| dskn02 |
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Table of contents
Procedure
DSKN02 ( DSK, type 2, compute normal vector for plate )
SUBROUTINE DSKN02 ( HANDLE, DLADSC, PLID, NORMAL )
Abstract
Compute the unit normal vector for a specified plate from a type
2 DSK segment.
Required_Reading
DAS
DSK
Keywords
DAS
DSK
FILES
Declarations
IMPLICIT NONE
INCLUDE 'dla.inc'
INCLUDE 'dskdsc.inc'
INCLUDE 'dsk02.inc'
INTEGER HANDLE
INTEGER DLADSC ( * )
INTEGER PLID
DOUBLE PRECISION NORMAL ( 3 )
Brief_I/O
VARIABLE I/O DESCRIPTION
-------- --- --------------------------------------------------
HANDLE I DSK file handle.
DLADSC I DLA descriptor.
PLID I Plate ID.
NORMAL O Plate's unit normal vector.
Detailed_Input
HANDLE is the handle of a DSK file containing a type 2
segment from which data are to be fetched.
DLADSC is the DLA descriptor associated with the segment
from which data are to be fetched.
PLID is the plate ID. Plate IDs range from 1 to NP
(the number of plates).
Detailed_Output
NORMAL is the normal vector associated with the plate
designated by PLID. The direction of NORMAL is
determined by the order of the plate's vertices;
the vertices are presumed to be ordered in the
right-handed (counterclockwise) sense about the
normal direction. If the plate's vertices are
V1, V2, V3, then NORMAL points in the direction
(V2 - V1) x ( V3 - V2 )
where "x" represents the cross product operator.
The vector NORMAL is expressed in the body-fixed
reference frame of the segment designated by DLADSC.
The center of this frame is the origin of the cartesian
coordinate system in which the vertices are expressed.
Note that the frame center need not coincide with the
central body of the segment. Units are km.
The vector has magnitude 1.
If an error occurs on the call, NORMAL is undefined.
Parameters
See the include file
dla.inc
for declarations of DLA descriptor sizes and documentation of the
contents of DLA descriptors.
See the include file
dskdsc.inc
for declarations of DSK descriptor sizes and documentation of the
contents of DSK descriptors.
See the include file
dsk02.inc
for declarations of DSK data type 2 (plate model) parameters.
Exceptions
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 PLID is less than 1 or greater than the number of plates
in the segment, the error SPICE(INDEXOUTOFRANGE) is signaled.
5) This routine does not check for linear independence of the
plate's edges. The plate model is assumed to be geometrically
valid.
Files
See input argument HANDLE.
Particulars
None.
Examples
The numerical results shown for this example 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) Look up all the vertices associated with each plate
of the model contained in a specified type 2 segment. For each
of the first 5 plates, display the plate's vertices and normal
vector.
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.
PROGRAM DSKN02_EX1
IMPLICIT NONE
INCLUDE 'dla.inc'
INCLUDE 'dsk02.inc'
CHARACTER*(*) FMT
PARAMETER ( FMT = '(1X,A,3(1XE15.8))' )
INTEGER BUFSIZ
PARAMETER ( BUFSIZ = 10000 )
INTEGER FILSIZ
PARAMETER ( FILSIZ = 255 )
CHARACTER*(FILSIZ) DSK
DOUBLE PRECISION NORMAL ( 3 )
DOUBLE PRECISION VERTS ( 3, BUFSIZ )
INTEGER DLADSC ( DLADSZ )
INTEGER HANDLE
INTEGER I
INTEGER J
INTEGER N
INTEGER NNORM
INTEGER NP
INTEGER NREAD
INTEGER NV
INTEGER NVTX
INTEGER PLATES ( 3, BUFSIZ )
INTEGER PLIX
INTEGER REMAIN
INTEGER START
LOGICAL FOUND
C
C Prompt for name of DSK and open file for reading.
C
CALL PROMPT ( 'Enter DSK name > ', DSK )
CALL DASOPR ( DSK, HANDLE )
CALL DLABFS ( HANDLE, DLADSC, FOUND )
IF ( .NOT. FOUND ) THEN
CALL SETMSG ( 'No segment found in file #.' )
CALL ERRCH ( '#', DSK )
CALL SIGERR ( 'SPICE(NOSEGMENT)' )
END IF
C
C Get segment vertex and plate counts.
C
CALL DSKZ02 ( HANDLE, DLADSC, NV, NP )
WRITE (*,*) ' '
WRITE (*,*) 'Number of vertices: ', NV
WRITE (*,*) 'Number of plates: ', NP
C
C Display the vertices of the first 5 plates.
C
REMAIN = MIN(5, NP)
START = 1
DO WHILE ( REMAIN .GT. 0 )
C
C NREAD is the number of plates we'll read on this
C loop pass.
C
NREAD = MIN ( BUFSIZ, REMAIN )
CALL DSKP02 ( HANDLE, DLADSC, START, NREAD, N,
. PLATES )
DO I = 1, N
PLIX = START + I - 1
C
C Read the vertices of the current plate.
C
DO J = 1, 3
CALL DSKV02 ( HANDLE, DLADSC, PLATES(J,I),
. 1, NVTX, VERTS (1,J) )
END DO
C
C Display the vertices of the current plate:
C
WRITE (*,* ) ' '
WRITE (*,* ) 'Plate number: ', PLIX
WRITE (*,FMT) ' Vertex 1: ', (VERTS(J,1), J=1,3)
WRITE (*,FMT) ' Vertex 2: ', (VERTS(J,2), J=1,3)
WRITE (*,FMT) ' Vertex 3: ', (VERTS(J,3), J=1,3)
C
C Display the normal vector of the current plate:
C
CALL DSKN02 ( HANDLE, DLADSC, PLIX, NORMAL )
WRITE (*,FMT) ' Normal: ', (NORMAL(J), J=1,3)
END DO
START = START + NREAD
REMAIN = REMAIN - NREAD
END DO
C
C Close the kernel. This isn't necessary in a stand-
C alone program, but it's good practice in subroutines
C because it frees program and system resources.
C
CALL DASCLS ( HANDLE )
END
When this program was executed on a Mac/Intel/gfortran/64-bit
platform, using the DSK file named phobos512.bds, the output
was:
Enter DSK name > phobos512.bds
Number of vertices: 1579014
Number of plates: 3145728
Plate number: 1
Vertex 1: -0.67744400E+01 0.62681500E+01 0.60114900E+01
Vertex 2: -0.67623800E+01 0.62572800E+01 0.60255600E+01
Vertex 3: -0.67571000E+01 0.62775400E+01 0.60209600E+01
Normal: -0.58197377E+00 0.32128561E+00 0.74704892E+00
Plate number: 2
Vertex 1: -0.67744400E+01 0.62681500E+01 0.60114900E+01
Vertex 2: -0.67797300E+01 0.62479000E+01 0.60161000E+01
Vertex 3: -0.67623800E+01 0.62572800E+01 0.60255600E+01
Normal: -0.58145695E+00 0.32198831E+00 0.74714881E+00
Plate number: 3
Vertex 1: -0.67797300E+01 0.62479000E+01 0.60161000E+01
Vertex 2: -0.67676800E+01 0.62370100E+01 0.60301900E+01
Vertex 3: -0.67623800E+01 0.62572800E+01 0.60255600E+01
Normal: -0.58159707E+00 0.32264196E+00 0.74675767E+00
Plate number: 4
Vertex 1: -0.67797300E+01 0.62479000E+01 0.60161000E+01
Vertex 2: -0.67849900E+01 0.62276200E+01 0.60207000E+01
Vertex 3: -0.67676800E+01 0.62370100E+01 0.60301900E+01
Normal: -0.58312901E+00 0.32056070E+00 0.74645924E+00
Plate number: 5
Vertex 1: -0.67849900E+01 0.62276200E+01 0.60207000E+01
Vertex 2: -0.67729900E+01 0.62167400E+01 0.60348200E+01
Vertex 3: -0.67676800E+01 0.62370100E+01 0.60301900E+01
Normal: -0.58366405E+00 0.32306020E+00 0.74496200E+00
Note that only the vertex information for first 5 plates is
provided.
Restrictions
See $Exceptions section.
Literature_References
None.
Author_and_Institution
N.J. Bachman (JPL)
J. Diaz del Rio (ODC Space)
B.V. Semenov (JPL)
Version
SPICELIB Version 1.0.1, 09-JUL-2020 (JDR) (BVS)
Edited the header to comply with NAIF standard. Modified code
example to reduce the output.
Extended detailed description of NORMAL output argument and
added an additional record to $Index_Entries.
SPICELIB Version 1.0.0, 17-MAR-2016 (NJB)
Now calls ZZDDHHLU.
Deleted references to unused parameter. Updated
$Examples section.
DSKLIB Version 1.0.0, 02-JUN-2010 (NJB)
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Fri Dec 31 18:36:15 2021