STAC assets

Overview

A STAC asset is a geospatial feature of a STAC item. For example, bands in an optical image, thumbnails, and metadata files represent different STAC assets.

The cloud-native asset model (CNAM) format transforms an UP42 asset into individual geospatial features available for immediate download. Regardless of provider or delivery format, UP42 transforms assets into a standard model. CNAM also standardizes the following types of files to enable easier integrations:

Raster data is converted into cloud optimized GeoTIFFs (COGs).
Vector mask files are converted into GeoJSONs.

Elements of the originally delivered UP42 asset are mapped as individual STAC assets on a STAC item level. Original delivery is mapped as a STAC asset on a STAC collection level.

A diagram showing UP42 assets are mapped on a STAC collection level, and STAC assets are mapped in a STAC item level

You can also access CNAM files using the console.

STAC assets in a STAC item

STAC assets are returned as part of a STAC item response body. You can get STAC assets in one of the following ways:

By requesting a list of all STAC items from a particular STAC collection.
By requesting a particular STAC item.
By making a detailed STAC item search request.

JSON

    {
  <...>,
  "assets": {
    "mgag5ui3_img_phr1a_ms_202208080011285_sen_6452562101-2.tiff": {
      "href": "https://api.up42.com/v2/assets/e4a15000-890b-445c-82bb-e4364baac40b",
      "title": "Multispectral data",
      "type": "image/tiff; application=geotiff; profile=cloud-optimized",
      "roles": ["data", "multispectral"],
      "gsd": 0.7283,
      "eo:bands": [
        {
          "name": "blue",
          "common_name": "blue",
          "center_wavelength": 0.47,
          "full_width_half_max": 0.07
        },
        {
          "name": "green",
          "common_name": "green",
          "center_wavelength": 0.47,
          "full_width_half_max": 0.07
        },
        {
          "name": "red",
          "common_name": "red",
          "center_wavelength": 0.665,
          "full_width_half_max": 0.038
        }
      ]
    }
  },
  <...>
}

Parameter	Overview
`href`	string The URL of a downloadable or a streamable file related to the STAC asset.
`title`	string The STAC asset title.
`type`	string The STAC asset media type.
`roles`	array of strings The role of the STAC asset.
`gsd`	float The ground sample distance, in meters.
`eo:bands`	array of objects Electro-optical bands. For more information, see extension specification.
	Parameters of the `eo:bands` array
`name`	string The name of the band.
`common_name`	string The name commonly used to refer to the band to make it easier to search for bands. For more information, see the list of common band names.
`center_wavelength`	float The center wavelength of the band, in micrometers.
`full_width_half_max`	float Full width at half maximum. The width of the band, as measured at half the maximum transmission, in micrometers.

Roles

Data

Role	Description
`data`	A higher-level role for all types of data. The CNAM format transforms all raster assets with the `data` role into COGs.
`multispectral`	An asset related to the multispectral band.
`panchromatic`	An asset related to the panchromatic band.

Metadata

Role	Description
`metadata`	A higher-level role for all types of metadata.
`bundle`	Delivery metadata that contains information about both types of bands, panchromatic and multispectral.
`extended`	Detailed metadata for multispectral and panchromatic bands.
`iso-19115`	ISO 19115-1:2014 metadata.
`license`	An end-user license agreement (EULA).
`lineage`	Processing, ground, or strip lineage.
`lut`	A Look-Up-Table with rendering of color curves in a reflectance product.
`quality-elevation`	Quality elevation metadata.
`stac`	STAC-related metadata.
`stereo`	Stereo metadata.
`tile-info`	Tiling metadata.
`toa-factors`	Top-of-atmosphere reflectance metadata.
`angle`	Sensor viewing angle model coefficients.
`digest`	Digest metadata.
`auxiliary`	Auxiliary metadata.

Previews

Role	Description
`overview`	A preview image of higher resolution than `thumbnail`.
`thumbnail`	A low-resolution preview image, usually up to 600×600 px.
`visual`	A full-resolution version of the data, processed for visual use.

Masks

Role	Description
`data-mask`	A higher-level role for all types of masks. The CNAM format transforms all vector assets with the `data-mask` role into GeoJSON files.
`cloud`	A cloud mask. If an asset has cloud coverage of 5% or lower, cloud masks won’t be provided.
`detector-quality`	A quality detector mask.
`footprint`	A footprint.
`roi`	A region of interest mask.
`saturation`	A saturation mask.
`technical-index`	A technical index mask.
`visibility`	A visibility mask.
`water-mask`	A water detection mask.
`cloud-shadow`	A cloud shadow detection mask.
`snow-ice`	A snow and ice detection mask.

Other

Role	Description
`index`	Spectral indexes.
`rpc`	Rational polynomial coefficients.
`temperature`	A surface temperature band.
`emissivity`	An emissivity band.

Limitations

CNAM is only available for assets added to storage starting in 2023.

Not all geospatial collections are supported. To get a list of supported collections, see Introduction to STAC.