Table of contents
CSPICE_DSKRB2 determines range bounds for a DSK plate set.
Given:
vrtces an array of coordinates of the vertices.
help, vrtces
DOUBLE = Array[3,NV]
The Ith vertex occupies elements [0:2,I-1] of this array.
plates an array representing the triangular plates of a shape model.
help, plates
LONG = Array[3,NP]
The elements of `plates' are vertex indices; vertex indices are
1-based. The vertex indices of the Ith plate occupy elements
[0:2,I-1] of this array.
corsys an integer parameter identifying the coordinate system in which
the bounds are to be computed.
help, corsys
LONG = Scalar
The bounds apply to the third coordinate in each system:
Latitudinal: radius
Planetodetic: altitude
Rectangular: Z
corpar an array of parameters associated with the coordinate system.
help, corpar
DOUBLE = Array[SPICE_DSK_NSYPAR]
Currently the only supported system that has
associated parameters is the planetodetic system. For
planetodetic coordinates,
corpar[0] is the equatorial radius
corpar[1] is the flattening coefficient. Let `re' and
`rp' represent, respectively, the equatorial and
polar radii of the reference ellipsoid of the
system. Then
corpar[1] = ( re - rp ) / re
the call:
cspice_dskrb2, vrtces, plates, corsys, corpar, mncor3, mxcor3
returns:
mncor3 a lower bound on the range of the third coordinate of the system
identified by `corsys' and `corpar', taken over all plates.
help, mncor3
DOUBLE = Scalar
For latitudinal and rectangular coordinates, `mncor3'
is the greatest lower bound of the third coordinate.
For planetodetic coordinates, `mncor3' is an
approximation: it is less than or equal to the greatest
lower bound.
mxcor3 the least upper bound on the range of the third coordinate of
the system identified by `corsys' and `corpar', taken over all
plates.
help, mxcor3
DOUBLE = Scalar
See the include file IcyDSK.pro for declarations of the public DSK
type 2 parameters used by this routine.
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) Create a three-segment DSK file using plate model data for
Phobos. Use latitudinal, rectangular, and planetodetic
coordinates in the respective segments. This is not a
realistic example, but it serves to demonstrate use of
the supported coordinate systems.
Use the DSK kernel below to provide, for simplicity, the input
plate and vertices data. This file has one segment only.
phobos_3_3.bds
Example code begins here.
PRO dskrb2_ex1
;;
;; IcyUser globally defines DSK parameters.
;; For more information, please see IcyDSK.pro.
;;
@IcyUser
SPICETRUE = 1L
NSEG = 3
cornam = ['radius', 'Z-coordinate', 'Z-coordinate', 'altitude']
;;
;; Assign names of input and output DSK files.
;;
indsk = 'phobos_3_3.bds'
dsk = 'phobos_3_3_3seg.bds'
if ( cspice_exists(dsk) ) then begin
file_delete, dsk
endif
;;
;; Open input DSK for read access; find first segment.
;;
cspice_dasopr, indsk, inhan
cspice_dlabfs, inhan, dladsc, found
;;
;; Fetch vertices and plates from input DSK file.
;;
;; Note that vertex and plate indices are 1-based.
;;
print, 'Reading input data...'
cspice_dskv02, inhan, dladsc, 1, SPICE_DSK02_MAXVRT, vrtces
cspice_dskp02, inhan, dladsc, 1, SPICE_DSK02_MAXPLT, plates
print, 'Done.'
;;
;; Set input array sizes required by cspice_dskmi2.
;;
voxpsz = SPICE_DSK02_MAXVXP
voxlsz = SPICE_DSK02_MXNVLS
worksz = SPICE_DSK02_MAXCEL
spaisz = SPICE_DSK02_SPAISZ
makvtl = SPICETRUE
;;
;; Set fine and coarse voxel scales. (These usually
;; need to determined by experimentation.)
;;
finscl = 5.D
corscl = 4
;;
;; Open a new DSK file.
;;
cspice_dskopn, dsk, dsk, 0, handle
for segno=1, NSEG do begin
;;
;; Create spatial index. We won't generate a
;; vertex-plate mapping, so we set the flag
;; for creating this map to "false."
;;
print, 'Creating segment ', segno
print, 'Creating spatial index...'
cspice_dskmi2, vrtces, plates, finscl, corscl, $
worksz, voxpsz, voxlsz, makvtl, $
spaisz, spaixd, spaixi
print, 'Done.'
;;
;; Set up inputs describing segment attributes:
;;
;; - Central body: Phobos
;; - Surface ID code: user's choice.
;; We use the segment number here.
;; - Data class: general (arbitrary) shape
;; - Body-fixed reference frame
;; - Time coverage bounds (TBD)
;;
center = 401
surfid = segno
dclass = SPICE_DSK_GENCLS
frame = 'IAU_PHOBOS'
first = -50.D * cspice_jyear()
last = 50.D * cspice_jyear()
;;
;; Set the coordinate system and coordinate system
;; bounds based on the segment index.
;;
;; Zero out the coordinate parameters to start.
;;
corpar = dblarr(SPICE_DSK_NSYPAR)
case segno of
1 : begin
;;
;; Use planetocentric latitudinal coordinates. Set
;; the longitude and latitude bounds.
;;
corsys = SPICE_DSK_LATSYS
mncor1 = -cspice_pi()
mxcor1 = cspice_pi()
mncor2 = -cspice_halfpi()
mxcor2 = cspice_halfpi()
end
2 : begin
;;
;; Use rectangular coordinates. Set the
;; X and Y bounds.
;;
;; The bounds shown here were derived from
;; the plate data. They lie slightly outside
;; of the range spanned by the plates.
;;
corsys = SPICE_DSK_RECSYS
mncor1 = -1.3D
mxcor1 = 1.31D
mncor2 = -1.21D
mxcor2 = 1.2D
end
3 : begin
;;
;; Set the coordinate system to planetodetic.
;;
corsys = SPICE_DSK_PDTSYS
mncor1 = -cspice_pi()
mxcor1 = cspice_pi()
mncor2 = -cspice_halfpi()
mxcor2 = cspice_halfpi()
;;
;; We'll use equatorial and polar radii from
;; pck00010.tpc. These normally would be fetched
;; at run time, but for simplicity, we'll use
;; hard-coded values.
;;
re = 13.D0
rp = 9.1D
f = ( re - rp ) / re
corpar = [ re, f ]
end
else: message, 'Icy(BUG)'
endcase
;;
;; Compute plate model radius bounds.
;;
print, 'Computing ' + cornam[corsys-1] +' bounds of plate set...'
cspice_dskrb2, vrtces, plates, corsys, corpar, mncor3, mxcor3
print, 'Done.'
;;
;; Write the segment to the file.
;;
print, 'Writing segment...'
cspice_dskw02, handle, $
center, $
surfid, $
dclass, $
frame, $
corsys, $
corpar, $
mncor1, $
mxcor1, $
mncor2, $
mxcor2, $
mncor3, $
mxcor3, $
first, $
last, $
vrtces, $
plates, $
spaixd, $
spaixi
end
;;
;; Close the input DSK.
;;
cspice_dskcls, handle, SPICETRUE
cspice_dascls, inhan
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, the output was:
Reading input data...
Done.
Creating segment 1
Creating spatial index...
Done.
Computing radius bounds of plate set...
Done.
Writing segment...
Creating segment 2
Creating spatial index...
Done.
Computing Z-coordinate bounds of plate set...
Done.
Writing segment...
Creating segment 3
Creating spatial index...
Done.
Computing altitude bounds of plate set...
Done.
Writing segment...
Note that after run completion, a new DSK exists in the output
directory.
Users planning to create DSK files should consider whether the
SPICE DSK creation utility MKDSK may be suitable for their needs.
This routine supports use of the DSK type 2 segment writer cspice_dskw02
by computing bounds on the range of the third coordinates of
the input plate set.
1) If the input coordinate system is not recognized, the error
SPICE(NOTSUPPORTED) is signaled by a routine in the call tree
of this routine.
2) If a conversion from rectangular to planetodetic coordinates
fails, an error is signaled by a routine in the call
tree of this routine.
3) If any of the input arguments, `vrtces', `plates', `corsys' or
`corpar', is undefined, an error is signaled by the IDL error
handling system.
4) If any of the input arguments, `vrtces', `plates', `corsys' or
`corpar', is not of the expected type, or it does not have the
expected dimensions and size, an error is signaled by the Icy
interface.
5) If any of the output arguments, `mncor3' or `mxcor3', is not a
named variable, an error is signaled by the Icy interface.
None.
1) For planetodetic coordinates, the computation of the lower
altitude bound requires that the surface at altitude `mncor3' be
convex. This is the case for realistic geometries, but can
be false if a plate is very large compared to the overall
shape model.
ICY.REQ
DAS.REQ
DSK.REQ
None.
J. Diaz del Rio (ODC Space)
M. Liukis (JPL)
E.D. Wright (JPL)
-Icy Version 1.0.1, 27-AUG-2021 (JDR)
Edited the header to comply with NAIF standard.
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, 14-DEC-2016 (ML) (EDW)
compute range bounds for type 2 DSK segment
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