void ckcov_c ( ConstSpiceChar * ck,
SpiceInt idcode,
SpiceBoolean needav,
ConstSpiceChar * level,
SpiceDouble tol,
ConstSpiceChar * timsys,
SpiceCell * cover )
Find the coverage window for a specified object in a specified CK
file.
CELLS
DAF
CK
TIME
WINDOWS
POINTING
TIME
UTILITY
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'.
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.
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'.
None.
This routine provides an API via which applications can determine
the coverage a specified CK file provides for a specified
object.
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 );
}
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.
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 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.
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.
N.J. Bachman (JPL)
None.
-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)
get coverage window for ck object
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