KPL/IK Deep Impact High Resolution Imager Instrument Kernel =========================================================================== This instrument kernel (I-kernel) contains optics and detector geometric parameters of the High Resolution Imager (HRI) instrument mounted on the Deep Impact Flyby (DIF) spacecraft. Version and Date --------------------------------------------------------------------------- Version 1.0 -- September 13, 2005 -- Boris Semenov, NAIF/JPL Completed various sections including instrument overview, nominal parameters, frame-detector relationship diagram, optical distortion, etc. INS-*_CENTER keywords were replaced with INS-*_CCD_CENTER. Version 0.1 -- December 20, 2004 -- Boris Semenov, NAIF/JPL Re-defined FOVs using ``angular extent'' style and made FOV angular extents consistent with updated frame definitions. Version 0.0 -- April 13, 2001 -- Boris Semenov, NAIF/JPL Preliminary Version: --- TO BE USED ONLY FOR SOA TOOL DEMONSTRATION --- This version is based solely on [4], which, as of Rev 010216, did NOT contain complete set of information required to understand and define Deep Impact HRI Instrument parameters. Therefore, most of the sections of this IK file either contain target design values or no values at all (just place-holders identifying what items may be included later.) References --------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. ``C-kernel Required Reading'' 3. Deep Impact Frames Kernel, latest version 4. ``Deep Impact Instruments Requirements Specification'', 2001 February 16, M. Ensminger 5. ``Cassini ISS Geometric Calibration of April 2003'', W. M. Owen, Jr., May 9, 2003 6. E-mails providing DI camera distortion model parameters from Nick Mastrodemos, DI OPNAV team, 04/29/05 and 09/09/05 7. HRI description from the Deep Impact Project public Web site: http://deepimpact.jpl.nasa.gov/tech/hri.html Implementation Notes -------------------------------------------------------- User programs that need I-kernel data must `load' the I-kernel file, normally during program initialization. Loading the kernel using SPICELIB routine FURNSH causes the data items and their associated values present in the kernel to become associated with a data structure called the ``kernel pool''. Then a user's program can obtain the value(s) for any data item using the SPICELIB routines GDPOOL, GIPOOL and GCPOOL. See [1] for details. This file was created and can be updated with a text editor or word processor. Naming Conventions -------------------------------------------------------- All names referencing values in this I-kernel start with the characters ``INS'' followed by the NAIF DIF spacecraft ID number (-140) followed by the NAIF three digit HRI VIS instrument reference number (110) or HRI IR instrument reference number (120). The remainder of the name is an underscore character followed by the unique name of the data item. For example, the focal length of the HRI IR camera is specified by INS-140120_FOCAL_LENGTH The upper bound on the length of the name of any data item is 32 characters. If the same item is included in more then one IK file, or if the same item appears more than once within a single file, the latest value supersedes any earlier values. HRI Overview -------------------------------------------------------- From [7]: "The High Resolution Instrument (HRI), designed and built by Ball Aerospace & Technologies Corp., is the main scientific instrument on the flyby spacecraft. Comprised of a telescope with a 30 cm (11.8 inch) aperture, an infrared (IR) spectrometer, and a multi-spectral CCD camera, the HRI CCD camera will image the comet with less than 2 m (6 feet) per pixel scale when the flyby spacecraft is 700 km (420 miles) away. That is similar to resolving a car from across the state of Colorado. At this scale the crater that forms would be about 60 to 100 pixels across, looking something like the simulated image below. The IR spectrometer will take images with a per pixel scale of 10 m (33 feet) at closest approach. The HRI's science camera will provide five times higher resolution images than the Medium Resolution Instrument, making it ideal for viewing the comet's nucleus. It is the only one of the three instruments to feature a special imaging module called the Spectral Imaging Module (SIM), which allows it to view in color, white light, and infrared. The HRI is one of the largest instruments built to date for planetary science and the first of its kind, although it employs technologies from the Wide Field Camera 3, the next-generation imaging instrument that Ball Aerospace & Technologies Corp. developed for the Hubble Space Telescope." HRI Mounting Alignment -------------------------------------------------------- Refer to the latest version of Deep Impact Frames Definition Kernel ([3]) for the HRI frame definitions and mounting alignment information. HRI Optics Parameters -------------------------------------------------------- The following nominal HRI IR and VIS first order optical parameters are provided in [4]: ----------------------------------------------------------------- parameter IR VIS ----------------------------------------------------------------- Focal Length, mm 10500 10500 f/ratio f/35 f/35 FOV Angular Size, milliradians 2.53 x 0.01 2.0 x 2.0 IFOV, microradians/pixel 10 2 ----------------------------------------------------------------- The values in the keywords are given in the same units as in the table above except for angles which are given in radians. \begindata INS-140110_FOCAL_LENGTH = ( 10500 ) INS-140110_F/RATIO = ( 35 ) INS-140110_FOV_ANGULAR_SIZE = ( 0.002, 0.002 ) INS-140110_IFOV = ( 0.000002, 0.000002 ) INS-140120_FOCAL_LENGTH = ( 10500 ) INS-140120_F/RATIO = ( 35 ) INS-140120_FOV_ANGULAR_SIZE = ( 0.00253, 0.00001 ) INS-140120_IFOV = ( 0.00001, 0.00001 ) \begintext HRI FOV Definitions --------------------------------------------------------------------------- Both FOVs defined in this section are based on the nominal HRI detector FOV angular sizes provided in the Table in "HRI Optics Parameters" section above. The set of keywords in the following data section defines nominal HRI VIS FOV with respect to the DIF_HRI_VIS frame to be a rectangle with angular size of 2.0 by 2.0 milliradians centered about the boresight vector along +Z axis of DIF_HRI_VIS frame. \begindata INS-140110_FOV_FRAME = 'DIF_HRI_VIS' INS-140110_FOV_SHAPE = 'RECTANGLE' INS-140110_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-140110_FOV_CLASS_SPEC = 'ANGLES' INS-140110_FOV_REF_VECTOR = ( 0.0000000000000000 +1.0000000000000000 0.0000000000000000 ) INS-140110_FOV_REF_ANGLE = ( 0.001 ) INS-140110_FOV_CROSS_ANGLE = ( 0.001 ) INS-140110_FOV_ANGLE_UNITS = 'RADIANS' \begintext The set of keywords in the following data section defines nominal HRI VIS IR with respect to the DIF_HRI_IR frame to be a rectangle with angular size of 2.53 milliradian along slit/CCD lines (in YZ plane) by 0.01 milliradians across slit (in XZ plane) centered about the boresight vector along +Z axis of DIF_HRI_IR frame. \begindata INS-140120_FOV_FRAME = 'DIF_HRI_IR' INS-140120_FOV_SHAPE = 'RECTANGLE' INS-140120_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-140120_FOV_CLASS_SPEC = 'ANGLES' INS-140120_FOV_REF_VECTOR = ( 0.0000000000000000 +1.0000000000000000 0.0000000000000000 ) INS-140120_FOV_REF_ANGLE = ( 0.001265 ) INS-140120_FOV_CROSS_ANGLE = ( 0.000005 ) INS-140120_FOV_ANGLE_UNITS = 'RADIANS' \begintext HRI Optical Distortion Specification -------------------------------------------------------- This section provide optical distortion parameters for the HRI VIS and IR channels. HRI VIS Optical Distortion The following distortion model has been used by the DI OPNAV team for this camera during the mission (based on [5]; according to Bill Owen DI OPNAV used the same camera model as Cassini OPNAV): A 3d vector (P) in the camera frame is mapped into sample and line (S,L) coordinates by: ( X ) FL ( P(1) ) ( ) = ------ ( ) ( Y ) P(3) ( P(2) ) 2 2 2 R = X + Y ( dX ) ( X*R*R X*Y X*X ) ( E2 ) ( ) = ( ) ( E5 ) ( dY ) ( Y*R*R Y*Y X*Y ) ( E6 ) ( S ) ( Kx Kxy ) ( X + dX ) ( S0 ) ( ) = ( ) ( ) + ( ) ( L ) ( Kyx Ky ) ( Y + dY ) ( L0 ) where FL is the camera focal length in mm; the E(i) are coefficients of the cubic radial distortion and detector misalignment; the matrix K maps millimeters to pixels in the focal plane; and (S0,L0) are the focal plane coordinates of the optical axis. The following HRI VIS optical distortion parameters for this model were provided by Nick Mastrodemos, DI OPNAV ([6]): FL = 10497.6430 KMAT(1,1) = 4.761900E+01 KMAT(2,2) = 4.767262E+01 KMAT(2,1) = -6.958580E-03 EM(2) = -3.20483E-07 This data is provided in the keywords below: \begindata INS-140110_FOCAL_LENGTH = 10497.6430 INS-140110_KMAT = ( 4.761900E+01, -6.95858E-03, 0.0, 4.767262E+01 ) INS-140110_EM = ( -3.20483E-07, 0.0, 0.0 ) INS-140110_CCD_CENTER = ( 499.5, 499.5 ) \begintext This small fragment of SPICE-based FORTRAN code illustrated how these parameters can be loaded into an application and used to compute sample and line for a 3d vector defined in the camera frame, DIF_HRI_VIS: C C Retrieve loaded camera distortion parameters. C CALL GDPOOL ( 'INS-140110_FOCAL_LENGTH', 1, 1, N, FL, FND1 ) CALL GDPOOL ( 'INS-140110_KMAT', 1, 4, N, KMAT, FND2 ) CALL GDPOOL ( 'INS-140110_EM', 1, 3, N, EM, FND3 ) CALL GDPOOL ( 'INS-140110_CCD_CENTER', 1, 2, N, CNTR, FND4 ) C C Given 3d vector VECTOR in the camera frame, 'DIF_HRI_VIS', C compute ideal X and Y in sample/line space. C CALL VSCLG ( FL / VECTOR(3), VECTOR, 2, XYIDL ) C C Construct XYR2 matrix. C R2 = XYIDL(1)**2 + XYIDL(2)**2 XYRMAT(1,1) = XYIDL(1) * R2 XYRMAT(2,1) = XYIDL(2) * R2 XYRMAT(1,2) = XYIDL(1) * XYIDL(2) XYRMAT(2,2) = XYIDL(2) * XYIDL(2) XYRMAT(1,3) = XYIDL(1) * XYIDL(1) XYRMAT(2,3) = XYIDL(1) * XYIDL(2) C C Compute delta X and Y. C CALL MXVG ( XYRMAT, EM, 2, 3, XYDLT ) C C Compute line sample, SL (sample is the first element, C line is the second element.) C CALL VADDG( XYIDL, XYDLT, 2, XY ) CALL MXVG ( KMAT, XY, 2, 2, SLREL ) CALL VADDG( SLREL, CNTR, 2, SL ) HRI IR Optical Distortion IR optical distortion data was not available at the time when this IK file was made. HRI Detector Parameters -------------------------------------------------------- The following nominal HRI IR and VIS detector geometry parameters are provided in [4]: ----------------------------------------------------------------- parameter IR VIS ----------------------------------------------------------------- Pixel size, microns 105 21 (a) Number of pixels/mm 9.52380952 47.61904762 (a) Detector Size, physical 1024 by 512 (b) 1000 by 1000 Detector Array Center, physical n/a 499.5, 499.5 Detector Size, spatial 1 by 253 1000 by 1000 Detector Array Center, spatial 0.5, 126.5 499.5, 499.5 ----------------------------------------------------------------- (a) Nominal pixel sizes and numbers of pixels per mm for both detector were computed from the nominal focal length and IFOV provided in the ``HRI Optics Parameters'' section of this file. (b) 1024 by 512 IR detector is re-binned 2 x 2; the dimension containing 512 resulting pixels is the spectral resolution direction. The values in the keywords are given in the same units as in the table above. \begindata INS-140110_PIXEL_SIZE = ( 21.0 ) INS-140110_K = ( 47.61904762 ) INS-140110_PIXEL_SAMPLES = ( 1000 ) INS-140110_PIXEL_LINES = ( 1000 ) INS-140110_CCD_CENTER = ( 499.5, 499.5 ) INS-140120_PIXEL_SIZE = ( 105.0 ) INS-140120_K = ( 9.52380952 ) INS-140120_PIXEL_SAMPLES = ( 1 ) INS-140120_PIXEL_LINES = ( 253 ) INS-140120_CCD_CENTER = ( 0.5, 126.5 ) \begintext Relationship Between HRI Reference Frames, FOV, and Line/Sample Coordinates --------------------------------------------------------------------------- IR ``apparent'' FOV (spatial) with respect to the ``DIF_HRI_IR'' frame: 1 pixel/line --- *-* Line 1 ^ | | | | | | | | | +Zir | 2.53 mrad 253 |x-------------> +Xir | lines ||| | ||| | ||| V ||| --- *|* Line 253 | | +Yir V | 0.01 mrad | Boresight (+Z axis) |<----------------->| is into the page | | VIS ``apparent'' FOV with respect to the ``DIF_HRI_VIS'' frame:: 1000 pixels/line Line 1, Pixel 1 Line 1, Pixel 1000 --- *-------------------* ^ | | | | | | | | | | +Zvis | | 2.0 mrad | x-------------> +Xvis | | | | | 1000 | | | | lines | | | V | | | --- +---------|---------* | Line 1000, Pixel 1000 | +Yvis V | 2.0 mrad | Boresight (+Z axis) |<----------------->| is into the page | | Platform ID --------------------------------------------------------------------------- This number is the NAIF instrument ID of the platform on which the cameras are mounted. For both HRI detectors such platform is the spacecraft itself. \begindata INS-140120_PLATFORM_ID = ( -140000 ) INS-140110_PLATFORM_ID = ( -140000 ) \begintext