eodash STAC Extension Specification

• Title: eodash STAC extension
• Field Name Prefix: eodash, eox
• Scope: Collection, Item, Link, Asset
• Extension Maturity Classification: Proposal
• Owner: @eodash

This document explains the eodash STAC Extension to the SpatioTemporal Asset Catalog (STAC) specification The extension provides a set of properties to enrich STAC Collections and Items with metadata necessary for the eodash visualization client. These properties enable advanced, interactive features including:

• Dynamically generated user-interface forms for data processing.
• Client-side rendering of charts and data visualizations.
• Support for custom map projections.
• Application of custom color legends, and dynamic user-configurable styling.

For more extensions and concepts not covered by this extension specification and needed by eodash, refer to eodash STAC Documentation.

• Examples:
  • Item example: Shows the basic usage of the extension in a STAC Item
  • Collection example: Shows the basic usage of the extension in a STAC Collection
• JSON Schema
• Changelog

Fields

The fields below can be used in these parts of STAC documents:

• Catalogs
• Collections
• Items
• Assets
• Links

Collection Fields

These fields can be applied to the top-level of a STAC Collection object.

Field Name	Type	Description
eodash:mapProjection	Projection Object	Defines a custom map projection that the client can register and use for displaying data. This is essential for visualizing data in non-standard coordinate reference systems (e.g., polar stereographic).
eodash:jsonform	string	A URL pointing to a JSON Schema file. eodash uses this schema to dynamically generate a user interface form, allowing users to input parameters for data processing services.
eodash:vegadefinition	string	A URL pointing to a Vega or Vega-Lite JSON definition. eodash uses this to render charts from data returned by a service.
eox:colorlegend	Color Legend Object	Defines a custom color legend for client-side styling of rendered data

Item Fields

These fields can be applied at the top level of STAC Items.

Field Name	Type	Description
eodash:proj4_def	Projection Object	Defines a custom Proj4 projection for the item data.

Link Fields

These fields can be applied to STAC Links (in Collections, Items, or Catalogs).

Field Name	Type	Description
eodash:proj4_def	Projection Object	Defines a custom Proj4 projection for the linked resource. Commonly used in WMS links to specify the coordinate reference system.
eox:flatstyle	string | object	A URL pointing to a JSON object that extends OpenLayers Flat Styles, or the style object itself. Used for dynamic styling of web map links (WMS, WMTS, XYZ) and service links.

Asset Fields

These fields can be applied to STAC Assets (in Collections or Items).

Field Name	Type	Description
eodash:proj4_def	Projection Object	Defines a custom Proj4 projection for the asset data.
eox:flatstyle	string | object	A URL pointing to a style JSON object or the style object itself for dynamic asset styling.

Note: For data assets, styling is typically provided through links with rel: "style" rather than directly on the asset. The style link's href points to an OpenLayers Flat Style definition, and asset:keys specifies which assets the style applies to.

Projection Object

Both eodash:mapProjection and eodash:proj4_def use the same object structure:

Field Name	Type	Description
name	string	REQUIRED. A unique identifier for the projection (e.g., "EPSG:3031" or a custom name like "ORTHO:320500").
def	string	REQUIRED. The Proj4 definition string specifying the projection parameters.
extent	[number]	OPTIONAL. The valid coordinate bounds as [minX, minY, maxX, maxY] in the projection's units.

Color Legend Object

The eox:colorlegend property uses the following object structure:

Field Name	Type	Description
domain	[number]	REQUIRED. Array of numeric values defining the input domain for the color scale.
range	[string]	REQUIRED. Array of color values (hex codes, CSS colors) corresponding to the domain values.
scaleType	string	OPTIONAL. Type of scale to use. Valid values: "linear", "log", "pow", "sqrt", "symlog", "continuous", "discrete". Default is "linear".
title	string	OPTIONAL. Title text displayed with the color legend.
tickFormat	string	OPTIONAL. Format string for tick labels (e.g., ".0f" for integers, ".2f" for two decimal places).
width	number	OPTIONAL. Width of the color legend in pixels.
ticks	number	OPTIONAL. Approximate number of ticks to display on the legend.
tickValues	[number]	OPTIONAL. Explicit array of values where ticks should be placed, overriding automatic tick generation.
markType	string	OPTIONAL. Visual style of the legend marks. Implementation-specific values.

Related Extensions and Standards

This extension is designed to work with several other STAC extensions and standards:

• Projection Extension: For standard EPSG coordinate reference systems using proj:epsg
• Web Map Links Extension: For map service links (WMS, WMTS, XYZ) with additional properties like endpoint, method, and wmts:layer
• Render Extension: For visualization and styling metadata

For additional metadata properties used by eodash (such as locations, service configuration, and observation point handling), see the eodash STAC documentation.

Contributing

All contributions are subject to the STAC Specification Code of Conduct. For contributions, please follow the STAC specification contributing guide Instructions for running tests are copied here for convenience.

Running tests

The same checks that run as checks on PR's are part of the repository and can be run locally to verify that changes are valid. To run tests locally, you'll need npm, which is a standard part of any node.js installation.

First you'll need to install everything with npm once. Just navigate to the root of this repository and on your command line run:

npm install

Then to check markdown formatting and test the examples against the JSON schema, you can run:

npm test

This will spit out the same texts that you see online, and you can then go and fix your markdown or examples.

If the tests reveal formatting problems with the examples, you can fix them with:

npm run format-examples