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

# Satellite Imagery

> Sentinel-2 and Planet Labs imagery with band math

# Satellite Imagery

agronome.ai provides satellite imagery for every field with a defined boundary. View vegetation health indices, track changes over time, and compare aerial and satellite perspectives.

## Data sources

### Sentinel-2

Free, open-access imagery from the European Space Agency's Copernicus program.

* **Resolution:** 10m (visible bands), 20m (Red Edge, NIR, SWIR)
* **Revisit:** Every 5 days
* **Coverage:** Global
* **Cost:** Free

Sentinel-2 imagery is available immediately for any field. No setup required.

### Planet Labs

Commercial high-resolution imagery (requires subscription).

* **Resolution:** 3m (PlanetScope), 50cm (SkySat)
* **Revisit:** Daily (PlanetScope)
* **Coverage:** Global
* **Cost:** Subscription-based

Planet imagery requires connecting your Planet Labs account in Settings → Integrations.

## Available layers

| Layer             | Bands                     | What it shows                                          |
| ----------------- | ------------------------- | ------------------------------------------------------ |
| **Natural Color** | RGB                       | True-color aerial view                                 |
| **NDVI**          | (NIR - Red) / (NIR + Red) | Vegetation health and density                          |
| **EVI**           | Enhanced vegetation index | Vegetation health in dense canopy                      |
| **CIR**           | NIR, Red, Green           | Color infrared — healthy vegetation appears bright red |

## Viewing imagery

1. Navigate to a field's **Analyze** tab
2. Select a date from the timeline
3. Choose a layer type (Natural Color, NDVI, EVI, CIR)
4. Use the opacity slider to compare with the base map

## Tile caching

Satellite tiles are cached in two layers for performance:

1. **Redis** — hot cache for recently viewed tiles (TTL-based)
2. **Google Cloud Storage** — persistent cache for all requested tiles

First-time tile requests fetch from the upstream provider (Sentinel Hub). Subsequent requests serve from cache with no upstream call.