# Asset

```python
class Asset(
    key: str,
    primary: AssetLocation,
    alternates: Mapping[str, AssetLocation] = {},
    media_type: MediaType | str | None = None,
    title: str | None = None,
    description: str | None = None,
    roles: frozenset[KnownAssetRole | str] = frozenset(),
    gsd: float | None = None,
    bands: tuple[Band, ...] = (),
    data_type: DataType = DataType.UNSPECIFIED,
    nodata: float | None = None,
    statistics: Statistics | None = None,
    unit: str | None = None,
    eo: EOProperties | None = None,
    raster: RasterProperties | None = None,
    projection: Projection | None = None,
    view: View | None = None,
    classes: tuple[ClassificationClass, ...] = (),
    file: File | None = None,
    sar: SARProperties | None = None,
    satellite: SatelliteProperties | None = None,
    product: ProductProperties | None = None,
)
```

Describe an asset and its primary and alternate locations.

## Fields

**key**

`str`

The asset's unique key within its datapoint.

**primary**

`AssetLocation`

The primary asset location.

**alternates**

`Mapping[str, AssetLocation]`

Alternate locations keyed by their STAC alternate-assets key.

**media\_type**

`MediaType | str | None`

The exact media type.

**roles**

`frozenset[KnownAssetRole | str]`

Known or custom STAC asset roles.

**bands**

`tuple[Band, ...]`

Ordered band metadata.

The other fields contain optional STAC metadata defined by extensions such as [Electro-Optical](https://github.com/stac-extensions/eo), [Projection](https://github.com/stac-extensions/projection), and [Raster](https://github.com/stac-extensions/raster).

## Media types

Import `MediaType` with the authoring types from `tilebox.datasets.assets`. Its members are strings, such as `MediaType.GEOTIFF`, `MediaType.CLOUD_OPTIMIZED_GEOTIFF`, `MediaType.PNG`, and `MediaType.NETCDF`. You can also pass a custom media type string.

```python title="Python"
from tilebox.datasets.assets import Asset, AssetLocation, MediaType

asset = Asset(
    key="image",
    primary=AssetLocation("s3://bucket/image.tif"),
    media_type=MediaType.CLOUD_OPTIMIZED_GEOTIFF,
)
```