v1.1.0

Version 1.1.0 is the first stable release after the 1.0.0 release of the SpatioTemporal Asset Catalog specification!

The focus has been the addition of a common band construct to unify eo:bands and raster:bands.
Additionally, Item Asset Definitions are now part of the core specification and various additional fields have been made available via the common metadata mechanism.
Some alignment with OGC API - Records have been integrated and the best practices have evolved further.
It is accompanied by various minor changes and clarifications.

Changes since v1.1.0-beta.1

Added

• Add to best-practices mime types for COPC, Geoparquet, 3dTiles, pmtiles (#1321)

Fixed

• item_assets is not required
• Better describe the Statistics Object (#1318)
• bands as entity in UML model
• Editorial edits

Changes since v1.0.0

Added

• bands is a new field in common metadata to replace eo:bands and raster:bands (#1213)
• The fields data_type, nodata, statistics and unit have been added to common metadata (#1213)
• The keywords field known from Collections is available in common metadata. (#1187)
• New fields method, headers and body in the Link Object. (#1198)
• The license field additionally supports SPDX expressions and the value other.
• The roles field known from Assets and Providers is available in common metadata. (#1267)
• The collection relation type is added to the list of known relation types. (#1236)
• The item_assets field in Collections are integrated from extension into the core Collection spec. (#1275)
• Validation for absolute self link in item schema. (#1281)
• Best practice: Link titles should exactly reflect the title of the corresponding entity (#1168)

Changed

• Common Metadata:
  • Clarify in various field descriptions that the fields do not only apply to Items
  • Validate the fields also in Catalogs, Collections and Links
  • If a description is given, require that it is not empty
• Clarified URL resolving mechanics, e.g. that trailing slashes in URLs are significant (#1212)
• All JSON Schema $id values no longer have # at the end.
• Two spatial bounding boxes in a Collection don't make sense and will be reported as invalid by the schema. (#1243)
• Clarify in descriptions that start_datetime and end_datetime are inclusive bounds (#1280)
• Moved the STAC structural relations into commons
• Moved general descriptions about Assets and Links into commons
• Moved common metadata from the item-spec into commons, but kept the JSON schemas in the item-spec for backward compatibility

Deprecated

• license: The values proprietary and various are deprecated in favor of SPDX expressions and other.

Removed

• "Strongly recommended" language around self links in the item spec. (#1173)

Fixed

• Several typos and minor language changes
• Clarification on unique parent link requirement (#1279)
• Clarified that collection IDs should be unique across all collections in the corresponding root catalog
• Clarified that item IDs should be unique per collection
• Clarified which media types should be used for the hierarchical relation types
• Clarified in the Markdown specification that GeometryCollections are not allowed as Item Geometry (#1160)
• Best practice: Do not recommend subdirectories for Items without sidecar files (#1195)
• Clarified that multiple collections can point to an Item, but an Item can only point back to a single collection. (#1273)
• Restructured asset role types and clarified usage of the roles thumbnail, overview and visual (#1272)
• Clarified that JSON Schema draft-07 is the default version for Collection summaries and other versions may not be supported

Thanks Contributors @m-mohr @gadomski @emmanuelmathot @philvarner @sankichi92 @christophfriedrich @dwsilk @matthewhanson @cholmes @wilsaj @tschaub @jonhealy1 @nkleinbaer @jedsundwall @jbants

v1.1.0-beta.1

Version 1.1.0-beta.1 is the first update to the stable release of the SpatioTemporal Asset Catalog specification!

The focus has been the addition of a common band construct to unify eo:bands and raster:bands.
Additionally, Item Asset Definitions are now part of the core specification and various additional fields have been made available via the common metadata mechanism.
Some alignment with OGC API - Records have been integrated and the best practices have evolved further.
It is accompanied by various minor changes and clarifications.

This is a beta-release with the option to make changes before a final 1.1.0 release if the feedback of the STAC community asks for it in the next weeks. Currently, no further changes are planned at the time of this release though.

We'd appreciate if the STAC community takes some time to implement the new version and give feedback so that we can ensure the new version is mature and well-received by the community.

The following changes have been made to the specification since v1.0.0:

Added

• bands is a new field in common metadata to replace eo:bands and raster:bands (#1213)
• The fields data_type, nodata, statistics and unit have been added to common metadata (#1213)
• The keywords field known from Collections is available in common metadata. (#1187)
• New fields method, headers and body in the Link Object. (#1198)
• The license field additionally supports SPDX expressions and the value other.
• The roles field known from Assets and Providers is available in common metadata. (#1267)
• The collection relation type is added to the list of known relation types. (#1236)
• The item_assets field in Collections are integrated from extension into the core Collection spec. (#1275)
• Validation for absolute self link in item schema. (#1281)
• Best practice: Link titles should exactly reflect the title of the corresponding entity (#1168)

Changed

• Common Metadata:
  • Clarify in various field descriptions that the fields do not only apply to Items
  • Validate the fields also in Catalogs, Collections and Links
  • If a description is given, require that it is not empty
• Clarified URL resolving mechanics, e.g. that trailing slashes in URLs are significant (#1212)
• All JSON Schema $id values no longer have # at the end.
• Two spatial bounding boxes in a Collection don't make sense and will be reported as invalid by the schema. (#1243)
• Clarify in descriptions that start_datetime and end_datetime are inclusive bounds (#1280)
• Moved the STAC structural relations into commons
• Moved general descriptions about Assets and Links into commons
• Moved common metadata from the item-spec into commons, but kept the JSON schemas in the item-spec for backward compatibility

Deprecated

• license: The values proprietary and various are deprecated in favor of SPDX expressions and other.

Removed

• "Strongly recommended" language around self links in the item spec. (#1173)

Fixed

• Several typos and minor language changes
• Clarification on unique parent link requirement (#1279)
• Clarified that collection IDs should be unique across all collections in the corresponding root catalog
• Clarified that item IDs should be unique per collection
• Clarified which media types should be used for the hierarchical relation types
• Clarified in the Markdown specification that GeometryCollections are not allowed as Item Geometry (#1160)
• Best practice: Do not recommend subdirectories for Items without sidecar files (#1195)
• Clarified that multiple collections can point to an Item, but an Item can only point back to a single collection. (#1273)
• Restructured asset role types and clarified usage of the roles thumbnail, overview and visual (#1272)
• Clarified that JSON Schema draft-07 is the default version for Collection summaries and other versions may not be supported

Thanks Contributors @m-mohr @gadomski @emmanuelmathot @philvarner @sankichi92 @christophfriedrich @dwsilk @matthewhanson @cholmes @wilsaj @tschaub @jonhealy1 @nkleinbaer @jedsundwall @jbants

v1.0.0

Version 1.0.0 is the first completely stable release of the SpatioTemporal Asset Catalog specification!

The following listed changes are just the very minor tweaks between version 1.0.0-rc.4 and 1.0.0. The specification itself did not change at all, it was just minor tweaks in the supporting documents. For the full list of changes in the release candidate and beta releases leading up to 1.0.0 see the 1.0.0 changelog

[v1.0.0] - 2021-05-25

Added

• Updated best practices to add a recommendation to include title in links where possible. (#1133)

Changed

• Updated version numbers for 1.0.0 release.
• Final UML tweaks for latest changes. (#1134)
• Removed ItemCollection from the STAC detection heuristic in Best Practices. It can't easily be differentiated from GeoJSON FeatureCollections any longer. (API#141)

v1.0.0-rc.4

[v1.0.0-rc.4] - 2021-05-11

Changed

• An empty Catalog is now allowed, removed the requirement that it must have a child or item link. (#1115)
• An open date range to both sides is now allowed in the Collection's temporal extents. (#1125)
• Catalog and Collection JSON Schemas don't have a common JSON Schema any more. (#1122)

Removed

• Catalogs don't support summaries any more. (#1122)

Fixed

• Added clarification around when an extension should be included in stac_extensions. (#1123)
• JSON Schemas don't allow "shortcuts" for core extensions any longer. (#1121)
• Various examples fixes.

v1.0.0-rc.3

[v1.0.0-rc.3] - 2021-04-29

Added

• Summaries are allowed to specify JSON Schema in addition to ranges and sets of values. (#1045)
• Added preview relation type for interoperable thumbnails to best practices. (#1090)
• Recommendation to include both root and parent relation types when they point at the same file. (#1098)
• Overview section linking to various foundational standards. (#1111)

Changed

• The first extent in a Collection is always the overall extent, followed by more specific extents. (#1064, opengeospatial/ogcapi-features#520)
• Updated examples for automatic collection creation from code and validation (#1080)
• Clarified that stac_extensions should also list extensions that are used in Collection summaries. (#1077)
• The Stats Object for Summaries has been renamed to Range Object (no functional change). (#1093)
• changed, created (common metadata) and temporal extents (collections): Timestamps must be always in UTC (#1095)
• Clarified that collection summaries do not require that all property fields are summarized. (#1106)
• Clarified that gsd should only be used on an asset to represent the sensor, not just different processing. (#1105)
• Clarified that leaving a field out is not equivalent to setting it as null. (#1111)

v1.0.0-rc.2

[v1.0.0-rc.2] - 2021-03-31

Changed

• Required properties of type string require a minimum length of 1. (#1065)
• gsd must be greater than 0. (#1068)

Removed

• The remaining extensions in the spec (EO, Projection, Scientific Citation and View) have been moved out of the core specification, into their own repos in the stac-extensions GitHub organization. They must now be referred to by their schemas directly - the name shortcuts for them are no longer valid. The concept of the 'named shortcut' also goes away entirely. (#1070)

Fixed

• Collection Assets were specified as required (only in written text, not in JSON Schema), but that was incorrectly copied over from the former collection-assets extension. Collection Assets are not required.
• Clarified that the values in summaries (both for ranges and sets of values) must follow the data type of the property they summarize. (#1069)

v1.0.0-rc.1

[v1.0.0-rc.1] - 2021-03-03

Added

• Catalog and Collection now require a type parameter, to be set to Catalog or Collection for clients to more easily distinguish them easily. (#971)
• Collection specification adds Assets (previously needed Collections Asset extension to do that). (#1008)
• 'via' and 'canonical' rel types are now options in Items. (#884)
• In Extensions list there is now reference to three new (non-core) extensions: processing, file info and card4l. These would have been added to the stac-spec repo, except all non-core extensions were moved to stac-extensions org. (#1024)
• 'summaries' are now available in the Catalog spec, so both catalogs and collections can make use of it. (#903)
• There is a new recommendation to enable CORS. (#940)
• A Best Practice section on 'requester pays' cloud buckets was added. (#1021)
• A new Best Practice section explains Asset Roles, plus some lists of potential roles for people to use (in best practices, sar and eo). (#989)
• There is a new Best Practice recommendation to keep collections at consistent levels. (#1009)

Changed

• The Stats Object for Collection summaries changed min to minimum and max to maximum to align with JSON Schema. (#967)
• URIs (usually found int properties like href, url) are now validated using the iri-reference format in JSON Schema (allows international characters in URIs) (#953)
• Enhanced the way the spec talks about ID's to encourage more global uniqueness. (#883)
• Clarified how collection-level asset object properties do not remove the need for item-level asset object properties in the item-assets extension (#880)
• Made summaries to be strongly recommended - everyone should strive to implement them, as they are very useful. (#985)
• Moved examples from individual directories into a single /examples folder at the root, and evolved them to be more representative. (#955)
• Renamed "Scientific Extension" to "Scientific Citation Extension" (#990)
• Relaxed the regular expression for DOIs in the scientific extension (#910)
• proj:geometry allows all GeoJSON geometries instead of just a polygon. (#995)

Removed

• Checksum extension (field checksum:multihash). Use File Info extension (field file:checksum) instead for assets. There's no replacement for links. (#934)
• Collection Assets extension, as the core construct of Assets in a Collection is now part of the core Collection spec. No change is required except removing collection-assets from the list of stac_extensions. (#1008)
• Numerous extensions (Data Cube, Item Assets, Point Cloud, SAR, Single File STAC, Tiled Assets, Timestamps & Versioning) have been moved out of the core specification, into their own repos in the stac-extensions GitHub organization. They must now be referred to by their schemas directly - the name shortcuts for them are no longer valid. (#1024)

Fixed

• Fixed JSON Schema for providers (Collections and Items) to be an object and require a name. (#924)

v1.0.0-beta.2

[v1.0.0-beta.2] - 2020-07-08

Added

• JSON-schema file in the Point Cloud extension.

Changed

• Clarification on null geometries, making bbox not required if a null geometry is used.
• Multiple extents (bounding boxes / intervals) are allowed per Collection

Removed

• Validation instructions

Fixed

• Fixed several JSON Schemas
• Fixed examples

v1.0.0-beta.1

[v1.0.0-beta.1] - 2020-06-02

Removed

• The API portion of STAC has been split off into a new repository: stac-api-spec and will start being versioned and released separately than the core STAC spec.
• proj4 string from proj extension
• Various warnings about how the spec is very early and likely will change.
• implementations.md (migrated to https://stacspec.org) and how-to-help.md (migrated to https://github.com/stac-utils/stac-ecosystem).
• commons extension completely removed: Items should contain all properties and not default to a common set at the Collection level
• ItemCollection removed from stac-spec core repo, will migrate to stac-api-spec as that is the only place it is used.

Added

• 'alternate' as a listed 'rel' type with recommended 'text/html' to communicate there is an html version.
• Added a code of conduct based on github's template.
• Overview document that gives a more explanatory discussion of the various parts of the spec and how they relate
• Several new sections to 'best practices' document.
• Added the ability to define Item properties under Assets (item-spec/item-spec.md)
• Add proj:shape and proj:transform to the projections extension.
• Collection-level assets extension
• Instructions on how to run check-markdown locally
• Timestamps extensions (adds fields published, expires and unpublished)
• created and updated can be used in the assets to specify the creation / update times of the assets.
• Tiled Assets extension, for representing data that has been split into tiles

Changed

• Label extension types were clarified and types in README and JSON schema were brought into alignment
• Moved item recommendations to best practices, and added a bit more in item spec about 'search'
• Moved eo:gsd from eo extension to core gsd field in Item common metadata
• asset extension renamed to item-assets and renamed assets field in Collections to item_assets
• item-assets extension only requires any two fields to be available, not the two specific fields title and type
• datetime allows null as value, but requires start_datetime and end_datetime then
• Extensions sat, scientific and view: At least one field is required to be specified.
• Single File STAC extension changed to be a complete STAC catalog + GeoJSON FeatureCollection that contains collections and items.
• Improved several JSON Schemas

Fixed

• Datacube extension: cube:dimensions was not flagged as required.

v0.9.0

v0.9.0 - 2020-02-26

Added

• ItemCollection requires stac_version field, stac_extensions has also been added
• A description field has been added to Item assets (also Asset definitions extension)
• Field mission to Common Metadata fields
• Extensions:
  • Version Indicators extension, new version and deprecated fields in STAC Items and Collections
  • Data Cube extension can be used in Collections, added new field description
  • Asset Extension: new description and roles fields
  • New Projection Extension to describe Items with Assets that have an associated geospatial projection
  • New View Geometry Extension
• STAC API:
  • Added the Item and Collection API Version extension to support versioning in the API specification
  • Run npm run serve or npm run serve-ext to quickly render development versions of the OpenAPI spec in the browser
• Basics added to Common Metadata definitions with new description field for
  Item properties
• New fields to the link object to facilitate pagination support for POST requests
• data role, as a suggestion for a common role for data files to be used in case data providers don't come up with their own names and semantics
• Clarification text on HTTP verbs in STAC API

Changed

• Support for CommonMark 0.29 instead of CommonMark 0.28
• Collection field property and the merge ability moved to a new extension 'Commons'
• Added attribute roles to Item assets (also Asset definitions extension), to be used similarly to Link rel
• Updated API yaml to clarify bbox filter should be implemented without brackets. Example: bbox=160.6,-55.95,-170,-25.89
• Collection summaries merge array fields now
• Several fields have been moved from extensions or item fields to the Common Metadata fields:
  • eo:platform / sar:platform => platform
  • eo:instrument / sar:instrument => instruments, also changed from string to array of strings
  • eo:constellation / sar:constellation => constellation
  • dtr:start_datetime => start_datetime
  • dtr:end_datetime => end_datetime
• Moved angle definitions from extensions eo and new view extension
  • eo:off_nadir -> view:off_nadir
  • eo:azimuth -> view:azimuth
  • eo:incidence_angle -> view:incidence_angle
  • eo:sun_azimuth -> view:sun_azimuth
  • eo:sun_elevation -> view:sun_elevation
• Extensions:
  • Data Cube extension: Changed allowed formats (removed PROJ string, added PROJJSON / WKT2) for reference systems
  • Checksum extension is now using self-identifiable hashes (Multihash)
  • Changed sar:type to sar:product_type and sar:polarization to sar:polarizations in the SAR extension
• STAC API:
  • The endpoint /stac has been merged with /
  • The endpoint /stac/search is now called /search
  • Sort Extension - added non-JSON query/form parameter format
  • Fields extension has a simplified format for GET parameters
  • search extension renamed to context extension. JSON object renamed from search:metadata to context
  • Removed "next" from the search metadata and query parameter, added POST body and headers to the links for paging support
  • Query Extension - type restrictions on query predicates are more accurate, which may require additional implementation support
• Item title definition moved from core Item fields to Common Metadata Basics
  fields. No change is required for STAC Items.
• putFeature can return a PreconditionFailed to provide more explicit information when the resource has changed in the server
• Sort extension now uses "+" and "-" prefixes for GET requests to denote sort order.
• Clarified how /search links must be added to / and changed that links to both GET and POST must be provided now that the method can be specified in links

Removed

• version field in STAC Collections. Use Version Extension instead
• summaries field from Catalogs. Use Collections instead
• Asset Types (pre-defined values for the keys of individual assets, not media types) in Items. Use the asset's roles instead
• license field doesn't allow SPDX expressions any longer. Use various and links instead
• Extensions:
  • eo:platform, eo:instrument, eo:constellation from EO extension, and sar:platform, sar:instrument, sar:constellation from the SAR extension
  • Removed from EO extension field eo:epsg in favor of proj:epsg
  • gsd and accuracy from eo:bands in the EO extension
  • sar:absolute_orbit and sar:center_wavelength fields from the SAR extension
  • data_type and unit from the sar:bands object in the SAR extension
  • Datetime Range (dtr) extension. Use the Common Metadata fields instead
• STAC API:
  • next from the search metadata and query parameter
• In API, removed any mention of using media type multipart/form-data and x-www-form-urlencoded

Fixed

• The license field in Item and Collection spec explicitly mentions that the value proprietary without a link means that the data is private
• Clarified how to fill stac_extensions
• More clarifications; typos fixed
• Fixed Item JSON Schema now allOf optional Common Metadata properties are evaluated
• Clarified usage of optional Common Metadata fields for STAC Items
• Clarified usage of paging options, especially in relation to what OGC API - Features offers
• Allow Commonmark in asset description, as it's allowed everywhere else
• Put asset description in the API
• Fixed API spec regarding license expressions
• Added missing schema in the API Version extension
• Fixed links in the Landsat example in the collection-spec