ISIS 2 Documentation
The following describes the data columns contained in the header of each spectrum stored in an Instrument Spectral Library. A description of this header structure is written to the label of an Instrument Spectral Library file in the SPECTRAL_HEADER_DEFINITION GROUP of keywords within the object description for the QUBE object that contains the library spectra. (See example ISL label in Appendix F.) The data columns listed below include the required and optional columns defined by the S_INIT_HREC routine. Columns denoted with an asterisk (*) are required in the spectral header. All others are optional. Note that each of the data columns described below contains a scalar data value rather than an array of values. However, an application could define additional optional columns that contain arrays of values as well as scalar values. Byte Column Name Type Size Description ------------------- --------- ---- -------------------------------- *SPECTRUM_TYPE_ID INTEGER 4 Specifies type of stored primary spectrum and secondary data arrays. Note that primary spectra type codes are restricted to positive values whereas secondary data array type codes are restricted to negative values. -6 - count of valid pixels in averaged group -5 - maximum of averaged group -4 - minimum of averaged group -3 - standard deviation of averaged group -2 - uncertainty -1 - imaginary part of any complex type defined by its primary ID 0 - empty slot - reserved for system usage 1 - real part of complex index of refraction 2 - radiance 3 - reflectance 4 - reflectance*solar spectrum 5 - transmission 6 - transmission*solar spectrum 7 - absorption 8 - absorption coefficient 9 - emissivity 10 - instrument noise spectrum 11 - unclassifiable MATERIAL_STATE_ID INTEGER 4 Specifies the state of the observed medium 0 - unknown 1 - gas 2 - liquid 3 - solid, polished 4 - solid, rough 5 - solid, particulate 6 - natural surface (remote sensed) 7 - suspended droplets (clouds) MATERIAL_PRESSURE REAL 4 Specifies the [surface] pressure of a gas in PASCALS MATERIAL_TEMPERATURE REAL 4 Specifies the sample temperature in KELVIN MATERIAL_PATH_LENGTH REAL 4 Specifies the path length in a fluid or the particle size of a particulate solid in METERS. For rough or polished solids, this is the mean crystal size if known. *SPECTRUM_NAME CHARACTER 40 The name of the spectrum. Unique for all primary spectra within the library file. SOURCE_TYPE_ID INTEGER 4 Code that helps identify where the spectrum originated 1 - laboratory 2 - Flight instrument, e.g., via "cv" or "cubespec" or other such applications 3 - theory 4 - others (?) SOURCE_NAME CHARACTER 48 Name of the source where the spectrum originated. Dependent upon SOURCE_TYPE_ID as to what is stored in this column. For SOURCE_TYPE_ID=1, 3 and 4, SOURCE_NAME will contain the name of the person who generated the spectrum. For SOURCE_TYPE_ID=2, the name of the file from which the spectrum was generated can be found here. SOURCE_INDEX_1 INTEGER 4 Based on the value of SOURCE_TYPE_ID, this column gives further information about the spectrum source. For SOURCE_TYPE_ID=1, the spectrum is from a library generated from laboratory observations and this column contains the library number. For SOURCE_TYPE_ID=2, source is from applications such as "cv"/"cubespec" and this column will contain the SAMPLE number from a file where the spectrum was obtained. (This will usually be the CENTER of the averaged area.) For SOURCE_TYPE_ID=3, this column can be used to refer to the run number, for example. SOURCE_INDEX_2 INTEGER 4 A second column of information about the spectrum source. For SOURCE_TYPE_ID=1, this column specifies the location or index of the spectrum from the library. For SOURCE_TYPE_ID=2, this column specifies LINE number from a file where the spectrum was obtained. (This will usually be the CENTER of the averaged area.) For SOURCE_TYPE_ID=3, this column can be used for the curve number. SOURCE_REGION_WIDTH INTEGER 4 For SOURCE_TYPE_ID=1 and 3, this column is undefined. For SOURCE_TYPE_ID=2, this column specifies the width of the box size in SAMPLEs used in "cv" or "cubespec" to generate the spectrum. SOURCE_REGION_HEIGHT INTEGER 4 For SOURCE_TYPE_ID=1 and 3, this column is undefined. For SOURCE_TYPE_ID=2, this column specifies the height of the box size in LINEs used in "cv" or "cubespec" to generate the spectrum. AVERAGED_SPECTRUM_COUNT INTEGER 4 This specifies the total number of observed or original spectra averaged to result in this spectrum. CHEMICAL_DESCRIPTION CHARACTER 60 ASCII representation of chemical composition formula of the material. (Also available for comment.) INCIDENCE_ANGLE REAL 4 Angle in DEGREES at the observed point between a vector to the sun and a vector normal to the surface. EMISSION_ANGLE REAL 4 Angle in DEGREES at the observed point between a vector to the observer and a vector normal to the surface. PHASE_ANGLE REAL 4 Angle in DEGREES at the observed point between a vector to the sun and a vector to the observer. *DATE_TIME CHARACTER 20 Data and time the spectrum or entry was generated. It has the ISO form "YYYY-MM-DDTHH:MM:SS", the ISIS standard. MEAN REAL 4 Computed mean of the spectrum STANDARD_DEVIATION REAL 4 Computed standard deviation of the spectrum *PARENT_SPECTRUM_INDEX INTEGER 4 Is the index of a spectrum contained in this library to which this spectrum is related or linked. A value 0 specifies this is a primary or root spectrum in a chain of related data arrays. *CHILD_SPECTRUM_INDEX INTEGER 4 Is the index of a spectrum contained in this library that is 'chained' to this spectrum and related to the primary or root spectrum in some way. A value of 0 specifies that this is the last spectrum in the chain. This and the previous column creates what is known as a double-linked list of primary spectrum and related secondary data arrays.