Table of contents
CSPICE_DSKD02 fetches double precision data from a type 2 DSK segment.
Given:
handle the handle of a DSK file containing a type 2 segment from which
data are to be fetched.
help, handle
LONG = Scalar
dladsc the DLA descriptor associated with the segment from which data
are to be fetched.
help, dladsc
LONG = Array[SPICE_DLA_DSCSIZ]
item an integer "keyword" parameter designating the double precision
data item to fetch.
help, item
LONG = Scalar
Names, values, and meanings of keyword parameters
supported by this routine are shown below.
Use of the names shown here is enabled by calling
the DSK Icy parameter definition routine as shown:
@IcyUser
This call must be made before the parameter names
are referenced. See the example program below.
Name Value Description
---- ----- ----------
SPICE_DSK02_KWDSC 15 Array containing contents of Fortran
DSK descriptor of segment. Note
that DSK descriptors are not to be
confused with DLA descriptors, which
contain segment component base
address and size information. The
dimension of this array is
SPICE_DSK_DSCSIZ.
SPICE_DSK02_KWVTBD 16 Vertex bounds. This is an array of
six values giving the minimum and
maximum values of each component
of the vertex set.
SPICE_DSK02_KWVXOR 17 Voxel grid origin. This is the
location of the voxel grid origin in
the body-fixed frame associated with
the target body.
SPICE_DSK02_KWVXSZ 18 Voxel size. DSK voxels are cubes;
the edge length of each cube is
given by the voxel size. This size
applies to the fine voxel grid. Units
are km.
SPICE_DSK02_KWVERT 19 Vertex coordinates.
start the start index within the specified data item from which data
are to be fetched.
help, start
LONG = Scalar
The index of the first element of each data item is 0. This
convention applies uniformly to all data, even if the data are
associated with a set of 1-based indices. For example, the
vertex ID range starts at 1 (this fact is language-independent),
but a caller would use a `start' value of 0 to fetch the first
vertex.
room the amount of room in the output array.
help, room
LONG = Scalar
It is permissible to provide an output array that has too
little room to fetch an item in one call.
the call:
cspice_dskd02, handle, dladsc, item, start, room, values
returns:
values a contiguous set of elements of the item designated by `item'.
help, values
DOUBLE = Array[N]
The correspondence of `values' with the elements
of the data item is:
values[0] item[start]
... ...
values[n-1] item[start+n-1]
If an error occurs on the call, `values' is undefined.
Note, room >= n.
See the parameter definitions file
IcyDLA.pro
for declarations of DLA descriptor sizes and documentation of the
contents of DLA descriptors.
See the parameter definitions file
IcyDSK.pro
for declarations of DSK descriptor sizes and documentation of the
contents of DSK descriptors.
See the parameter definitions file
IcyDSK.pro
for declarations of DSK data type 2 (plate model) parameters.
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.
1) Look up all the vertices associated with each plate
of the model contained in a specified type 2 segment.
For the first 5 plates, display the plate's vertices.
For this example, we'll show the context of this look-up:
opening the DSK file for read access, traversing a trivial,
one-segment list to obtain the segment of interest.
Example code begins here.
PRO dskd02_ex1
;;
;; IcyUser globally defines DSK parameters.
;; For more information, please see IcyDSK.pro
;;
@IcyUser
;;
;; Local constants
;;
FMT = '(A,3(1X,E14.6))'
;;
;; Local variables
;;
dsk = ''
;;
;; Set the dimensions of the array `vrtces', which
;; will be used later.
;;
vrtces = dindgen(3, 3) * 0.D
;;
;; Prompt for the name of the file to search.
;;
read, dsk, PROMPT='Enter name of DSK file > '
;;
;; Open the DSK file for read access.
;; We use the DAS-level interface for
;; this function.
;;
cspice_dasopr, dsk, handle
;;
;; Begin a forward search through the
;; kernel, treating the file as a DLA.
;; In this example, it's a very short
;; search.
;;
cspice_dlabfs, handle, dladsc, found
if ( ~found ) then begin
;;
;; We arrive here only if the kernel
;; contains no segments. This is
;; unexpected, but we're prepared for it.
;;
message, 'No segments found in DSK file ', + dsk
return
endif
;;
;; If we made it this far, `dladsc' is the
;; DLA descriptor of the first segment.
;;
;;
;; Find the number of plates in the model.
;;
cspice_dski02, handle, dladsc, SPICE_DSK02_KWNP, 0, 1, ival
print, 'Number of plates: ', ival[0]
;;
;; For the first 5 plates, look up the desired data.
;; Note that plate numbers range from 1 to np.
;;
np = min([ival[0], 5])
for i=1, np do begin
;;
;; For the Ith plate, find the associated
;; vertex IDs. We must take into account
;; the fact that each plate has three
;; vertices when we compute the start
;; index.
;;
start = 3*(i-1);
;;
;; Fetch the ith plate.
;;
cspice_dski02, handle, dladsc, SPICE_DSK02_KWPLAT, $
start, 3, vrtids
for j = 0, 2 do begin
;;
;; Fetch the jth vertex of the ith plate.
;;
start = (vrtids[j]-1) * 3;
cspice_dskd02, handle, dladsc, SPICE_DSK02_KWVERT, $
start, 3 , vtemp
vrtces[j,*] = vtemp
endfor
;;
;; Display the vertices of the ith plate:
;;
print
print, 'Plate number: ', i
print, format=FMT, 'Vertex 1: ', vrtces[0,*]
print, format=FMT, 'Vertex 2: ', vrtces[1,*]
print, format=FMT, 'Vertex 3: ', vrtces[2,*]
endfor
;;
;; Close the DSK.
;;
cspice_dascls, handle
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, using the DSK file named phobos512.bds, the output
was:
Enter name of DSK file > phobos512.bds
Number of plates: 3145728
Plate number: 1
Vertex 1: -6.774440E+00 6.268150E+00 6.011490E+00
Vertex 2: -6.762380E+00 6.257280E+00 6.025560E+00
Vertex 3: -6.757100E+00 6.277540E+00 6.020960E+00
Plate number: 2
Vertex 1: -6.774440E+00 6.268150E+00 6.011490E+00
Vertex 2: -6.779730E+00 6.247900E+00 6.016100E+00
Vertex 3: -6.762380E+00 6.257280E+00 6.025560E+00
Plate number: 3
Vertex 1: -6.779730E+00 6.247900E+00 6.016100E+00
Vertex 2: -6.767680E+00 6.237010E+00 6.030190E+00
Vertex 3: -6.762380E+00 6.257280E+00 6.025560E+00
Plate number: 4
Vertex 1: -6.779730E+00 6.247900E+00 6.016100E+00
Vertex 2: -6.784990E+00 6.227620E+00 6.020700E+00
Vertex 3: -6.767680E+00 6.237010E+00 6.030190E+00
Plate number: 5
Vertex 1: -6.784990E+00 6.227620E+00 6.020700E+00
Vertex 2: -6.772990E+00 6.216740E+00 6.034820E+00
Vertex 3: -6.767680E+00 6.237010E+00 6.030190E+00
Most user applications will not need to call this routine. The
routines
cspice_dskz02
cspice_dskp02
cspice_dskv02
have simpler interfaces and may be used to fetch the plates
and vertex counts, and the plates and vertices themselves,
from a type DSK segment. See the documentation of those
routines for code examples.
DSK files are built using the DLA low-level format and
the DAS architecture; DLA files are a specialized type of DAS
file in which data are organized as a doubly linked list of
segments. Each segment's data belong to contiguous components of
character, double precision, and integer type.
Note that the DSK descriptor for the segment is not needed by this
routine; the DLA descriptor contains the base address and size
information for the integer, double precision, and character
components of the segment, and these suffice for the purpose of
fetching data.
1) If the input handle is invalid, an error is signaled by a
routine in the call tree of this routine.
2) If a file read error occurs, the error is signaled by a
routine in the call tree of this routine.
3) If the input DLA descriptor is invalid, the effect of this
routine is undefined. The error *may* be diagnosed by
routines in the call tree of this routine, but there are no
guarantees.
4) If `room' is non-positive, the error SPICE(VALUEOUTOFRANGE)
is signaled by a routine in the call tree of this routine.
5) If the coarse voxel scale read from the designated segment is
less than 1, the error SPICE(VALUEOUTOFRANGE) is signaled by a
routine in the call tree of this routine.
6) If the input keyword parameter is not recognized, the error
SPICE(NOTSUPPORTED) is signaled by a routine in the call tree
of this routine.
7) If `start' is less than 1 or greater than the size of the
item to be fetched, the error SPICE(INDEXOUTOFRANGE) is
signaled by a routine in the call tree of this routine.
8) If any of the input arguments, `handle', `dladsc', `item',
`start' or `room', is undefined, an error is signaled by the
IDL error handling system.
9) If any of the input arguments, `handle', `dladsc', `item',
`start' or `room', is not of the expected type, or it does not
have the expected dimensions and size, an error is signaled by
the Icy interface.
10) If the output argument `values' is not a named variable, an
error is signaled by the Icy interface.
See input argument `handle'.
1) This routine uses discovery check-in to boost
execution speed. However, this routine is in
violation of NAIF standards for use of discovery
check-in: routines called from this routine may
signal errors. If errors are signaled in called
routines, this routine's name will be missing
from the traceback message.
DAS.REQ
DSK.REQ
ICY.REQ
None.
J. Diaz del Rio (ODC Space)
M. Liukis (JPL)
E.D. Wright (JPL)
-Icy Version 1.0.1, 31-MAY-2021 (JDR)
Edited the header to comply with NAIF standard. Updated
code example to prompt for the input DSK file and reduce the
number of plates whose vertices are shown on output.
Added -Parameters, -Exceptions, -Files, -Restrictions,
-Literature_References and -Author_and_Institution sections.
Removed reference to the routine's corresponding CSPICE header from
-Abstract section.
Added arguments' type and size information in the -I/O section.
-Icy Version 1.0.0, 04-APR-2017 (ML) (EDW)
fetch double precision data from a type 2 DSK segment
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