ckcov_c

Index Page ckcov_c
A B C D E F G H I J K L M N O P Q R S T U V W X
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       void ckcov_c ( ConstSpiceChar    * ck,
                      SpiceInt            idcode,
                      SpiceBoolean        needav,
                      ConstSpiceChar    * level,
                      SpiceDouble         tol,
                      ConstSpiceChar    * timsys,
                      SpiceCell         * cover   )
#### Abstract
       Find the coverage window for a specified object in a specified CK
       file.
#### Required_Reading
       CELLS
       DAF
       CK
       TIME
       WINDOWS
#### Keywords
       POINTING
       TIME
       UTILITY
#### Brief_I/O
       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       ck         I   Name of CK file.
       idcode     I   ID code of object.
       needav     I   Flag indicating whether angular velocity is needed.
       level      I   Coverage level:  "SEGMENT" OR "INTERVAL".
       tol        I   Tolerance in ticks.
       timsys     I   Time system used to represent coverage.
       cover     I/O  Window giving coverage for `idcode'.
#### Detailed_Input
       ck             is the name of a C-kernel.

       idcode         is the integer ID code of an object, normally a
                      spacecraft structure or instrument, for which
                      pointing data are expected to exist in the specified
                      CK file.

       needav         is a logical variable indicating whether only
                      segments having angular velocity are to be considered
                      when determining coverage.  When `needav' is
                      SPICETRUE, segments without angular velocity don't
                      contribute to the coverage window; when `needav' is
                      SPICEFALSE, all segments for `idcode' may contribute
                      to the coverage window.

       level          is the level (granularity) at which the coverage
                      is examined.  Allowed values and corresponding
                      meanings are:

                         "SEGMENT"    The output coverage window contains
                                      intervals defined by the start and
                                      stop times of segments for the object
                                      designated by `idcode'.

                         "INTERVAL"   The output coverage window contains
                                      interpolation intervals of segments
                                      for the object designated by
                                      `idcode'.  For type 1 segments, which
                                      don't have interpolation intervals,
                                      each epoch associated with a pointing
                                      instance is treated as a singleton
                                      interval; these intervals are added
                                      to the coverage window.

                                      All interpolation intervals are
                                      considered to lie within the segment
                                      bounds for the purpose of this
                                      summary:  if an interpolation
                                      interval extends beyond the segment
                                      coverage interval, only its
                                      intersection with the segment
                                      coverage interval is considered to
                                      contribute to the total coverage.

       tol            is a tolerance value expressed in ticks of the
                      spacecraft clock associated with IDCODE.  Before each
                      interval is inserted into the coverage window, the
                      interval is intersected with the segment coverage
                      interval, then if the intersection is non-empty, it
                      is expanded by `tol': the left endpoint of the
                      intersection interval is reduced by `tol' and the
                      right endpoint is increased by `tol'. Adjusted
                      interval endpoints, when expressed as encoded SCLK,
                      never are less than zero ticks.  Any intervals that
                      overlap as a result of the expansion are merged.

                      The coverage window returned when tol > 0 indicates
                      the coverage provided by the file to the CK readers
                      ckgpav_c and ckgp_c when that value of `tol' is
                      passed to them as an input.

       timsys         is a string indicating the time system used in the
                      output coverage window.  `timsys' may have the
                      values:

                          "SCLK"    Elements of `cover' are expressed in
                                    encoded SCLK ("ticks"), where the
                                    clock is associated with the object
                                    designated by `idcode'.

                          "TDB"     Elements of `cover' are expressed as
                                    seconds past J2000 TDB.

       cover          is an initialized CSPICE window data structure.
                      `cover' optionally may contain coverage data on
                      input; on output, the data already present in `cover'
                      will be combined with coverage found for the object
                      designated by `idcode' in the file `ck'.

                      If `cover' contains no data on input, its size and
                      cardinality still must be initialized.
#### Detailed_Output
       cover          is a CSPICE window data structure which represents
                      the merged coverage for `idcode'. When the coverage
                      level is "INTERVAL", this is the set of time
                      intervals for which data for `idcode' are present in
                      the file `ck', merged with the set of time intervals
                      present in `cover' on input.  The merged coverage is
                      represented as the union of one or more disjoint time
                      intervals.  The window `cover' contains the pairs of
                      endpoints of these intervals.

                      When the coverage level is "SEGMENT", `cover' is
                      computed in a manner similar to that described above,
                      but the coverage intervals used in the computation
                      are those of segments rather than interpolation
                      intervals within segments.

                      When `tol' is > 0, the intervals comprising the
                      coverage window for `idcode' are expanded by `tol'
                      and any intervals overlapping as a result are merged.
                      The resulting window is returned in `cover'. The
                      expanded window in no case extends beyond the segment
                      bounds in either direction by more than `tol'.

                      The interval endpoints contained in `cover' are
                      encoded spacecraft clock times if `timsys' is "SCLK";
                      otherwise the times are converted from encoded
                      spacecraft clock to seconds past J2000 TDB.

                      See the Examples section below for a complete example
                      program showing how to retrieve the endpoints from
                      `cover'.
#### Parameters
       None.
#### Exceptions
       1)  If the input file has transfer format, the error
           SPICE(INVALIDFORMAT) is signaled.

       2)  If the input file is not a transfer file but has architecture
           other than DAF, the error SPICE(BADARCHTYPE) is signaled.

       3)  If the input file is a binary DAF file of type other than
           CK, the error SPICE(BADFILETYPE) is signaled.

       4)  If the CK file cannot be opened or read, the error will
           be diagnosed by routines called by this routine. The output
           window will not be modified.

       5)  If the size of the output window argument `cover' is
           insufficient to contain the actual number of intervals in the
           coverage window for `idcode', the error will be diagnosed by
           routines called by this routine.

       6)  If `tol' is negative, the error SPICE(VALUEOUTOFRANGE) is
           signaled.

       7)  If `level' is not recognized, the error SPICE(INVALIDOPTION)
           is signaled.

       8)  If `timsys' is not recognized, the error SPICE(INVALIDOPTION)
           is signaled.

       9)  If a time conversion error occurs, the error will be
           diagnosed by a routine in the call tree of this routine.

       10) If the output time system is TDB, the CK subsystem must be
           able to map `idcode' to the ID code of the associated
           spacecraft clock.  If this mapping cannot be performed, the
           error will be diagnosed by a routine in the call tree of this
           routine.

       11) The error SPICE(EMPTYSTRING) is signaled if any of the input
           strings `ck', `level', or `timsys' do not contain at least one
           character, since such an input string cannot be converted to a
           Fortran-style string in this case.

       12) The error SPICE(NULLPOINTER) is signaled if the if any of the input
           strings `ck', `level', or `timsys' are null.
#### Files
       This routine reads a C-kernel.

       If the output time system is "TDB", then a leapseconds kernel
       and an SCLK kernel for the spacecraft clock associated with
       `idcode' must be loaded before this routine is called.

       If the ID code of the clock associated with `idcode' is not
       equal to

          idcode / 1000

       then the kernel variable

          CK_<idcode>_SCLK

       must be present in the kernel pool to identify the clock
       associated with `idcode'.  This variable must contain the ID code
       to be used for conversion between SCLK and TDB. Normally this
       variable is provided in a text kernel loaded via furnsh_c.
#### Particulars
       This routine provides an API via which applications can determine
       the coverage a specified CK file provides for a specified
       object.
#### Examples
       1)  Display the interval-level coverage for each object in a
           specified CK file. Use tolerance of zero ticks. Do not request
           angular velocity. Express the results in the TDB time system.

           Find the set of objects in the file. Loop over the contents of
           the ID code set:  find the coverage for each item in the set and
           display the coverage.

              #include <stdio.h>
              #include "SpiceUsr.h"

              int main()
              {

                 /.
                 Local parameters
                 ./
                 #define  FILSIZ         256
                 #define  MAXIV          100000
                 #define  WINSIZ         ( 2 * MAXIV )
                 #define  TIMLEN         51
                 #define  MAXOBJ         1000

                 /.
                 Local variables
                 ./
                 SPICEDOUBLE_CELL        ( cover, WINSIZ );
                 SPICEINT_CELL           ( ids,   MAXOBJ );

                 SpiceChar               ck      [ FILSIZ ];
                 SpiceChar               lsk     [ FILSIZ ];
                 SpiceChar               sclk    [ FILSIZ ];
                 SpiceChar               timstr  [ TIMLEN ];

                 SpiceDouble             b;
                 SpiceDouble             e;

                 SpiceInt                i;
                 SpiceInt                j;
                 SpiceInt                niv;
                 SpiceInt                obj;

                 /.
                 Load a leapseconds kernel and SCLK kernel for output time
                 conversion.  Note that we assume a single spacecraft clock is
                 associated with all of the objects in the CK.
                 ./
                 prompt_c ( "Name of leapseconds kernel > ", FILSIZ, lsk );
                 furnsh_c ( lsk );

                 prompt_c ( "Name of SCLK kernel        > ", FILSIZ, sclk );
                 furnsh_c ( sclk );

                 /.
                 Get name of CK file.
                 ./
                 prompt_c ( "Name of CK file            > ", FILSIZ, ck );

                 /.
                 Find the set of objects in the CK file.
                 ./
                 ckobj_c ( ck, &ids );

                 /.
                 We want to display the coverage for each object. Loop over
                 the contents of the ID code set, find the coverage for
                 each item in the set, and display the coverage.
                 ./
                 for ( i = 0;  i < card_c( &ids );  i++  )
                 {
                    /.
                    Find the coverage window for the current object.
                    Empty the coverage window each time so we don't
                    include data for the previous object.
                    ./
                    obj  =  SPICE_CELL_ELEM_I( &ids, i );

                    scard_c ( 0,  &cover );
                    ckcov_c ( ck,          obj,  SPICEFALSE,
                              "INTERVAL",  0.0,  "TDB",       &cover );

                    /.
                    Get the number of intervals in the coverage window.
                    ./
                    niv = wncard_c( &cover );

                    /.
                    Display a simple banner.
                    ./
                    printf ( "%s\n", "========================================" );

                    printf ( "Coverage for object %ld\n", obj );

                    /.
                    Convert the coverage interval start and stop times to TDB
                    calendar strings.
                    ./
                    for ( j = 0;  j < niv;  j++  )
                    {
                       /.
                       Get the endpoints of the jth interval.
                       ./
                       wnfetd_c ( &cover, j, &b, &e );

                       /.
                       Convert the endpoints to TDB calendar
                       format time strings and display them.
                       ./
                       timout_c ( b,
                                  "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                                  TIMLEN,
                                  timstr                                    );

                       printf ( "\n"
                                "Interval:  %ld\n"
                                "Start:     %s\n",
                                j,
                                timstr            );

                       timout_c ( e,
                                  "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                                  TIMLEN,
                                  timstr                                    );
                       printf ( "Stop:      %s\n", timstr );

                    }
                    printf ( "%s\n", "========================================" );

                 }
                 return ( 0 );
              }

       2)  Find the segment-level coverage for the object designated by
           IDCODE provided by the set of CK files loaded via a metakernel.
           (The metakernel must also specify leapseconds and SCLK kernels.)
           Use tolerance of zero ticks. Do not request angular velocity.
           Express the results in the TDB time system.

              #include <stdio.h>
              #include "SpiceUsr.h"

              int main()
              {

                 /.
                 Local parameters
                 ./
                 #define  FILSIZ         256
                 #define  LNSIZE         81
                 #define  MAXCOV         100000
                 #define  WINSIZ         ( 2 * MAXCOV )
                 #define  TIMLEN         51

                 /.
                 Local variables
                 ./
                 SPICEDOUBLE_CELL        ( cover, WINSIZ );

                 SpiceBoolean            found;

                 SpiceChar               file    [ FILSIZ ];
                 SpiceChar               idch    [ LNSIZE ];
                 SpiceChar               meta    [ FILSIZ ];
                 SpiceChar               source  [ FILSIZ ];
                 SpiceChar               timstr  [ TIMLEN ];
                 SpiceChar               type    [ LNSIZE ];

                 SpiceDouble             b;
                 SpiceDouble             e;

                 SpiceInt                count;
                 SpiceInt                handle;
                 SpiceInt                i;
                 SpiceInt                idcode;
                 SpiceInt                niv;

                 /.
                 Prompt for the metakernel name; load the metakernel.
                 The metakernel lists the CK files whose coverage
                 for `idcode' we'd like to determine.  The metakernel
                 must also specify a leapseconds kernel and an SCLK
                 kernel for the clock associated with `idcode'.
                 ./
                 prompt_c ( "Name of metakernel > ", FILSIZ, meta );
                 furnsh_c ( meta );

                 /.
                 Get the ID code of interest.
                 ./
                 prompt_c ( "Enter ID code      > ", LNSIZE, idch );
                 prsint_c ( idch,  &idcode );

                 /.
                 Find out how many kernels are loaded.  Loop over the
                 kernels:  for each loaded CK file, add its coverage
                 for `idcode', if any, to the coverage window.
                 ./
                 ktotal_c ( "CK", &count );

                 for ( i = 0;  i < count;  i++  )
                 {
                    kdata_c  ( i,           "CK",     FILSIZ,
                               LNSIZE,      FILSIZ,   file,
                               type,        source,   &handle,     &found );

                    ckcov_c  ( file,        idcode,   SPICEFALSE,
                               "SEGMENT",   0.0,      "TDB",       &cover );
                 }

                 /.
                 Display results.

                 Get the number of intervals in the coverage window.
                 ./
                 niv = wncard_c( &cover );

                 /.
                 Display a simple banner.
                 ./
                 printf ( "\nCoverage for object %ld\n", idcode );

                 /.
                 Convert the coverage interval start and stop times to TDB
                 calendar strings.
                 ./
                 for ( i = 0;  i < niv;  i++  )
                 {
                    /.
                    Get the endpoints of the ith interval.
                    ./
                    wnfetd_c ( &cover, i, &b, &e );

                    /.
                    Convert the endpoints to TDB calendar
                    format time strings and display them.
                    ./
                    timout_c ( b,
                               "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                               TIMLEN,
                               timstr                                  );

                    printf ( "\n"
                             "Interval:  %ld\n"
                             "Start:     %s\n",
                             i,
                             timstr            );

                    timout_c ( e,
                               "YYYY MON DD HR:MN:SC.###### (TDB) ::TDB",
                               TIMLEN,
                               timstr                                  );
                    printf ( "Stop:      %s\n", timstr );

                 }
                 return ( 0 );
              }
#### Restrictions
       1) When this routine is used to accumulate coverage for `idcode'
          provided by multiple CK files, the inputs `needav', `level', `tol',
          and `timsys'  must have the same values for all files in order
          for the result to be meaningful.
#### Literature_References
       None.
#### Author_and_Institution
       N.J. Bachman   (JPL)
#### Version
       -CSPICE Version 1.0.1, 30-NOV-2007 (NJB)

           Corrected bug in first example program in header:
           program now empties result window prior to collecting
           data for each object. Updated examples to use wncard_c
           rather than card_c. Updated second example to demonstrate
           segment-level summary capability.

       -CSPICE Version 1.0.0, 07-JAN-2005 (NJB)
#### Index_Entries
       get coverage window for ck object
#### Link to routine ckcov_c source file ckcov_c.c

    Thu Apr 16 08:57:28 2009