ckwriter produces a NAIF compatible SPICE CK kernel from one or
more ISIS cube files. The cube files must have been initialized with
the spiceinit program. They may also have undergone pointing
adjustments by jigsaw or some other (bundle) adjustment
application.
The contents of the CK kernel are extracted from the ISIS
InstrumentRotation Table (BLOB) in the ISIS file. This Table
is created by the spiceinit application and its contents
further modified by ISIS pointing (bundle) adjustments. The contents
may not be in a state that can be written directly to the kernel. They
must be converted (i.e., rotated) into the proper reference frames
utilized by each mission/instrument. These frames are specified in
the ISIS specific instrument addendum kernels (IAK). For example, the
HiRISE instrument addendum kernel is
$ISIS3DATA/mro/kernels/iak/hiriseAddendum006.ti. The keyword ending
in CK_FRAME_ID is the instrument frame stored in the CK kernel.
The keyword ending in CK_REFERENCE_ID is the CK reference
frame. These frames will vary from mission to mission.
Users may provide one or more ISIS cube files to the application.
Each file is written to the CK kernel as its own segment. The
ProductId from the ISIS label is used as the NAIF SEGMENT ID.
This information along with other information pertaining to the
ISIS file and image data is recorded in the kernel comment section.
A general description of the CK kernel contents is provided by the
application but the user can provide their own comment for the kernel
if it is not sufficient in the COMFILE parameter.
Provided in every CK kernel file created is the complete list of all
the SPICE kernels, DEMs and extras loaded by
spiceinit. In order to ensure the same geometric properties
when using this kernel, the same kernels listed for the ISIS file
segment must be supplied in any subsequent run of
spiceinit. The CamVersion value listed refers to the
version of the ISIS camera model in use at the time the CK data was
created. Any subsequent code changes to the ISIS camera model may
result in different geometric properties of the image.
The following is an example of the contents of the comment section in
the resulting CK kernel:
****************************************************************************
USGS ISIS (ckwriter) Generated CK Kernel
Created By: kbecker
Date Created: 2010-12-07T01:27:42
****************************************************************************
Orientation Data in the File
-----------------------------------------------------------------------
This file contains orientation and potentially derived angular
rates (where possible/specified).
Status
-----------------------------------------------------------------------
This kernel was generated for the purpose of storing C-Smithed
pointing updates generated through ISIS processing techniques
(control nets, jitter analysis, etc...). These CK kernels
are intended to mimick CKs provided by individual mission
(NAV teams).
Pedigree
-----------------------------------------------------------------------
This file was generated by an automated process. The ISIS
application ckwriter was used to read CK kernel data
contained within an ISIS cube file. It then writes it as an
individual segment in the CK. Hence, a list of files can be
written to a single CK kernel. However, mixing the instruments
contained in a single CK kernel is discouraged.
Individual segments coming from files will have a single record
written for the center of the exposure (time) for framing
instruments or a record/image line for line scan instruments.
Creating type 3 CK kernels must contain at least 3 records for
framing instruments to avoid roundoff error for the center of the
exposure time of an image. Framing instruments should pad time
using the spiceinit application options.
Angular Rates
-----------------------------------------------------------------------
This kernel may or may not contain angular velocity vectors. Efforts
are made to preserve and provide angular velocities where they
originally existed.
Usage Note
-----------------------------------------------------------------------
To make use of this file in a typical SPICE based application,
you must supply a leapseconds kernel, a mission spacecraft clock
kernel, and the instrument/spacecraft frame kernel. These files
provide the supporting ancillary data to properly query this
C-kernel for attitude content. They should be the same kernels that
were originally used to initialize the image.
Segments in this file are actually individual ISIS files where the
internally cached SPICE data is extracted and transformed into the
appropriate content to satisfy NAIF's SPICE kernel storage
requirements. The contents of this kernel are summarized below.
Segment (by file) Summary
-----------------------------------------------------------------------
The follow sections describe each segment in this CK kernel. Each
segment is a file in the input list. When running ISIS spiceinit,
the kernels listed for each file should be supplied to ensure proper
geometry can be reproduced accurately.
-----------------------------------------------------------------------
File: PSP_001446_1790_RED2_0.cub
ProductId: PSP_001446_1790_RED2_0
StartTime: 2006-11-17T03:27:53.211
EndTime: 2006-11-17T03:27:54.912
Instrument: HIRISE
Target: Mars
InstrFrame: MRO_SPACECRAFT
RefFrame: MRO_MME_OF_DATE
Records: 18
HasAV: YES
CamVersion: 1
Kernels:
$mro/kernels/spk/mro_psp1.bsp
$mro/kernels/ck/mro_sc_psp_061114_061120.bc
$mro/kernels/fk/mro_v14.tf
$base/kernels/spk/de405.bsp
$base/kernels/pck/pck00009.tpc
$mro/kernels/ik/mro_hirise_v11.ti
$mro/kernels/iak/hiriseAddendum006.ti
$base/kernels/lsk/naif0009.tls
$mro/kernels/sclk/MRO_SCLKSCET.00041.65536.tsc
$base/dems/molaMarsPlanetaryRadius0004.cub
Contents of the comment section in the CK kernel can be replaced by
the user if desired. The individual file segment information will
always be written to the label.
To extract the contents of the SPICE CK kernel it is recommended you
use the SPICE commnt utility. The form of the command to
extract the contents is commnt -r PSP_001446_1790_RED2_0.bc.
This SPICE utility can be downloaded from NAIF's web site from one of
the supported systems at the location
ftp://naif.jpl.nasa.gov/pub/naif/utilities.
The SUMMARY parameter is provided as a file name that will contain the
comments section of the output CK kernel file. This can be used in
addition to or in lieu of the TO parameter. Getting the contents of
the comment section of the NAIF CK SPICE kernel in the TO file
requires the NAIF utility program, commnt .
To use the newly created CK SPICE kernel in the ISIS environment, you
use the spiceinit program providing, at a minimum, the CK
kernel created by ckwriter in the CK parameter. The
basic command would be:
spiceinit from=PSP_001446_1790_RED2_0.cub
CK=PSP_001446_1790_RED2_0.bc
This would be the best case scenario should all the other kernels
listed in the comments be selected. If they are not the same, then
you will need to resort to explicitly providing all of them in the
spiceinit command line. Here is the command using the above
list for PSP_001446_1790_RED2_0:
spiceinit from=PSP_001446_1790_RED2_0.cub
LS='$base/kernels/lsk/naif0009.tls'
PCK='$base/kernels/pck/pck00009.tpc'
TSPK='$base/kernels/spk/de405.bsp'
IK='$mro/kernels/ik/mro_hirise_v11.ti'
SCLK='$mro/kernels/sclk/MRO_SCLKSCET.00041.65536.tsc'
CK=PSP_001446_1790_RED2_0.bc
FK='$mro/kernels/fk/mro_v14.tf'
SPK='$mro/kernels/spk/mro_psp1.bsp'
IAK='$mro/kernels/iak/hiriseAddendum006.ti'
SHAPE=USER
MODEL='$base/dems/molaMarsPlanetaryRadius0004.cub'
See the NAIF website for more information:
http://naif.jpl.nasa.gov/naif.
