Element Description
The Spatial Extent element describes the geographic extent or coverage of data provided in a file or in a data collection.
Best Practices
In the CMR, the spatial extent of data may be specified as a horizontal spatial domain, a vertical spatial domain, or an orbital spatial domain. The type of spatial domain being described in the metadata is identified via the 'Spatial Coverage Type' metadata element. There are five different controlled vocabulary options for 'Spatial Coverage Type' in UMM-Common. These include:
- Horizontal
- Vertical
- Orbital
- Horizontal and Vertical
- Orbital and Vertical
Each spatial domain requires different information. These are summarized below:
Horizontal
Horizontal spatial extent refers to the flat surface of the Earth covered by data. For horizontal spatial extent, coverage must be specified as either Cartesian or Geodetic via the Coordinate System element:
SpatialExtent/HorizontalSpatialDomain/Geometry/CoordinateSystem:
Choice of:
- CARTESIAN
- GEODETIC
Please see the Coordinate Systems section of the CMR Data Partner User Guide for instructions on how to assign the appropriate coordinate system.
Furthermore, there are four different options for expressing horizontal spatial coverage. Only one of these options may be selected, however, the selected option may be repeated as many times as necessary (e.g. you can't provide a bounding rectangle and a point, but you can provide multiple bounding rectangles). The four options are:
(1) Point
- A point location defined by a latitude and longitude coordinate. Multiple points may be provided if necessary.
(2) Bounding Rectangle
- A rectangle defined by a north latitude coordinate, south latitude coordinate, east longitude coordinate, and west longitude coordinate. The north bounding latitude may not exceed 90 degrees, the south bounding coordinate may not be less that -90 degrees, the west bounding coordinate may not be smaller than -180 degrees, and the east bounding coordinate may not exceed 180 degrees.
(3) GPolygon
- A polygon defined by latitude/ longitude point pairs. The more points are provided, the more detailed the polygon will be. Exclusion zones within the polygon can also be identified. Please see the CMR Data Partner User Guide for more details.
(4) Line
- A width-less line defined by latitude/ longitude point pairs. Multiple points may be provided to express a complex line. Please see the CMR Data Partner User Guide for more details.
Vertical
Vertical spatial domain can be used to describe coverage of data with a vertical component. The type of vertical coverage being described in the metadata is identified via the 'Vertical Spatial Domain/ Type' metadata element. There are five different controlled vocabulary options for 'Vertical Spatial Domain/ Type' in UMM-Common. These include:
SpatialExtent/VerticalSpatialDomain/Type:
Choice of:
- Atmosphere Layer
- Maximum Altitude
- Minimum Altitude
- Maximum Depth
- Minimum Depth
Once a Type is selected, an accompanying value in the SpatialExtent/VerticalSpatialDomain/Value field must also be provided. For example, if "Maximum Altitude" was selected as the Type, the corresponding Value could be "50 KM".
Orbital
When data is collected via satellite, the Orbit Parameters metadata elements may be used to describe spatial coverage. Please see the CMR Data Partner User Guide for additional details on how Orbit Parameters are used by the backtrack search algorithm for conducting spatial searches. Orbit Parameters includes the following sub-elements:
Swath Width: The width of the strip of the Earth's surface from which geospatial data are collected by a satellite, in kilometers. Just provide the number, the unit of kilometers is implied. If providing orbit parameters, Swath Width is required.
Period: The time it takes a satellite to complete one complete orbit around the Earth, in decimal minutes. Just provide the number, the unit of decimal minutes is implied. If providing orbit parameters, Period is required.
Inclination Angle: The angle between the equatorial plane of the Earth and the orbital plane of a satellite, in degrees. Just provide the number, the unit of degrees is implied. If providing orbit parameters, Inclination Angle is required.
Number of Orbits: "Indicates the number of orbits."
Start Circular Latitude: "The latitude start of the orbit relative to the equator. This is used by the backtrack search algorithm to treat the orbit as if it starts from the specified latitude. This is optional and will default to 0 if not specified."
Furthermore, the Granule Spatial Representation element is a required element. This element identifies how spatial extent is expressed in the granule metadata associated with a collection. The spatial representation used in the collection metadata can be different than what is used in the granule metadata. Granule Spatial Representation is a controlled vocabulary field in the UMM-Common schema with the following options:
- CARTESIAN
- GEODETIC
- ORBIT
- NO_SPATIAL
The granule spatial representation selected at the collection level must be utilized by the granules. Please see the Collection & Granule Spatial Relationships section of the CMR Data Partner User Guide for additional details.
The spatial extent of the granules should always fall within the spatial extent specified in the collection level metadata (and vice versa). It is the responsibility of the metadata author to ensure that collection-granule spatial relationships are compatible.
Examples:
Element Specification
Model | Element | Type | Usable Valid Values | Required? | Cardinality |
---|---|---|---|---|---|
UMM-C | CollectionProgress | Enumeration | PLANNED ACTIVE COMPLETE NOT APPLICABLE | Yes | 1 |
Value needed for translations:
The following value is needed by the CMR to translate older non UMM compliant records to and from the UMM and other supported specifications where non required elements are considered required but no valid is given. This is needed partly because the CMR still allows a non UMM compliant record to be ingested with warnings.
NOT PROVIDED - It is necessary for this value to exist so that the CMR can translate older non UMM compliant records into the latest UMM specification where CollectionProgress is required. This value should not be used by metadata providers.
Metadata Validation and QA/QC
All metadata entering the CMR goes through the below process to ensure metadata quality requirements are met. All records undergo CMR validation before entering the system. The process of QA/QC is slightly different for NASA and non-NASA data providers. Non-NASA providers include interagency and international data providers and are referred to as the International Directory Network (IDN).
Please see the expandable sections below for flowchart details.
Dialect Mappings
UMM Migration
UMM Version 1.9.0 | Translation Direction | UMM Version 1.10.0 |
---|---|---|
PLANNED | ↔ | PLANNED |
IN WORK | ↔ | ACTIVE |
COMPLETE | ↔ | COMPLETE |
NOT APPLICABLE | ↔ | NOT APPLICABLE |
NOT PROVIDED | ↔ | NOT PROVIDED |
Any other value | → | NOT PROVIDED |
Future Mappings
History
UMM Versioning
Version | Date | What Changed |
---|---|---|
1.10.0 | Changes would be tracked here | |
1.9.0 |
ARC Documentation
Version | Date | What Changed | Author |
---|---|---|---|
1.0 | 2/19/18 | Recommendations/priority matrix transferred from internal ARC documentation to wiki space |