RADIOMETRY (GeM+)
Section [ATTRIBUTE_BANDA:NOM_CAMP:BAND] (REL file)

Name of GeM+ entry: Minimum wavelength
Name of REL file key: MinimumWavelength

Description and considerations: The lowest sensitive wavelength of the sensor that has acquired the band.

This corresponds to the minValue entry in the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > minValue).

Follows the proposal of: ISO

Obligatory according to ISO: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Maximum wavelength
Name of REL file key: MaximumWavelength

Description and considerations: The highest sensitive wavelength of the sensor that has acquired the band.

This corresponds to the maxValue entry of the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > maxValue).

Follows the proposal of:ISO

Obligatory according to ISO: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Peak Response
Name of REL file key: PeakResponse

Description and considerations: the wavelenght for which the sensor's response is maximum. This value must be in the interval between the minimum and maximum wavelengths.

This corresponds to the peakResponse entry of the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > peakResponse).

Follows the proposal of: ISO

Obligatory according to ISO: Yes if the minimum and maximum wavelengths have been documented.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Wavelength units
Name of REL file key: unitatsWavelengh

Description and considerations: the units in which the maximum and minimum wavelengths are expressed.

This corresponds to the units entry in the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > units).

Follows the proposal of: ISO

Obligatory according to ISO: Yes if the minimum, maximum or peak response wavelengths have been documented.

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Bits per value
Name of REL file key: BitsPerValue

Description and considerations: the number of bits that are used to store the values of each pixel in a band. It is possible to store a value between 0 and 255.

This corresponds to the bitsPerValue entry of the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > bitsPerValue).

Follows the proposal of: ISO

Obligatory according to ISO: No.

Cardinality: 1

Key type: N

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Tone gradation
Name of REL file key: ToneGradation

Description and considerations: the number of discrete values present in the raster.

This is not exactly the same as Bits per Value since, for example, a sensor can have a scale of radiances between 0 and 100 even though there are 7 bits per pixel (upto 128 possible values). In this case the real values in the raster will vary between 0-100 (and the tone gradation will be 101). The value stored in tone gradation must therefore be less than or equal to two raised to the power of Bits per value.

According to the ISO definition this key informs the user about the number of values used to scale the data and for this reason it seems that it should only take into account valid values and, therefore, if there exists a NODATA value this should not be counted. Also for this reason if the NODATA value is defined, the value stored in Tone Gradation must be less than or equal to 2 raised to the power of Bits per value less 1 (for the NODATA value). In the case of real and double precision rasters the bits are not interpreted in the same way so any value is permitted for this metadata entry.

This corresponds to the toneGradation entry in the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > toneGradation).

Follows the proposal of: ISO

Obligatory according to ISO: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Calibration type
Name of REL file key: CalibRadiom

Description and considerations: establishes the type of sensor calibration or how the conversion to radiances from DN has been performed.

This can take the following values:

• unknown: the type of calibration is unknown but the metadata defining the calibration may nevertheless be documented (parameters of the calibration line, radiance maximum, minimum and units).
• high gain
• low gain
• not applied: there are no radiance calibration parameters. In this case it is not possible to document the other metadata entries defining the calibration (parameters of the calibration line, radiance maximum, minimum and units).

Follows the proposal of: GeM+

Obligatory according to GeM+: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Scale factor
Name of REL file key: DN2L_ScaleFactorCoefficient

Description and considerations: the slope of the calibration line used to convert from DN to radiances.

This corresponds to the scaleFactor entry in the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > scaleFactor).

Follows the proposal of: ISO

Obligatory according to ISO: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Offset coefficient
Name of REL file key: DN2L_OffsetCoefficient

Description and considerations: The offset coefficient of the calibration line used to convert from DN to radiances. It is equivalent to the radiance of a pixel with a DN equal to zero.

This corresponds to the offset entry in the MD_Band section of the ISO standard (MD_Metadata > MD_ContentInformation > MD_CoverageDescription > MD_RangeDimension > MD_Band > offset).

Follows the proposal of: ISO

Obligatory according to ISO: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Minimum Radiance
Name of REL file key: MinL

Description and considerations: The minimum radiance represented by the image values (DN).

Follows the proposal of: GeM+

Obligatory according to GeM+: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Maximum Radiance
Name of REL file key: MaxL

Description and considerations: The maximum radiance represented by the image values (DN).

Follows the proposal of: GeM+

Obligatory according to GeM+: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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Name of GeM+ entry: Radiance units
Name of REL file key: unitatsL

Description and considerations: Radiance units represented by the image values (DN) if the defined calibration line is applied as defined by the slope and the offset.

Follows the proposal of: GeM+

Obligatory according to GeM+: No

Cardinality: 1

Key type: C

AppliesToLayer: Yes
AppliesToSeries: No (contains information on the layer)

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