypoints](/docs/tools/waypoints)

### Elevation Data Source

<Note>
  Elevation data is provided by [Mapbox](https://mapbox.com). You can learn more about its origin and accuracy in the [Mapbox Terrain documentation](https://docs.mapbox.com/data/tilesets/reference/mapbox-terrain-dem-v1/#elevation-data).
</Note>

### When to Use Elevation

* **Manually drawn routes** - Routes created with the [Route Planning](/docs/tools/route-planning) tool may not have elevation data
* **Imported routes** - Some GPX files lack elevation information
* **Inaccurate GPS elevation** - Barometric or GPS-based elevation can be noisy; terrain data provides a cleaner profile

## Surface Data

Surface data tells you what type of terrain your route passes over - paved roads, gravel paths, dirt trails, etc. This is invaluable for planning rides and understanding route difficulty.

Surface information comes from [OpenStreetMap](https://www.openstreetmap.org) and is matched to your track by routing along it. Rendzo reads the OSM `surface` tag where it exists, and estimates the rest from the road type.

### Adding Surface Data

1. Select a track, segment, or file in the [File Tree](/docs/app/file-tree)
2. Click **Request Surface Data**

A movable panel opens and the surfaces appear **live on the map and the [elevation profile](/docs/app/elevation)**, with the base track dimmed so the colors stand out. **Nothing is saved until you press Apply**, so you can review everything first.

<Note>
  The panel floats over the map, so you can keep panning and zooming while you review. Hovering along the track shows the exact surface under your cursor.
</Note>

### Reviewing the Results

The panel walks you through what Rendzo data matching found, with confidence made explicit:

* **Coverage** is shown at the top: how much surface data came directly from OpenStreetMap, how much was estimated from the road type, and how much remains unknown. A per-surface breakdown bar shows the mix (asphalt vs. gravel vs. dirt, etc.).
* **Roads OpenStreetMap didn't tag** are listed below - only the road types actually present in your selection that lack an OSM surface. Each row shows the road type, a point count, a color swatch, and a dropdown pre-filled with a smart default.
* Changing any dropdown **recolors the map and profile instantly** - no re-fetch, no waiting.

### Smart Defaults for Untagged Roads

When OpenStreetMap doesn't tag a road's surface, Rendzo fills in a best guess from the road type - and, where OSM provides a `tracktype` grade, it picks a more specific guess:

| Track grade | Estimated surface |
| ----------- | ----------------- |
| grade1      | Compacted         |
| grade2      | Fine gravel       |
| grade3      | Gravel            |
| grade4      | Dirt              |
| grade5      | Ground            |

Off-road road types like tracks, paths, and bridleways default to **unpaved** rather than being lumped in with asphalt. You can override any of these from the dropdowns, and **Reset to defaults** restores Rendzo's recommended values at any time.

### Applying and Viewing Surface Data

Press **Apply** to write the surface data to your file, or **Cancel** to discard the preview. Once applied, you can:

* View the surface breakdown in your route statistics
* See surface types color-coded on the [elevation profile](/docs/app/elevation)
* Turn on the surface map overlay (see below)
* Export the data with your GPX file

### Show Surface on the Map

Turn on **View → Surface** (<kbd>F9</kbd>) to color **every visible track** by its surface - independently of the surface tool and the elevation profile. Hover any colored track to read the surface under your cursor. Tracks that don't have surface data yet keep their normal color; run **Request Surface Data** on them to fill it in.

<Note>
  Surface data quality depends on OpenStreetMap coverage in your area. Well-mapped regions are near-complete, while remote tracks rely more on the road-type estimate.
</Note>