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Index Page ckcov_c

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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

       ckcov_c ( CK coverage )

       void ckcov_c ( ConstSpiceChar    * ckfnm,
                      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
       --------  ---  --------------------------------------------------
       ckfnm      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

       ckfnm       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 SPICE 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 `ckfnm'.

                   If `cover' contains no data on input, its size and
                   cardinality still must be initialized.

                   `cover' must be declared as a double precision SpiceCell.

                   CSPICE provides the following macro, which declares and
                   initializes the cell

                      SPICEDOUBLE_CELL        ( cover, COVERSZ );

                   where COVERSZ is the maximum capacity of `cover'.

#### Detailed_Output

       cover       is a SPICE 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 `ckfnm', 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 by a routine in the call tree
           of this routine.

       2)  If the input file is not a transfer file but has architecture
           other than DAF, the error SPICE(INVALIDARCHTYPE) is signaled
           by a routine in the call tree of this routine.

       3)  If the input file is a binary DAF file of type other than CK,
           the error SPICE(INVALIDFILETYPE) is signaled by a routine in
           the call tree of this routine.

       4)  If the CK file cannot be opened or read, an error is signaled
           by a routine in the call tree of 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', an error is signaled by a routine
           in the call tree of this routine.

       6)  If `tol' is negative, the error SPICE(VALUEOUTOFRANGE) is
           signaled by a routine in the call tree of this routine.

       7)  If `level' is not recognized, the error SPICE(INVALIDOPTION)
           is signaled by a routine in the call tree of this routine.

       8)  If `timsys' is not recognized, the error SPICE(NOTSUPPORTED)
           is signaled by a routine in the call tree of this routine.

       9)  If a time conversion error occurs, the error is signaled 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, an error is
           signaled by a routine in the call tree of this routine.

       11) If the input CK type is not one of the supported CK types, the
           error SPICE(NOTSUPPORTED) is signaled by a routine in the call
           tree of this routine. This problem may indicate the version of
           the SPICE Toolkit being used is outdated and a new version is
           required.

       12) If any of the `ckfnm', `level' or `timsys' input string
           pointers is null, the error SPICE(NULLPOINTER) is signaled.

       13) If any of the `ckfnm', `level' or `timsys' input strings has
           zero length, the error SPICE(EMPTYSTRING) is signaled.

       14) If the `cover' cell argument has a type other than
           SpiceDouble, the error SPICE(TYPEMISMATCH) is signaled.

#### 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

       The numerical results shown for these examples may differ across
       platforms. The results depend on the SPICE kernels used as
       input, the compiler and supporting libraries, and the machine
       specific arithmetic implementation.

       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.

          Example code begins here.

          /.
             Program ckcov_ex1
          ./
          #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               ckfnm   [ 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, ckfnm );

             /.
             Find the set of objects in the CK file.
             ./
             ckobj_c ( ckfnm, &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 ( ckfnm,       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 %d\n", (int)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:  %d\n"
                            "Start:     %s\n",
                            (int)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 );
          }

          When this program was executed on a Mac/Intel/cc/64-bit
          platform, using the LSK file named naif0010.tls, the SCLK file
          named cas00145.tsc and the CK file named 08052_08057ra.bc, the
          output was:

          Name of leapseconds kernel > naif0010.tls
          Name of SCLK kernel        > cas00145.tsc
          Name of CK file            > 08052_08057ra.bc
          ========================================
          Coverage for object -82000

          Interval:  0
          Start:     2008 FEB 21 00:01:07.771186 (TDB)
          Stop:      2008 FEB 23 22:53:30.001738 (TDB)

          Interval:  1
          Start:     2008 FEB 23 22:58:13.999732 (TDB)
          Stop:      2008 FEB 24 02:22:25.913175 (TDB)

          Interval:  2
          Start:     2008 FEB 24 02:27:49.910886 (TDB)
          Stop:      2008 FEB 24 19:46:33.470587 (TDB)

          Interval:  3
          Start:     2008 FEB 24 19:49:33.469315 (TDB)
          Stop:      2008 FEB 25 04:25:21.250677 (TDB)

          Interval:  4
          Start:     2008 FEB 25 04:29:33.248897 (TDB)
          Stop:      2008 FEB 25 15:23:44.971594 (TDB)

          Interval:  5
          Start:     2008 FEB 25 15:24:12.971396 (TDB)
          Stop:      2008 FEB 25 20:25:04.843864 (TDB)

          Interval:  6
          Start:     2008 FEB 25 20:25:48.843553 (TDB)
          Stop:      2008 FEB 26 00:01:04.752306 (TDB)
          ========================================

       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.

          Use the meta-kernel shown below to load the required SPICE
          kernels.

             KPL/MK

             File name: ckcov_ex2.tm

             This meta-kernel is intended to support operation of SPICE
             example programs. The kernels shown here should not be
             assumed to contain adequate or correct versions of data
             required by SPICE-based user applications.

             In order for an application to use this meta-kernel, the
             kernels referenced here must be present in the user's
             current working directory.

             The names and contents of the kernels referenced
             by this meta-kernel are as follows:

               File name                      Contents
               ---------                      --------
               naif0010.tls                   Leapseconds
               cas00145.tsc                   Cassini SCLK
               08052_08057ra.bc               Orientation for Cassini

             \begindata

               KERNELS_TO_LOAD = ( 'naif0010.tls'
                                   'cas00145.tsc'
                                   '08052_08057ra.bc')

             \begintext

             End of meta-kernel

          Example code begins here.

          /.
             Program ckcov_ex2
          ./
          #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 %d\n", (int)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:  %d\n"
                         "Start:     %s\n",
                         (int)i,
                         timstr            );

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

             }
             return ( 0 );
          }

          When this program was executed on a Mac/Intel/cc/64-bit
          platform, using the meta-kernel file named ckcov_ex2.tm and
          the NAIF ID "-82000" (Cassini spacecraft bus), the output was:

          Name of metakernel > ckcov_ex2.tm
          Enter ID code      > -82000

          Coverage for object -82000

          Interval:  0
          Start:     2008 FEB 21 00:01:07.771186 (TDB)
          Stop:      2008 FEB 26 00:01:04.752306 (TDB)

#### 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)
       J. Diaz del Rio     (ODC Space)
       E.D. Wright         (JPL)

#### Version

       -CSPICE Version 1.0.4, 25-AUG-2021 (JDR)

           Changed input argument name "ck" to "ckfnm" for consistency
           with other routines.

           Edited the header to comply with NAIF standard. Added solutions using
           CASSINI data.

           Extended description of argument "cover" in -Detailed_Input to include
           type and preferred declaration method.

           Added entry #11 and updated entry #2, #3 and #8's short error message in
           -Exceptions section.

       -CSPICE Version 1.0.3, 12-JUL-2016 (EDW)

           Edit to example program to use "%d" with explicit casts
           to int for printing SpiceInts with printf.

       -CSPICE Version 1.0.2, 01-JUL-2014 (NJB)

           Updated index entries.

       -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
       get coverage start and stop time for ck_object
       get coverage start and stop time for CK frame
       get coverage start and stop time for CK instrument

#### Link to routine ckcov_c source file ckcov_c.c

    Fri Dec 31 18:41:02 2021