Interim Collection Comparison Report for Big Earth Data Initiative

Metadata Source: NASA Common Metadata Repository

Metadata Dialect: ISO 19115-2

Evaluation Target: Spatial Extent Elements

John Kozimor – The HDF Group 

The ESDIS Common Metadata Repository (CMR) recognizes the importance of documenting the spatial extent of the resource described by the metadata. Spatial Extent fields are represented by the Spatial Extent concept in the UMM-Common metadata model.

The table below shows the distribution of Spatial Extent fields represented in ISO 19115-2 for CMR metadata collections. This table provides a comparison of the fields utilized by NASA CMR metadata collections for describing spatial extent content.

We examined 2158 metadata records from 16 collections extracted from the CMR during October 2015. A value of 1 or more typically (although not necessarily) indicates that the element is included one or more times in each record in a collection. A value < 1.0 is typically the percentage of records in a collection that include the metadata element. Empty cells which indicate a value of 0 are shaded in pink.  Pink cells indicate the element is completely missing from the collection.

The analysis below shows that Bounding Extent (east,north,south,west) elements are populated to some extent for all the collections evaluated.  A few of the collections evaluated have a  completeness values of < then one, which indicates not all records in the collection include this field. Overall CMR metadata collection are doing a very consistent job of documenting the bounding extent fields.  The pink fields in the lower portion of the table highlight the use of GML point and polygon fields by NSICDV0 and ORNL_DAAC.

Table 1:  Distribution of Spatial Extent fields in CMR metadata collections

Collection Metadata Records - March 2016