hical

  For:

  H  = dark current and offset corrected image, output of hiclean2
  B = intra-channel dark current correction (TDI and BIN dependent)
  A = intra-channel gain correction (TDI and BIN dependent)
  G  = global gain correction, normalizes CCD/channels
  L  = observation line time
  I  = I/F conversion factor at Sun-Target distance of 1.5 AU
  AU = Mars-to-Sun distance (AU) at time of observation
  Z  = radiometrically corrected image in I/F units

  The correction is:
  
  Z = (( (H/L -B) *A)*G /(I*(1.5/AU)2)
      

Files: FROM

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Description

The name of the cube to which the correction will be applied. The correction will apply to every non-special pixel in the image. The hiclean2 application is ran on this file creating a temporary file. This temporary file is then input into hical that applies further radiometric calibration. The temporary file is then deleted.

Files: CONF

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Description

This important file provides all parameters used in the calibration process. It contains references to calibration matrices (such as flat fields, instrument gains, etc...), label keywords and parameter constants used in the radiometric calibration process.

The format of this PVL file is highly flexible for managing HiRISE calibration data. It provides three main elements in this interface: matrices, scalars (or constants) and keywords.

Matrices are currently multi-band ISIS cube files that contain one line and up to 1024 samples. There are expected to be 28 bands in each one of thes calibration matrices, one for each CCD channel. There are 14 different CCDs with 2 channels each for a total of 28 channels. (Note that channels are the basic HiRISE image product where calibration is applied.) There will always be one line for these cubes since HiRISE detectors are line scan instruments. There will be a minimum of 128 (for summing mode of 16) and a maximum of 1024 (summing mode of 1) samples in these cubes. The content of these matrix files are dependant upon summing mode and the time delay integration (TDI) mode used during image acquisition. TDI allows varying number of line scans, in conjunction with exposure time, to pass over the same point on the surface of Mars to increase the signal-to-noise ration (SNR) as well as resolution. There are 4 selectable modes of TDI: 128, 64, 32 and 8. Coupled with 6 difference summing modes (1, 2, 3, 4, 8, and 16), there are at least 24 calibration cubes per set of matrices. These matrices are referenced as file paths of the form:

 A = $mro/calibration/matrices/A_TDI{TDI}_BIN{BIN}_????.cub
                

Here, {TD} and {BIN} correspond to the TDI and summming mode used during image acquisition, respectively. (More on how these values are determined is provided in the follow text.) Matrix variables are equated to file references using the Matrix keyword in the configuration file. Matrix file paths are also subjected to pattern replacement in the same fashion as profiles. This will minimize the content management aspect of the configuration file and encourage consistant file naming schemes.

In addition to Matrices, the PVL configuration file provides the the specification of constants or Scalars. These are evaluated as a single double floating point value as read directly from the configuration file. They have the following form:

 IFTdiBinFactor = 1.0
                

There can be any number of scalars specified via the Scalars keyword in the configuration file. These keywords must exist in the main object keyword section and/or in one or more Profiles that are subsequently loaded.

In addition to Matrices and Scalars, the configuration file provides a mechanism to map HiRISE label keywords to values that can be used in the calibration equation. Currently the equation is fixed as described in the program section, but plans are for different equations to be defined as needed to further provide flexibility and adaptability to the calibration process as needed. These keywords are defined as a named keyword in the label followed by an optional Group specification, which is typically always required. These keywords are defined in the Keywords Profile group. They are of the following form:

ScanExposureDuration = ("ScanExposureDuration", "Instrument")
                

This names the keyword ScanExposureDuration and specifies it is found in the ScanExposureDuration keyword in the Instrument group in the HiRISE image label. Keywords used in this manner are specified in the Keywords keyword in the configuration file.

The real power of the configuration file is its use of named Profiles. Profiles are groups of keywords that can be associated to a unique definition. The hical PVL configuration file consists of a single Hical object with numerous named Profile groups. Each of the Profile groups must contain a Name keyword that uniquely identifies it within the Hical object. This allows us to create Profiles that pertain to particular combinations of filter (RED, IR, BG), CCD (RED0-9, IR10/11, or BG12/13), TDI (128, 64, 32, 8), BIN (1, 2, 3, 4, 8, 16) or CHANNEL (1 or 2). These values are determined from the content of the HiRISE label. Combinations of profiles that are added after the initial default are specified in the ProfileOptions keyword. Profile combinations can consist of any combination or use of these defined values. These defined values are specified as or with the Name keyword in Profile groups delimited by curly braces. Given this definition one can specify a particular group of calibration parameters for a specific CCD channel with the pattern {FILTER}{CCD}_{CHANNEL}. Then, one can define a special collection of calibration matrices, keywords or scalars for any one (or none) of the filters. So, for the problematic BG13, you can have a named profile called BG13_1 whose keywords in the profile are loaded when calibrating a BG13_1 channel, thus overriding any defaulted keywords. Should named profiles using this option not exist, they are ignored. Also, Profiles specified in this manner are loaded in the order specified in the ProfileOptions keyword, thus creating a hierarchy of calibration specification configurations.

Below is an example of a complete PVL configuration file that demonstrates some of the features described:

Object = Hical

/* Default profile name */
  Name           = "HiMatrices"
  DefaultProfile = "HiMatrices"

/* Define matrices, constants and keywords */
  Matrices = ("A", "B", "G")
  Scalars  = ("FilterGainCorrection", "IFTdiBinFactor")
  Keywords = ScanExposureDuration

/* Additional profile combinations and order loaded in hierarchy */
  ProfileOptions = ("{FILTER}", "TDI{TDI}", "BIN{BIN}", "TDI{TDI}/BIN{BIN}",
                    "{FILTER}{CCD}_{CHANNEL}", 
                    "{FILTER}{CCD}_{CHANNEL}/TDI{TDI}/BIN{BIN}")

/* Set defaults.  All subject to profile filtering operations as defined */
/* above */
  A = "$mro/calibration/matrices/A_TDI{TDI}_BIN{BIN}_????.cub"
  B = "$mro/calibration/matrices/B_TDI{TDI}_BIN{BIN}_????.cub"
  G = "$mro/calibration/matrices/G_TDI{TDI}_BIN{BIN}_????.cub"

/* I/F correction for tdi/bin - currently set at 1.0 for all tdi/bin */
/* combinations.  One can use the ProfileOptions scheme when they become */
/* better defined */
  IFTdiBinFactor = 1.0

/* Label Keyword maps.  Order/form:  Keyword = (Keyword[, Group]) */
  Group = Profile
    Name = Keywords
    ScanExposureDuration = ("ScanExposureDuration", "Instrument")
  End_Group

/* Here are the filter profiles.  All keywords that pertain to a filter set */
/* should be specified here.  FilterGainCorrection are I/F corrections in */
/* units of DN/s */
  Group = Profile
    Name = RED
    FilterGainCorrection = 175613029.0
  End_Group

  Group = Profile
    Name = IR
    FilterGainCorrection  =  58571990.0
  End_Group

  Group = Profile
    Name = BG
    FilterGainCorrection  =  93575312.0
  End_Group

End_Object
            

The filter profiles each contain a scalar constant of the same name for each of the three filter sets. The ProfileOrder keyword contains the {FILTER} pattern that will select the appropriate filter gleened from the label. Other profiles that satisfy the remaining patterns are excluded but can be added when necessary.

The final resutling matrices, constants and keywords used in the calibration equation are recorded in the RadiometricCalibration group of the output label.

Files: TO

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Description

Use this parameter to specify the name of the output cube. If you do not include an extension of ".cub" it will be added automatically.

Options: PROFILE

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Description

This is the name of a named Profile group in the hical matrix configuration file that users can choose for specific selection of HiRISE calibration parameters and matrix files.

Note that when using this option, the additional profiles specified in the ProfileOptions key are not applied. This option is primarily to assist in testing and specific application conditions.