Filling Out the Old Spectral Dictionary Classes
The Spectral Discipline Dictionary contains classes used in the <Discipline_Area> of a label to describe the spectral characteristics of an array-type data object.
Contents
<Spectral_Characteristics>
This is the wrapper class that should be used to identifier all the classes relevant to a single spectral data object. If your product contains spectral objects with differing characteristics, then this class should be repeated once for each unique set of characteristics. You can also indicate that the characteristics in this class apply to more than one spectrum in the product, when that is the case.
<comment>
OPTIONAL
This is a place for additional free-format text description, as needed.
<bin_width_desc>
REQUIRED
You must supply a description of how the bin width for this spectrum was determined or calculated. Include the shape of the bin (gaussian, square wave, etc.) and define what "bin width" means (e.g., full width at half max).
<Local_Internal_Reference>
REQUIRED
This class provides a reference to a spectral data object elsewhere in the label. It may be repeated for each spectral data object sharing these characteristics.
<local_identifier_reference>
REQUIRED
The value of this attribute must correspond to the value of a <local_identifier> attribute in one of the spectral data objects defined elsewhere in this product label. Case counts.
<local_reference_type>
REQUIRED
This attribute must have the value spectral_characteristics_to_array_object
<comment>
OPTIONAL
A place for free-format text notes to users.
<Axis_Uniformly_Sampled>
OPTIONAL
- [But NOTE that at least one of <Axis_Uniformly_Sampled>, <Axis_Bin_Set>, and <Spectral_Lookup> must be specified.]
Use this class when the spectrum is uniformly sampled (i.e., in such a way that the bin centers and widths can be calculated) along an axis. You may repeat this class for each axis that is uniformly sample, if there is more than one.
<sampling_parameter_type>
REQUIRED
This attribute must contain one of the following values:
- frequency
- wavelength
- wavenumber
<sampling_interval>
REQUIRED
This value indicates the point-to-point difference in the sampling bins in units appropriate to the sampling_parameter_type. You must specify the correct unit as an XML attribute. So, for example:
<sampling_interval unit="Hz">52</sampling_interval>
...assuming the sampling_parameter_type was "frequency".
Valid units for each sampling_parameter_type are (spelling and case count):
- frequency
- Hz
- wavelength
- Angstrom
- cm
- m
- micrometer
- mm
- nm
- wavenumber
- 1/cm
- 1/m**
- 1/nm**
<bin_width>
REQUIRED
This attribute specifies the total width of a bin, in the same units as used for sampling_interval. You must specify the unit.
<first_center_value>
REQUIRED
This attribute is the value of the sampling parameter at the center of the first spectral bin, in the same units as used for sampling_interval. You must specify the unit.
<last_center_value>
REQUIRED
This attribute is the value of the sampling parameter at the center of the last spectral bin, in the same units as used for sampling_interval. You must specify the unit.
|
<Local_Internal_Reference>
REQUIRED
This class provides a reference to a specific axis named elsewhere in the label. It may be repeated in the extremely unlikely even that you have two axes which are uniformly sampled in precisely the same way.
<local_identifier_reference>
REQUIRED
The value of this attribute must correspond to the value of an <axis_name> attribute in one of the spectral data objects defined elsewhere in this product label. Case counts.
<local_reference_type>
REQUIRED
This attribute must have the value spectral_characteristics_to_array_axis
<comment>
OPTIONAL
A place for free-format text notes to users.
<Axis_Bin_Set>
OPTIONAL
- [But NOTE that at least one of <Axis_Uniformly_Sampled>, <Axis_Bin_Set>, and <Spectral_Lookup> must be specified.]
Use this class to describe the unique characteristics of each bin increment along a named spectral axis of the referenced array.
<Local_Internal_Reference>
REQUIRED
This class provides a reference to a specific axis named elsewhere in the label. It may be repeated in the extremely unlikely even that you have two axes which are uniformly sampled in precisely the same way.
<local_identifier_reference>
REQUIRED
The value of this attribute must correspond to the value of an <axis_name> attribute in one of the spectral data objects defined elsewhere in this product label. Case counts.
<local_reference_type>
REQUIRED
This attribute must have the value spectral_characteristics_to_array_axis
<comment>
OPTIONAL
A place for free-format text notes to users.
<Bin>
REQUIRED
This class gives the characteristics of an individual spectral bin. It should be repeated for each bin along the spectral axis (i.e., the number of <Bin> classes should be equal to the number of elements in the axis identified by the associated <Local_Identifier_Reference>.
<bin_sequence_number>
REQUIRED
This attribute indicates the the order of the bins along the specified axis.
|
<center_value>
REQUIRED
This attribute defines the center of the bin as either a frequency, wavelength, or wavenumber. You must specify an appropriate unit, and you must use the same unit for all center_value attributes and all bin_wdith values in this <Axis_Bin_Set> class.
Valid units for each type of bin are (spelling and case count):
- frequency
- Hz
- wavelength
- Angstrom
- cm
- m
- micrometer
- mm
- nm
- wavenumber
- 1/cm
- 1/m
- 1/nm
<bin_width>
REQUIRED
This attribute defines the full width of the particular spectral bin, in the same units as the preceding center_value. You must specify the unit.
<detector_number>
OPTIONAL
This attribute is for specifying the spectrometer detector number corresponding to this band in a spectral cube.
<grating_position>
OPTIONAL
This attribute is used for specifying grating position as a code number in spectral cubes. Typically these numbers start with 0 and increase with wavelength.
<original_bin_number>
OPTIONAL
This attribute is used for documenting spectral objects that represent a subset of some larger object. The number here corresponds to the <bin_sequence_number> of this band in the source data.
<Filter>
OPTIONAL
This class provides a way to identify a specific filter by name and/or number.
<filter_name>
OPTIONAL
This attribute contains a name (a string) by which the filter is known, either popularly or in any associated documentation.
<filter_number>
OPTIONAL
This attribute contains a number, specifically an integer, by which this filter is identified - typically a sequential number in a filter wheel.