# STAC Guidance for Metadata Creators

## STAC Guidance for Metadata Creators

This guidance is for including a STAC Catalog as a resource in a metadata record. Providing a STAC Catalog as a resource will allow GeoPlatform to discover the catalog and include it in the GeoPlatform STAC Catalog.

## STAC Background:

![](stac-guidance-for-metadata-creators/stac-catalog.png)

_The SpatioTemporal Asset Catalog (STAC) specification provides a common language to describe a range of geospatial information, so it can more easily be indexed and discovered. A 'spatiotemporal asset' is any file that represents information about the earth captured in a certain space and time._

_The STAC Specification consists of 4 semi-independent specifications. Each can be used alone, but they work best in concert with one another._

- [STAC Item](https://github.com/radiantearth/stac-spec/blob/master/item-spec/item-spec.md) is the core atomic unit, representing a single spatiotemporal asset as a [GeoJSON](https://geojson.org) feature plus datetime and links.\*
- [STAC Catalog](https://github.com/radiantearth/stac-spec/blob/master/catalog-spec/catalog-spec.md) is a simple, flexible JSON file of links that provides a structure to organize and browse STAC Items. A series of [best practices](https://github.com/radiantearth/stac-spec/blob/master/best-practices.md) helps make recommendations for creating real world STAC Catalogs.\*
- [STAC Collection](https://github.com/radiantearth/stac-spec/blob/master/collection-spec/collection-spec.md) is an extension of the STAC Catalog with additional information such as the extents, license, keywords, providers, etc that describe STAC Items that fall within the Collection.\*
- [STAC API](https://github.com/radiantearth/stac-api-spec) provides a RESTful endpoint that enables search of STAC Items, specified in [OpenAPI](https://www.openapis.org/), following [OGC's](https://www.openapis.org/) WFS 3.\*

https://stacspec.org/

## STAC Catalog as a Resource

Provide the link to the STAC Catalog as a metadata resource identifying the application profile as a SpatioTemporal Asset Catalog. The information below is from the FGDC Technical Guidance: Data.gov and [The GeoPlatform Metadata Recommendations](https://www.fgdc.gov/technical-guidance/metadata/fgdc-technical-guidance-datagov-geoplatform-ngda.pdf) in the section titled: “Provide Direct URLs to Data Download”.

### ISO 19115

Provide the download URL as either:

`MD\_Metadata.identificationInfo>MD\_DataIdentification.citation>CI\_Citation.citedResponsibleParty>CI\_ResponsibleParty. contactInfo>CI\_Contact.onlineResource>CI\_OnlineResource.linkage`

or

`MD\_Metadata.distributionInfo>MD\_Distribution.transferOptions>MD\_DigitalTransferOptions.onLine>CI\_OnlineResource.linkage`

Provide the download file name as either:`

`MD\_Metadata.identificationInfo>MD\_DataIdentification.citation>CI\_Citation.citedResponsibleParty>CI\_ResponsibleParty. contactInfo>CI\_Contact.onlineResource>CI\_OnlineResource.name`

or

`MD\_Metadata.distributionInfo>MD\_Distribution.transferOptions>MD\_DigitalTransferOptions.onLine>CI\_OnlineResource.name`

Provide a description of the download resource to give consumers much needed context for the URL as either:

`MD\_Metadata.identificationInfo>MD\_DataIdentification.citation>CI\_Citation.citedResponsibleParty>CI\_ResponsibleParty. contactInfo>CI\_Contact.onlineResource>CI\_OnlineResource.description`

or

`MD\_Metadata.distributionInfo>MD\_Distribution.transferOptions>MD\_DigitalTransferOptions.onLine>CI\_OnlineResource.description`

Indicate the format of the download as a SpatioTemporal Asset Catalog:

`MD\_Metadata.identificationInfo>MD\_DataIdentification.citation>CI\_Citation.citedResponsibleParty>CI\_ResponsibleParty. contactInfo>CI\_Contact.onlineResource>CI\_OnlineResource.applicationProfile`

or

`MD\_Metadata.distributionInfo>MD\_Distribution.transferOptions>MD\_DigitalTransferOptions.onLine> CI\_OnlineResource.applicationProfile`

## Example using the Landsat STAC Catalog

```
<gmd:CD_OnlineResource>
  <gmd:linkage>
    <gmd:URL>https://landsat-stac.s3.amazonaws.com/catalog.json</gmd:URL>
  </gmd:linkage>
  <gmd:protocol>
    <gco:CharacterString>STAC</gco:CharacterString>
  </gmd:protocol>
  <gmd:applicationProfile>
    <gco:CharacterString>SpatioTemporal Asset Catalog</gco:CharacterString>
  </gmd:applicationProfile>
  <gmd:name>
    <gco:CharacterString>Landsat STAC Catalog</gco:CharacterString>
  </gmd:name>
  <gmd:description>
    <gco:CharacterString>SpatioTemporal Asset Catalog for Landstat Data</gco:CharacterString>
  </gmd:description>
<gmd:CI_OnlineResource>
```

## More information

- [SpatioTemporal Asset Catalogs](https://stacspec.org/)
- [Introduction to STAC](https://developers.planet.com/planetschool/introduction-to-stac-part-1-an-overview-of-the-specification/)
- [FGDC Technical Guidance: Data.gov and The GeoPlatform Metadata Recommendations](https://www.fgdc.gov/technical-guidance/metadata/fgdc-technical-guidance-datagov-geoplatform-ngda.pdf)