Usability of the WIGOS standard for
Meteorological Satellite Observations
- Comparing WIGOS metadata to established OGC Standards on the
usage for Satellite Data -
Doc.No.
Issue
Date
:
:
:
EUM/ICT/TEM/16/872339
v1 Draft
29 August 2016
EUMETSAT
Eumetsat-Allee 1, D-64295 Darmstadt, Germany
Tel: +49 6151 807-7
Fax: +49 6151 807 555
http://www.eumetsat.int
© EUMETSAT
The copyright of this document is the property of EUMETSAT.
EUM/ICT/TEM/16/872339
v1 Draft, 29 August 2016
Usability of the WIGOS standard for Satellite observations
Table of Contents
REFERENCES ......................................................................................................................................... 3
1
INTRODUCTION .............................................................................................................................. 4
2
PURPOSE & SCOPE ....................................................................................................................... 4
3
EVALUATION OF THE USABILITY OF WIGOS METADATA FOR EO PRODUCTS ................... 4
3.1 General approach .................................................................................................................. 4
3.2 Mapping ISO19115(-2) to WIGOS metadata ......................................................................... 7
3.2.1 General ISO19115 mappings .......................................................................................... 7
3.2.1.1 MD_DataIdentification ................................................................................................ 7
3.2.1.2 MD_Distribution .......................................................................................................... 7
3.2.1.3 DQ_DataQuality ......................................................................................................... 7
3.2.2 EO related ISO19115-2 mappings ................................................................................... 7
3.2.2.1 Acquisition Information ............................................................................................... 8
3.2.2.1.1 MI_Platform: ......................................................................................................... 8
3.2.2.1.2 MI_Instrument: ..................................................................................................... 8
3.3 Mapping OGC O&M EOP to WIGOS ..................................................................................... 8
3.3.1 Mapping to OGC O&M EOP ............................................................................................ 8
3.3.2 Mapping OGC O&M EOP to WIGOS ............................................................................... 9
3.3.3 EarthObservation ............................................................................................................. 9
3.3.4 EarthObservationMetaData ............................................................................................. 9
3.3.4.1 General EO Metadata ................................................................................................ 9
3.3.4.2 Type ProcessingInformation..................................................................................... 10
3.3.4.3 Quality Information ................................................................................................... 11
3.3.5 EarthObservationEquipment .......................................................................................... 11
3.3.5.1 Acquisition ................................................................................................................ 11
3.3.5.2 Platform .................................................................................................................... 11
3.3.5.3 Instrument / Sensor .................................................................................................. 12
3.3.6 Footprint (FeatureOfInterest) ......................................................................................... 12
3.3.7 EarthObservationResult ................................................................................................. 13
4
RESULT SUMMARY...................................................................................................................... 13
List of Figures
Figure 1: General UML model of EO Collection and EO Product Metadata in OGC/HMA ..................... 5
Figure 2: Most important data types of OGC 10-157r4 ............................................................................ 6
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REFERENCES
[1]: WIGOS METADATA STANDARD. World Meteorological Organization Cg-17/Doc. 4.2.2(3),
ADD. 1. WORLD METEOROLOGICAL CONGRESS. Submitted by: Chairperson, Committee A.
Date: 29.5.2015.
[2]: Earth Observation Metadata profile of Observations & Measurements. OGC 10-157r4,
Version 1.1. Open Geospatial Consortium. 2014
[3]: EUMETSAT Long Term Archive – Submission Information Package (SIP). EUMETSAT
document EUM/TSS/TEN/14/761451.
[4]:
ESA
TM-21
Heterogeneous
Missions
Accessibility.
http://www.esa.int/About_Us/ESA_Publications/ESA_TM21_Heterogeneous_Missions_Accessibility
[5] ISO 19115:2003, Geographic information – Metadata (with ISO 19115:2003/Cor.1:2006,
Geographic information – Metadata – Technical Corrigendum 1)
[6] ISO-DIS 19115-2, Geographic information – Metadata – Part 2: Extensions for imagery
and gridded data, 2009
[7] ISO/TS 19139, Geographic information – Metadata – XML schema implementation, 2007.
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1
INTRODUCTION
An important aspect of the WIGOS (WMO Integrated Global Observing System)
implementation is ensuring maximum usefulness of WIGOS observations. Observations
without metadata are of very limited use: it is only when accompanied by adequate
metadata (data describing the data) that the full potential of the observations can be
utilized.
WIGOS observations consist of an exceedingly wide range of data from the manual
observations to complex satellite based observations. A comprehensive metadata standard
to cover all types of observations is by nature complex to define.
Therefore, the usability of the current WIGOS Metadata Standard [1] for the different types
of observations must be proofed.
2
PURPOSE & SCOPE
This document describes the results of a proof how far the WIGOS standard (only an
abstract model) [1] can already be used (or not) to describe data observed by
meteorological satellite.
In an earlier step this was started by mapping the WIGOS abstract model [1] to the
metadata model of the new Submission Information Package (SIP) (for describing EO
Products being delivered into the Archive) used by EUMETSAT [3]. This SIP model is aligned
with the HMA Earth Observation Metadata profile of Observations & Measurements [2].
Lots of the WIGOS elements are not relevant for EO but much more related to in-situ
sensors. On the other hand, some elements may be missing which are evident for describing
EO related datasets.
This document describes if (and which) important EO-related elements are not yet covered
by WIGOS Metadata. It also includes information indicating what should be changed to
allow a correct description of satellite observations.
3
EVALUATION OF THE USABILITY OF WIGOS METADATA FOR EO
PRODUCTS
3.1
General approach
Data observed by meteorological satellites are Earth Observation (EO) data or “EO
products”.
In the OGC as well in ESA´s Heterogeneous Missions Access (HMA) project [4] EO
products are described with a two-step approach. For this it is assumed that EO collections
are defined as sets of EO products sharing a common specification or characteristics. For
example, an EO collection can be defined as series of EO products of the same satellite (e.g.
MSG) and the same sensor (detector, e.g. SEVIRI/optical) acquired at different times. As a
result of this, EO Collection Metadata is differentiated from EO Product Metadata (see Figure
1).
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Usability of the WIGOS standard for Satellite observations
class Domain Model
Satellite
EO Product Metadata
EO Product
Platform
+has
+belongs
orbitNumber :int
track :int
acquisitinStation :char
processingDate :char
status :char
cloudCover :int
.....
EO Metadata
0..1
+has 1..*
+has
Instrument
InstrumentMode
0..*
+includesDataFrom
+belongsTo
0..*
+
+
+has +
+
1 +
+
+
0..1
0..*
+provides
0..*
+includesDataFrom
0..*
+belongsTo
1
EO Collection
+provides
0..*
EO Collection Metadata
+
+
+has
+
1 +
+
+
+
abstract :char
accessConstraint [0..n] :char
disseminationType [0..n] :char
producer [1..n] :char
topicCategory [0..n] :char
useConstraint [0..n] :char
.....
+
+
+
+
instrument [1..n] :char
satellite [1..n] :char
spatialExtent :char
temporalExtent :char
+has 0..*
Detector
Figure 1: General UML model of EO Collection and EO Product Metadata in OGC/HMA
EO Collection Metadata are more focused on the general application area (usage scenarios),
the dissemination channels, access and use constraints and on the producer of the data etc.
Nevertheless, it also includes metadata that is equally applicable to EO Products like
information on the acquisition type (e.g. satellite and instrument) or on spatial and temporal
extents describing the covered area. This metadata shall be interpreted as common to all EO
Products of the same collection so that it must not be repeated within the metadata of every
single EO Product. The metadata model is based on ISO19115-2 [6].
In contrast to EO Collection metadata, EO Product metadata is more geared to technical
details of the acquisition, quality, processing, archiving etc of a concrete EO Product instance
(Product Data Unit - PDU). Therefore, the baseline in OGC and HMA for product metadata
is the OGC Document 10-157r4 [2] which defines a metadata standard for describing Earth
Observation (EO) product metadata. It is defined as a profile of Observations and
Measurements (ISO 19156). Although OGC Document 10-157r4 has been developed in the
context of these HMA projects, the content is generic to Earth Observation (EO) product.
The most important data types of the OGC 10-157r4 standard are shown in Figure 2.
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Usability of the WIGOS standard for Satellite observations
class EOP
«FeatureType»
EarthObserv ation
+
+
metaDataProperty: EarthObservationMetaData
version: CharacterString = 2.1.0
constraints
{phenomenonTime.oclIsKindOf(TM_Period)}
{procedure.oclIsKindOf(EarthObservationEquipment)}
{featureOfInterest.oclIsKindOf(Footprint)}
{result.oclIsKindOf(EarthObservationResult)}
{observedProperty = result.parameter.phenomenon}
acquisitionSubType: CodeList [0..1]
acquisitionType: AcquisitionTypeValue
archivedIn: ArchivingInformation [0..*]
composedOf: EarthObservation [0..*]
doi: CharacterString [0..1]
downlinkedTo: DownlinkInformation [0..*]
histograms: Histogram [0..*]
identifier: CharacterString
creationDate: DateTime [0..1]
modificationDate: DateTime [0..1]
imageQualityDegradation: Measure [0..1]
imageQualityDegradationQuotationMode: DegradationQuotationModeValue [0..1]
imageQualityDegradationTag: CodeList [0..*]
imageQualityReportURL: anyURI [0..1]
imageQualityStatus: ImageQualityStatusValue [0..1]
linkedWith: EarthObservation [0..*]
parentIdentifier: CharacterString [0..1]
processing: ProcessingInformation [0..*]
productGroupId: CharacterString [0..1]
productQualityDegradation: Measure [0..1]
productQualityDegradationQuotationMode: DegradationQuotationModeValue [0..1]
productQualityDegradationTag: CodeList [0..*]
productQualityReportURL: anyURI [0..1]
productQualityStatus: ProductQualityStatusValue [0..1]
productType: CharacterString [0..1]
status: StatusValue
statusDetail: CharacterString [0..1]
statusSubType: StatusSubTypeValueEnumeration [0..1]
subsetOf: EarthObservation [0..*]
vendorSpecific: SpecificInformation [0..*]
«DataType»
ProcessingInformation
+
+
+
+
+
+
+
+
+
+
+
«DataType»
Archiv ingInformation
auxiliaryDataSetFileName: CharacterString [0..*]
compositeType: TM_PeriodDuration [0..1]
method: CharacterString [0..1]
methodVersion: CharacterString [0..1]
nativeProductFormat: CharacterString [0..1]
processingCenter: CodeList [0..1]
processingDate: DateTime [0..1]
processingLevel: ProcessingLevelValue [0..1]
processorName: CharacterString [0..1]
processingMode: CodeList [0..1]
processorVersion: CharacterString [0..1]
«CodeList»
SpectralRangeValue
+
+
+
+
+
INFRARED
NEAR-INFRARED
UV
VISIBLE
OTHER
+
+
+
centerOf: GM_Point [0..1]
multiExtentOf: GM_MultiSurface
orientation: PolygonOrientationValue [0..1] = CCW
+
+
+
+
+
browse: BrowseInformation [0..*]
product: ProductInformation [0..*]
mask: MaskInformation [0..*]
parameter: ParameterInformation [0..1]
coverage: CV_Coverage [0..*]
+
+
+
+
«DataType»
SpecificInformation
+
+
+
+
+
+
fileName: ServiceReference
referenceSystemIdentifier: ScopedName
subType: CodeList [0..1]
type: BrowseTypeValue
«DataType»
Dow nlinkInformation
+
+
acquisitionDate: DateTime [0..1]
acquisitionStation: CodeList
«DataType»
Instrument
+
+
+
acquisitionParameters: Acquisition [0..1]
instrument: Instrument [0..1]
platform: Platform [0..1]
sensor: Sensor [0..1]
localAttribute: CharacterString
localValue: CharacterString
+
+
+
+
+
+
+
+
+
ASCENDING
DESCENDING
orbitType: OrbitTypeValue [0..1]
serialIdentifier: CharacterString [0..1]
shortName: CharacterString
«DataType»
Sensor
+
+
+
+
+
ALTIMETRIC
ATMOSPHERIC
OPTICAL
RADAR
LIMB
«enumeration»
DegradationQuotationModeValue
operationalMode: CodeList [0..1]
resolution: Measure [0..1]
sensorType: SensorTypeValue [0..1]
swathIdentifier: CodeList [0..1]
wavelengthInformation: WavelengthInformation [0..*]
discreteWavelengths: MeasureList [0..1]
endWavelength: Measure [0..1]
spectralRange: SpectralRangeValue [0..1]
startWavelength: Measure [0..1]
wavelengthResolution: Measure [0..1]
+
+
+
+
+
+
+
Attributes
AUTOMATIC
MANUAL
+
+
+
CLOUD
SNOW
QUALITY
«CodeList»
Brow seTypeValue
+
+
+
QUICKLOOK
THUMBNAIL
ALBUM
«Enumerati...
OrbitTypeValue
LEO
GEO
«Enumeration»
AcquisitionTypeValue
fileName: ServiceReference
format: FormatValue
referenceSystemIdentifier: ScopedName [0..1]
type: MaskTypeValue
subType: CharacterString [0..1]
multiExtentOf: GM_MultiSurface
«CodeList»
SensorTypeValue
RASTER
VECTOR
«CodeList»
MaskTypeValue
ascendingNodeDate: DateTime [0..1]
ascendingNodeLongitude: Measure [0..1]
completionTimeFromAscendingNode: Measure [0..1]
lastOrbitNumber: Integer [0..1]
orbitDirection: OrbitDirectionValue [0..1]
orbitDuration: Measure [0..1]
orbitNumber: Integer [0..1]
startTimeFromAscendingNode: Measure [0..1]
wrsLatitudeGrid: ScopedName [0..1]
wrsLongitudeGrid: ScopedName [0..1]
illuminationAzimuthAngle: Angle [0..1]
illuminationZenithAngle: Angle [0..1]
illuminationElevationAngle: Angle [0..1]
instrumentAzimuthAngle: Angle [0..1]
instrumentZenithAngle: Angle [0..1]
instrumentElevationAngle: Angle [0..1]
incidenceAngle: Angle [0..1]
acrossTrackIncidenceAngle: Angle [0..1]
alongTrackIncidenceAngle: Angle [0..1]
pitch: Angle [0..1]
roll: Angle [0..1]
yaw: Angle [0..1]
«DataType»
Platform
«Enumeration»
OrbitDirectionValue
+
+
«DataType»
MaskInformation
fileName: ServiceReference
referenceSystemIdentifier: ScopedName [0..1]
size: MeasureList [0..1]
version: CharacterString [0..1]
timeliness: CodeList [0..1]
«DataType»
Wav elengthInformation
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
shortName: CharacterString [0..1]
description: CharacterString [0..1]
instrumentType: CharacterString [0..1]
«DataType»
ProductInformation
+
+
+
+
+
«CodeList»
FormatValue
«DataType»
Acquisition
«DataType»
Brow seInformation
archivingCenter: CodeList
archivingDate: DateTime
archivingIdentifier: Code [0..1]
«Enumeration»
PolygonOrientationValue
CW
CCW
OTHER
+
+
+
«FeatureType»
EarthObserv ationResult
«DataType»
EarthObserv ationMetaData
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
«FeatureType»
EarthObserv ationEquipment
«FeatureType»
Footprint
CALIBRATION
NOMINAL
OTHER
«CodeList»
StatusValue
+
+
+
+
+
+
+
+
ACQUIRED
ARCHIVED
CANCELLED
FAILED
PLANNED
POTENTIAL
QUALITYDEGRADED
REJECTED
«CodeList»
ProcessingLev elValue
+
+
+
+
1A
1B
2
3
«DataType»
Histogram
+
+
+
+
+
bandId: CharacterString [0..1]
max: Integer
mean: Decimal [0..1]
min: Integer
stdDeviation: Decimal [0..1]
Figure 2: Most important data types of OGC 10-157r4
Compared to CGMS-WMO Satellite Product Essential Information for WIS Discovery
Metadata (CGMS Metadata) and WIGOS Metadata the collection metadata used in
OGC/HMA relates more to the CGMS Metadata and the product metadata to WIGOS
metadata.
The main differences are minimally:

CGMS Metadata is implemented by the WMO-Core profile [???] of ISO19115 [5] /
ISO19139 [7] (and not ISO19115-2 [6]) accompanied by a document which guides an
editor how to integrate EO specific information (e.g. related to satellite,
instrument,…) by just using the means available with ISO19115/ISO19139 (e.g. using
specific vocabularies for keywords or specify types of links to descriptions…).

With WIGOS metadata it is NOT intended to describe single EO products (PDU´s)
but to provide additional EO related metadata for whole collections of EO products.

………..
In the following we´ll assume that the available OGC/HMA metadata models are very good
sets of metadata elements to describe EO data. Therefore, for an evaluation of the usability of
WIGOS metadata for the description of EO products (which are in reality EO collections as
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we have learned before) we need to take into account these two specifications. Concretely we
will prove the usability of WIGOS by mapping the most important OGC/HMA metadata
model elements to WIGOS metadata to check if WIGOS already sufficiently covers those.
3.2
Mapping ISO19115(-2) to WIGOS metadata
Here we need to check if important metadata elements to describe EO data which are just
defined in ISO19115(-2) (and not repeated in OGC 10-157r4) are covered with WIGOS
metadata.
3.2.1 General ISO19115 mappings
Here we need to check if important metadata elements to describe EO data which are already
defined in ISO19115 are covered by WIGOS metadata elements.
3.2.1.1 MD_DataIdentification

title: 2-01 (2-02)

creationDate/publicationDate/modificationDate: 1-03 (begin) ?

identifier: a unique URI would be good to have ….

(creator /) owner: 10-01/ 9-01

Abstract: 2-01 (2-02) ?

status (operational,…): 3-09

keywords: 2-01 (2-02) ?

resourceConstraints: 9-02

spatialExtent / geographicElement: 1-04


temporalExtent: 1-03
…
3.2.1.2 MD_Distribution

distributor: -

distributionFormat: -

distributionOrderProcess: -

digitalTransferOptions: -
3.2.1.3 DQ_DataQuality

Lineage: -
3.2.2 EO related ISO19115-2 mappings
Here we need to check if important metadata elements to describe EO data which are already
defined in ISO19115-2 are covered with WIGOS metadata.
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3.2.2.1 Acquisition Information
3.2.2.1.1 MI_Platform:

Identifier: s. 3.3.5.2

description: s. 3.3.5.2

citation: -
3.2.2.1.2 MI_Instrument:

identifier: s. 3.3.5.3


type: s. 3.3.5.3
description: s. 3.3.5.3

citation: -
3.3
Mapping OGC O&M EOP to WIGOS
3.3.1 Mapping to OGC O&M EOP
In an earlier step we started proving the applicability of WIGOS Metadata for data observed
by satellites by mapping the WIGOS abstract model to the metadata model of the new
Submission Information Package (SIP) (for describing EO Products being delivered into the
Archive) used by EUMETSAT. This SIP model is aligned with the HMA Earth Observation
Metadata profile of Observations & Measurements (EOP O&M) [2].
The
mapping
table
can
be
found
in
GoogleDocs:
https://docs.google.com/spreadsheets/d/1zcPAmQYJ_WrCk6-ZPgPG62775RIshQMcEbaIHYPUCY/edit#gid=127171090
In the following those columns of the mapping table are described which provide the
mapping to HMA O&M EOP:

Namespace: To which HMA O&M EOP Package is it mapped

Item Name: To which attribute of the assigned HMA O&M EOP package (or
something else e.g. in ISO19115) is it mapped

Description/Remarks:
Details on the HMA O&M EOP attribute (or something
else e.g. in ISO19115) where it is mapped to or alternatively additional information if
a mapping could not be found

Cardinality: Cardinality of the HMA O&M EOP attribute (or something else e.g. in
ISO19115) where it is mapped to

XPath:

Questions: Questions for EUMETSAT

Example: XML Example (if available)
XPath of the HMA O&M EOP attribute (if applicable) where it is mapped to
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The row colours in the mapping part to HMA O&M EOP have the following meaning:

dark green:
mapped to HMA O&M EOP

light green:
mapped to HMA O&M EOP, uncertain

light violet:
not mappable to HMA O&M EOP but (possibly) more related to
ISO19115(

light gray:
- 2) (collection metadata)
more related to HMA O&M EOP (than to collection) but not yet
considered in HMA O&M EOP

rose:
not related to EO

light yellow:
no final decision, uncertain
3.3.2 Mapping OGC O&M EOP to WIGOS
For the current elaboration it is more important to (vice versa) see if (minimally) the most
important metadata elements of HMA Earth Observation Metadata profile of Observations &
Measurements (EOP O&M) [2] can be mapped to WIGOS metadata.
At this point it shall be repeated that it is not the target to describe single data packages
of EO data but series of EO data (which are called collections in HMA) with the required
EO related elements. From this follows that EO product specific metadata elements will not
be considered.
For this purpose, in the following evaluations will be given for groupings of EO metadata
elements (aligned with the groupings found in a OGC 10-157r4 [2]).
In the future a table should be added (or referenced) here which includes the detailed
mapping of important OGC 10-157 metadata elements to WIGOS metadata elements.
3.3.3 EarthObservation

observedProperty: 1-01 (Observed variable – measurand)

resultTime – phenomenonTime: 7-13 (latency) of reporting

phenomenonTime (gml:timePeriod): 1-03 (Temporal extent)
3.3.4 EarthObservationMetaData
3.3.4.1 General EO Metadata
Some elements related to general EO metadata is sufficiently mapped, including (not
limited to):
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
acquisitionSubType: 5-04

downLinkedTo
o acquisitionStation: 3-07
o acquisitionDate: not needed because related to PDU
archivedIn
o archivingCenter: 9-01
o the other elements not needed because related to PDU


productType: describes the product type in case that mixed types are available within
a single collection, this is a ground segment specific definition: maybe not relevant

status: Values : - ARCHIVED - ACQUIRED - CANCELLED - FAILED
- PLANNED -
POTENTIAL - REJECTED : maybe only use the more general values like “ARCHIVED”: 3-09
Other elements related to general EO metadata is NOT sufficiently mapped:

DOI

statusSubtype: Refines the status of a product when the “status” is set to “ARCHIVED”.
Possible values:- “ON-LINE”- “OFF-LINE”
Especially linking to related information seems to be missing:


parentIdentifier: in O&M EOP used to link to the collection identifier. Could be
interesting in WIGOS to link e.g. to more general information (e.g. CGMS/WMOCore metadata)
subsetOf: in O&M EOP used to link to the “father” EO product (e.g. a phr:Scene is a
subset of a phr:DataStrip)

composedOf: in O&M EOP used to link to an EO product that is part of this EO
product (e.g. a phr:DataStrip is composed of one or more phr:Scene)

linkedWith: in O&M EOP used to link another EO product (e.g. ERS1 and ERS2
interferometric pair)
3.3.4.2 Type ProcessingInformation

processingCenter (Processing center code. Possible values are mission specific and
should be retrieved using codeSpace): 5-04

method (Method used to compute datalayer. (e.g. Kalman filtering, ROSE)) &
methodVersion (Method version (e.g. 1.0)): 7-01
processorName (Processor software name (e.g. FastROSE)) & processorVersion
(Processor software version (e.g. 1.0)): 7-05


processingLevel (Processing level applied to the product): 7-06

nativeProductFormat (Native product format): 7-07 + 7-08
The ProcessingInformation is sufficiently mapped.
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3.3.4.3 Quality Information
QualityInfo is unsufficiently considered in WIGOS

productQualityDegradation (Quality degradation percentage (i.e. uom=’%’): related
to single PDU´s and so need not to be considered

productQualityDegradationQuotationMode (Indicator to know how the quality
degradation percentage has been calculated. Values : AUTOMATIC, MANUAL): 804

productQualityStatus (Indicator that specifies whether the product quality is degraded
or not. This optional field shall be provided if the product has passed a quality check.
Values: DEGRADED, NOMINAL). Related to single PDU´s and so need not to be
considered

productQualityDegradationTag (Contains further textual information concerning the
quality degradation. It shall be provided if eop:productQualityStatus value is
DEGRADED. Possible values are mission specific and should refer to mission/ground
segment dedicated codeSpace. Example of values could be "RADIOMETRY" or
"GEOLOCATION".): Related to single PDU´s and so need not to be considered

productQualityReportURL reference to an external quality report file: Related to
single PDU´s and so need not to be considered
3.3.5 EarthObservationEquipment
3.3.5.1 Acquisition
That information maybe be too specific for metadata describing mainly collections of EO
data and not single PDU´s.
Elements like orbitNumber or ascendingNodeLongitude are closely related to single PDU´s.
Some information are further related to specific types of products, e.g.
illuminationZenithAngle or instrumentAzimuthAngle (mainly related to SAR products).
But a few elements should be checked if those may make sense to include in WIGOS like:

orbitDirection (Acquisition orbit direction. Values: ASCENDING, DESCENDING)

orbitDuration
(Actual orbit duration in milliseconds)
3.3.5.2 Platform


platformShortName (Platform short name (e.g. PHR)): 3-03
platformSerialIdentifier (Platform serial identifier (e.g. for PHR : 1A): 3-04/3-06
Ok so far. Missing:

platformOrbitType High level characterisation of main mission types taken from a
codelist. Values:GEO,LEO
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3.3.5.3 Instrument / Sensor
Mostly sufficiently considered:

instrumentDescription: 5-09

InstrumentShortName (Instrument (Sensor) name): 5-09

InstrumentType (Instrument type): 5-09

sensorType (Sensor type based on codelist.Values:
- OPTICAL
- ALTIMETRIC
- ATMOSPHERIC
- LIMB): 5-09 ?

SensorOperationalMode (Sensor mode. Possible values are mission specific and
should be retrieved using codeSpace): too mission specific (?)

SensorResolution (Sensor resolution): 6-05

SensorSwathIdentifier (Swath identifier (e.g. Envisat ASAR has 7 distinct swaths
(I1,I2,I3...I7) that correspond to precise incidence angles for the sensor). Value list
can be retrieved with codeSpace.): Related to single PDU´s and so need not to be
considered

SensorWavelengthInformation/DiscreteWavelengths (List of discrete wavelengths
observed in the product (gml:MeasureList)): Maybe just related to single PDU´s and
so need not to be considered ? Maybe 1-01 ?

SensorWavelengthInformation/endWavelength (End of the observed wavelength
range (gml:Measure)): Maybe just related to single PDU´s and so need not to be
considered ? Maybe 1-01 ?

SensorWavelengthInformation/spectralRange (The observed Spectral Range: Values:INFRARED- NEAR-INFRARED- UV- VISIBLE- OTHER): Maybe 1-01 ?
SensorWavelengthInformation/startWavelength (Start of the observed wavelength
range (gml:Measure)) : Maybe just related to single PDU´s and so need not to be
considered ? Maybe 1-01 ?


- RADAR
SensorWavelengthInformation/wavelengthResolution (Spacing between consecutive
wavelengths (gml:Measure): Maybe 1-01 ?
3.3.6 Footprint (FeatureOfInterest)

multiExtentOf (Acquisition footprint coordinates, described by a closed polygon (last
point=first point), using latitude, longitude pairs.
Expected structure is
gml:Polygon/gml:exterior/gml:LinearRing/gml:posList): . 1-04

centerOf (Acquisition center coordinates): ??

orientation (Determines the orientation of the coordinate pairs for the exterior
boundary of the footprint polygons. Possible values are CW (clockwise), counterclockwise (CCW) or OTHER (unspecified orientation). Note that this property is
only to be provided for footprints that do not follow the normal counterclockwise for
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exterior boundaries convention as defined in [OGC06-103r4]. If the property is not
provided, a CCW orientation for the exterior boundary will be assumed.):
3.3.7 EarthObservationResult
As single PDU will not be described this is not of that importance….especially
ProductInformation could be skipped
Maybe some sample BrowseInformation (Quicklook, Thumbnail) could be interesting
What about MaskInformation ??
4
RESULT SUMMARY
The WIGOS standard covers most of the necessary elements for describing a Satellite
observation as a complement to WMO Discovery metadata. The WIGOS metadata can focus
on describing the instrument characteristics and capacitiy as well as the earth observation
qualities. Links should be established between the WMO Discovery metadata and WIGOS
metadata to allow users to have access to the fully comprehensive information regarding a
particular products. If WIGOS is intended to describe individual product instances or PDU,
some elements should be added to fully describe the PDU instances.
The WIGOS information model allows to describe the core Earth Observation elements but
some parts such as for instance Orbit information and data quality should be extended to
allow providing enough information. Links to associated data access services or the
corresponding WMO Discovery Metadata containing that information could also be added to
allow users to have a fully comprehensive source of information regarding a particular
product. Additionally references to identifiers associated to the products such as Digital
Object Identifiers (DOIs) should be added.
A summary below is given what is covered by WIGOS and potential gaps that would require
improvements/extentions.
1. The observation core (in the materialization of eop:EarthObservation) is sufficiently
considered by WIGOS metadata.
2. At minimum two kinds of identifier for the dataset should be taken into account: a URI
(for being able to deference and link the dataset) and a DOI.
3. The descriptions of different WIGOS metadata elements need an update when those shall
also be used for EO related information: e.g. the description of a “platform” needs to be
extended to that it also covers a “satellite”…
4. Elements to describe how to get access to the data are fully missing in WIGOS metadata.
It should be considered that either general access points could be addressed (e.g. Order
Apps) or links (URLs) to direct download datasets.
5. Maybe more elements are needed in WIGOS metadata to describe the abstract and
keywords. This is in OGC/HMA usually overtaken by ISO19115 elements. But it needs
to be limited to really basic information to not overload it especially for the case that in
the future WIGOS metadata may also be used to describe single EO products.
6. Some O&M EOP elements (related to general EO metadata) are sufficiently mapped or
are just related to PDUs or product instances(e.g. acquisitionDate, archivingDate):
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a. Other elements related to general EO metadata is NOT sufficiently mapped (e.g.
statusSubtype).
b. The ProcessingInformation is sufficiently mapped.
c. QualityInfo related to single PDUs is insufficiently considered in WIGOS, e.g.
productQualityDegradation,
productQualityStatus,
productQualityDegradationTag, productQualityReportURL
7. In the EarthObservationEquipment context:
a. Acquisition information maybe be too specific for metadata describing mainly
collections of EO data and not single PDU´s (e.g. orbitNumber or
ascendingNodeLongitude). But a few elements should be checked if those may
make sense to include in WIGOS like: orbitDirection or orbitDuration
b. Platform and Instrument/Sensor seem sufficiently be covered. platformOrbitType
may be interesting to include. Other missing elements are very specific and more
related to PDUs like SensorSwathIdentifier, SensorWavelengthInformation /
DiscreteWavelengths etc…
8. Footprint is covered
9. The EarthObservationResult context is more related to single PDU´s
a. especially ProductInformation could be skipped if no single PDU´s shall be
described.
b. Maybe some sample BrowseInformation (Quicklook, Thumbnail) could be
interesting
c. Mask Information is not covered and it should be assessed if it is needed
information
For the future, it would be important to have some hooks to link to related information. In
HMA E&P we have:

parentIdentifier: used to link to the collection identifier. Could be interesting in
WIGOS to link e.g. to more general information (e.g. CGMS/WMO-Core metadata)

subsetOf: used to link to the “father” EO product (e.g. a phr:Scene is a subset of a
phr:DataStrip)

composedOf: used to link to an EO product that is part of this EO product (e.g. a
phr:DataStrip is composed of one or more phr:Scene)
linkedWith: used to link another EO product (e.g. ERS1 and ERS2 interferometric pair)
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