STAC Metadata

All imagery data products are delivered with acquisition time, radiometric, geometric, and other various metadata properties delivered in a JavaScript Object Notation (JSON) format ASCII text file that aligns with the SpatioTemporal Asset Catalog (STAC) open geospatial standard. For more background information please visit the STAC specification website.

Catalog File Contents

The catalog file is a STAC catalog file for a catalog with a single item. The path to that item's STAC JSON file can be located in the list of links. The item has a 'rel' value of 'item' and can be used to locate the items STAC metadata description.

General Information

The following describes general information fields.

Field Name	Type	Description
type	string	Describes the type of item
stac_version	string	STAC version
id	string	STAC unique identifier
created	string	Creation datetime of this file as ISO 8601 formatted datetime, in UTC (YYYY-MM- DDTHH:MM:SSZ)
updated	string	Last update datetime of this file as ISO 8601 formatted datetime, in UTC (YYYY-MM- DDTHH:MM:SSZ)
stac_extensions	[string]	List of STAC extensions included in this file

Sensor Information

The following describes the type of sensor used to capture the images.

Field Name	Type	Description
sensor_mode	string	Operation mode of the sensor
sensor_type	string	Type of the sensor
product_type	string	Output product

License & Provider

The following describes the license and provider information.

Field Name	Type	Description
license	string	The type of license. Full license provided in links
providers	[Provider Object]	Information describing Wyvern as data provider
links	[Link Object]	List of resource link objects and related URLs
License Link Object
rel	string	Relationship between the current document and the linked document
href	string	The actual link in the format of an URL
title	string	Human-readable title
Providers Object
name	string	Name of the organization
roles	[string]	Roles of the provider
url	string	Homepage of the provider

Satellite Information

The following describes the satellite and constellation that captured the imagery.

Field Name	Type	Description
constellation	string	The name of the constellation
platform	string	The name of the satellite
instruments	[string]	Name of instrument used
sat:platform_international_designator	string	The International Designator

Capture Timestamps

The following describes the timestamps of the image capture.

Field Name	Type	Description
datetime	string	The mid-way time of the capture as ISO 8601 formatted datetime, in UTC (YYYY-MM- DDTHH:MM:SSSSSSZ)
start_datetime	string	The start time of the capture as ISO 8601 formatted datetime, in UTC (YYYY-MM- DDTHH:MM:SSSSSSZ)
end_datetime	string	The end time of the capture as ISO 8601 formatted datetime, in UTC (YYYY-MM- DDTHH:MM:SSSSSSZ)

Processing Information

The following describes information about the processing chain.

Field Name	Type	Description
processing:level	string	The processing level of the delivered data product
processing:facility	string	The name of the facility that produced the data
processing:version	string	The version of the primary processing software or processing chain that produced the data

View Geometry Information

The following describes the position of both the satellite and sun during imaging collection.

Field Name	Type	Description
view:off_nadir	number	The angle from the sensor between nadir (straight down) and the scene centre measured in degrees (0° to 20°)
view:incidence_angle	number	The incidence angle is the angle between the vertical (normal) to the intercepting surface and the line of sight back to the satellite at the scene centre measured in degrees (0° to 20°)
view:azimuth	number	Viewing azimuth angle. The angle measured from the sub-satellite point (point on the ground below the platform) between the scene centre and true north. Measured clockwise from north in degrees (0° to 360°)
view:sun_azimuth	number	Sun azimuth angle. From the scene centre point on the ground, this is the angle between truth north and the sun. Measured clockwise in degrees (0° to 360°)
view:sun_elevation	number	Sun elevation angle. The angle from the tangent of the scene centre point to the sun. Measured from the horizon in degrees (15° to 90°)

Projection and Geospatial Data

The following describes how to interpret any geospatial data in this file or in the associated Cloud-Optimized GeoTIFF file.

Field Name	Type	Description
gsd	number	Ground sample distance measured in metres (m)
geometry	GeoJSON Geometry Object of type Polygon	The footprint of the item
bbox	[number]	Image bounding box in product Coordinate Reference System [xmin, ymin, xmax, ymax]
proj:epsg	number	EPSG code
proj:shape	[integer]	Number of pixels in Y and X directions for the default grid

Electro-Optical Information

The following describes data that represents a snapshot of the Earth for assets.

Field Name	Type	Description
eo:cloud_cover	number	Estimate of cloud cover, in %
eo:bands	[Band Object]	An array of available bands where each object is a Band Object
Band Object
name	string	The name of the band, as "Band_<centre wavelength in nanometres>nm"
common_name	string	The name commonly used to refer to the band
centre_wavelength	number	Centre wavelength of the band in micrometres (μm)
full_width_half_max	number	The full width at half-maximum (FWHM) for this band in micrometres (μm)
solar_illumination	number	The solar illumination for each band which represents the ESUN solar irradiance generated using Thuillier 2003 dataset as measured at half the maximum transmission in units of 'W / (m2 * μm)'

Raster Information

The following describes the included raster assets.

Field Name	Type	Description
raster:bands	[Raster Band Object]	An array of available bands where each object is a [Band Object]
Raster Band Object
nodata	number	Pixel values used to identify pixels that are nodata in the band
sampling	string	Indicates whether a pixel value should be assumed to represent a sampling over the region of the pixel or a point sample at the centre of the pixel
data_type	string	The data type of the pixels in the band
unit	string	Unit denomination of the pixel value
scale	number	Multiplicator factor of the pixel value to transform into the value. Used for hyperspectral files only.
offset	number	Number to be added to the pixel value (after scaling) to transform into the value. Used for hyperspectral files only.
classification:classes	[Classification Class Object]	An array of available classes where each object is a [Class Object]
Class Object
value	integer	Value of the class
name	string	Short name of the class for machine readability
title	string	Human-readable name for use in, e.g. a map legend
description	string	Description of the class
nodata	boolean	If set to true classifies a value as a no-data value. Only present in the nodata class object

Wyvern-Specific Information

The following describes the information specific to Wyvern data.

Field Name	Type	Description
wyvern:radiometric_resolution	number	The radiometric resolution of the image, specified in bits

Asset File Information

The following describes the asset file information.

Field Name	Type	Description
href	string	URI to the asset object
type	string	Media type of the asset
title	string	The asset title
description	string	A description of the asset
file:checksum	string	File checksum
file:size	integer	The file size, specified in bytes
roles	[string]	The semantic roles of the asset