LookNorth Data Standard
Purpose of this document#
This document has been written and will be maintained as a reference for required formats in the productization of data and delivery of content via the web.
Philosophy#
By establishing standards in the formatting and presentation of data across LookNorth we can improve platform quality while promoting component reuse and reducing development time.
STAC#
Spatial Temporal Asset Catalogs are a common format to represent geospatial information. LookNorth Hosts a [Centralized Catalog] where data products are curated. By useing a common data calaloging format, software can be developed in a way that it can work interoperable accross datasets and applications.
Collections#
Collections in STAC are meant to provide a collection of geospatial products. In Practice, Collections are used a location to store the results of a service along with any service level attribution that are common to all products within the service
Format#
Attributes#
Items#
The core element of STAC is the Item. An item is a singular representation of an spatial temporal asset. It is a json object with a series of properties, links and assets that contain information about and locations of all data products.
Format#
The specification can be found Here.
LookNorth applications use the information found in the properties to aid in the display of data products and aid in the orgainization and filtering in data.
The bbox and geometry fields are also using in the display and spatial filtering of data.
Attributes#
from STAC Item Spec
This object describes a STAC Item. The fields id, type, bbox, geometry and properties are
inherited from GeoJSON.
| Field Name | Type | Description |
|---|---|---|
| stac_version | string | REQUIRED. The STAC version the Item implements. |
| stac_extensions | [string] | A list of extensions the Item implements. |
| id | string | REQUIRED. Provider identifier. As most geospatial assets are already defined by some identification scheme by the data provider it is recommended to simply use that ID. Data providers are advised to include sufficient information to make their IDs globally unique, including things like unique satellite IDs. |
| type | string | REQUIRED. Type of the GeoJSON Object. MUST be set to Feature. |
| geometry | GeoJSON Geometry Object | REQUIRED. Defines the full footprint of the asset represented by this item, formatted according to RFC 7946, section 3.1. The footprint should be the default GeoJSON geometry, though additional geometries can be included. Coordinates are specified in Longitude/Latitude or Longitude/Latitude/Elevation based on WGS 84. |
| bbox | [number] | REQUIRED. Bounding Box of the asset represented by this item using either 2D or 3D geometries. The length of the array must be 2*n where n is the number of dimensions. The array contains all axes of the southwesterly most extent followed by all axes of the northeasterly most extent specified in Longitude/Latitude or Longitude/Latitude/Elevation based on WGS 84. When using 3D geometries, the elevation of the southwesterly most extent is the minimum depth/height in meters and the elevation of the northeasterly most extent is the maximum. This field enables more naive clients to easily index and search geospatially. STAC compliant APIs are required to compute intersection operations with the item's geometry field, not its bbox. |
| properties | Properties Object | REQUIRED. A dictionary of additional metadata for the item. |
| links | [Link Object] | REQUIRED. List of link objects to resources and related URLs. A link with the rel set to self is strongly recommended. |
| assets | Map<string, Asset Object> | REQUIRED. Dictionary of asset objects that can be downloaded, each with a unique key. Some pre-defined keys are listed in the chapter 'Asset types'. |
| collection | string | The id of the STAC Collection this Item references to (see collection relation type). This field is required if such a relation type is present. This field provides an easy way for a user to search for any Items that belong in a specified Collection. |
LookNorth makes use of extensions in its asset catalogs. This provides a way for datasets to select subsets of attribution contexually
Assets#
Format#
Attributes#
Date Time Strings. ISO 8601
Vector Assets#
Vector assets must be linked to a url which returns a well formed geojson object will be returned.
Raster Assets#
Raster attributes indended for display must be prepared and hosted as 8bit rgb Cloud Optimized Geotifs.