Disasters Charter Extension Specification

• Title: Disasters Charter
• Identifier: https://terradue.github.io/stac-extensions-disaster/v1.1.0/schema.json
• Field Name Prefix: disaster
• Scope: Item, Collection
• Extension Maturity Classification: Proposal
• Owner: @emmanuelmathot @fabricebrito

This document explains the Disasters Charter Extension to the SpatioTemporal Asset Catalog (STAC) specification.

The International Charter Space and Major Disasters is a non-binding charter which provides for the charitable and humanitarian acquisition and transmission of satellite data to relief organizations in the event of major disasters.

This extension provides with:

• Additional fields for common disaster properties such as type (e.g. cyclone, earthquake, flooding...).
• Additional fields for specific metadata for the charter such as the call or activation identifier.
• Best practises to describe several objects used in the Disasters Charter (Activation, Disaster Area, Acquisition...).

The extension is used in the Charter Processing Environment project to catalog all the objects.

• Examples:
  • Activation example: Shows the usage of the extension to describe an Activation. Item.
  • Acquisition example: Shows the usage of the extension to describe an Acquisition Item.
  • Call Collection example: Shows the usage of the extension to describe a Call Collection.
  • Area example: Shows the usage of the extension to describe an Area Item.
• JSON Schema
• Changelog

Glossary

This introductory section gives basic defintion of the terms used in the Disasters Charter and thus in this extension. More information about How the Charter works.

Activation

An Activation represents a Disaster event for which the Charter has been activated. An identifier is issued or recycled to be associated with a Call identifier. An Activation can be therefore linked to one or several Call(s).

Call

When an authorized User submits a request to mobilise the space and associated ground resources associated with the Charter members in order to obtain data and information on a major disaster, A new Call is issued. It is associated to a new or existing Activation. All related Acquisitions shall be associated to the Call, not directly the Activation.

Area

Regions that are affected by the disaster and identified by the parties involved in the Charter process.

Acquisition

Acquisition represents a satellite resource provided an Agency in the context of the Disaster. It can be an archived product or a planned acquisition. Each Acquisition records is associated to a Call.

Value Added Product

The Value Added Providers take the data provided by member agencies and interpret this, assessing what they see from the satellites and compiling it into Value Added Products.

Item Properties and Collection Fields

Fields

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

• Catalogs
• Collections
• Item Properties (incl. Summaries in Collections)
• Assets (for both Collections and Items, incl. Item Asset Definitions in Collections)
• Links

Field Name	Type	Description
disaster:class	string	REQUIRED. Identifier of the object described in the item or collection
disaster:call_ids	[int]	Identifiers of the related Call(s)
disaster:activation_id	int	Identifier of the related Activation
disaster:types	[string]	Disaster Types (one of the category)
disaster:country	string	Related Country identifier based on the ISO-3166 standard. In particular, the Alpha-3 representation. (e.g. BEL)
disaster:regions	[string]	Free text list identifying regions
disaster:activation_status	string	Activation status. One of open, closed, archived.
disaster:resolution_class	string	For Class acquisition, One of VLR, LR, MR, HR, VHR

Additional Field Information

disaster:types

The disaster:types is the commonly used category name to classify the type of disaster. Here is the list of accepted types:

Disaster Type	Description
cyclone	Tropical cyclones are weather phenomena which form over the Indian and south Pacific Oceans ocean through the release of energy generated by evaporation and saturation of water on the ocean's surface.
earthquake	Earthquakes occur following the release of energy when tectonic plates move apart. These plates move in currents in the Earth's lithosphere and the edges, which have been mapped to fault lines, sometimes collide.
fire	Wildfires occur when vegetated areas are set alight and are particularly common during hot and dry periods. They can occur in forests, grasslands, brush and deserts, and with sufficient wind can rapidly spread.
flood	Large Flooding occurs when bodies of water flow onto land that is normally dry.
ice	Ice on the surface of water or in compacted snow makes for treacherous conditions and can result in injuries if people slip and fall. Water sources may freeze, cutting off access for residents to clean water or heat.
snow_hazard	Snow Hazard occurs when temperatures drop below the freezing point, and there is sufficient water in clouds. Snow storms can quickly cause disruption to inhabited areas if the ground temperature is cold enough for the snow to settle.
tsunami	Tsunamis are seismic sea waves and typically occur as a result of underwater earthquakes or volcanic eruptions.
landslide	Landslides occur when ground on slopes becomes unstable. The unstable ground collapses and flows down the side of a hill or mountain, and can consist of earth, rocks, mud and any debris which may be caught in its wake.
storm_hurricane	Tropical cyclones are weather phenomena which form over the Atlantic and northeast Pacific Oceans through the release of energy generated by evaporation and saturation of water on the ocean's surface.
oil_spill	Oil spills occur when petroleum oil is released into the ocean following accidents, such as vessels crashing or damage and problems with oil platforms and drilling.
volcano	Volcanoes are points in the Earth's crust which have ruptured, allowing lava, ash, rocks and gas to erupt during periods of seismic activity.
explosive_event	Explosive Events are sudden and violent releases of energy, which can be caused by a number of factors, including human error, natural disasters, or deliberate acts.
other	In addition to the most common forms of natural disasters, there are other types of disasters which may benefit from satellite observations.

Important

Some previously applicable types have been deprecated and must be replaced by the new ones:

• flood_large and flash_flood are deprecated and must be replaced by flood.
• storm_hurricane_rural and storm_hurricane_urban are deprecated and must be replaced by storm_hurricane.

disaster:class

The disaster:class is the commonly used category name to classify the object described in the item or collection. Here is the list of suggested types:

• activation : Activation
• area : Area
• acquisition : Acquisition
• vap : Value Added Product

disaster:resolution_class

The disaster:resolution_class is category code to classify the resolution of the acquisition item.

• VLR : Very Low Resolution
• LR : Low Resolution
• MR : Medium Resolution
• HR : High Resolution
• VHR : Very High Resolution

This nomenclature is proper to the Disasters Charter and is used to classify the resolution of the satellite.

Other Extensions and Specifications

This extension uses and requires additional fields from other specifications or extensions.

The following specifications are relevant here:

• STAC Common Metadata
• STAC SAT Extension

Field Name	Type	Description
platform	string	Globally unique satellite identifier as defined in common metadata.
instruments	[string]	The instrument identifier as defined in common metadata.
datetime	string	REQUIRED. The disaster or acquisition time As defined in common metadata and STAC.
gsd	number	Ground sample distance as defined in common metadata.
sensor_type	string	The sensor type. One of optical or radar
eo:cloud_cover	number	Cloud cover as defined in the EO extension.

Additional REQUIRED fields according to the disaster:class:

Field Name	activation	area	acquisition	vap
platform			X	X (when applicable)
instruments			X	X (when applicable)
gsd			X	X (when applicable)
sensor_type			X	X (when applicable)
eo:cloud_cover			X (when applicable)	X (when applicable)

Relation types

The following types should be used as applicable rel types in the Link Object.

Type	Description
about	This link points to the disasterscharter.org page of the disaster
area	This link points to an area Item from an activation Item.
derived_from	This link should be used in all Value Added Product to identify one or more Acquisition(s) used to create it.

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