Table of contents
CSPICE_DSKRB2 determines range bounds for a DSK plate set.
Given:
vrtces an array of coordinates of the vertices.
[3,m] = size(vrtces); double = class(vrtces)
The Ith vertex occupies elements [1:3,I] of this array.
plates an array representing the triangular plates of a
shape model.
[3,n] = size(plates); int32 = class(plates)
The elements of `plates' are vertex indices; vertex indices
are 1-based. The vertex indices of the Ith plate occupy
elements [1:3,I] of this array.
corsys an integer parameter identifying the coordinate
system in which the bounds are to be computed.
[1,1] = size(corsys); int32 = class(corsys)
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.
[2,1] = size(corpar); double = class(corpar)
Currently the only supported system that has
associated parameters is the planetodetic system. For
planetodetic coordinates,
corpar(1) is the equatorial radius
corpar(2) is the flattening coefficient. Let `re' and
`rp' represent, respectively, the equatorial and
polar radii of the reference ellipsoid of the
system. Then
corpar(2) = ( re - rp ) / re
the call:
[mncor3, mxcor3] = cspice_dskrb2( vrtces, plates, corsys, corpar )
returns:
mncor3 a lower bound on the range of the third coordinate
of the system identified by `corsys' and `corpar', taken
over all plates.
[1,1] = size(mncor3); double = class(mncor3)
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.
[1,1] = size(mxcor3); double = class(mxcor3)
See the include file MiceDSK.m 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 vertex data. This file has one segment only.
phobos_3_3.bds
Example code begins here.
function dskrb2_ex1()
%
% MiceUser globally defines DSK parameters.
% For more information, please see MiceDSK.m.
%
MiceUser
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 ( exist( dsk, 'file' ) == 2 )
delete( dsk )
end
%
% Open input DSK for read access; find first segment.
%
inhan = cspice_dasopr( indsk );
[dladsc, found] = cspice_dlabfs( inhan );
%
% Fetch vertices and plates from input DSK file.
%
% Note that vertex and plate indices are 1-based.
%
disp( 'Reading input data...' )
vrtces = cspice_dskv02( inhan, dladsc, 1, SPICE_DSK02_MAXVRT );
plates = cspice_dskp02( inhan, dladsc, 1, SPICE_DSK02_MAXPLT );
disp( '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 = true;
%
% Set fine and coarse voxel scales. (These usually
% need to determined by experimentation.)
%
finscl = 5.0;
corscl = 4;
%
% Open a new DSK file.
%
handle = cspice_dskopn( dsk, dsk, 0 );
for segno=1:NSEG
%
% Create spatial index. We won't generate a
% vertex-plate mapping, so we set the flag
% for creating this map to "false."
%
fprintf( 'Creating segment %d\n', segno )
fprintf( 'Creating spatial index...\n' )
[spaixd, spaixi] = cspice_dskmi2( vrtces, plates, finscl, ...
corscl, worksz, voxpsz, ...
voxlsz, makvtl, spaisz );
fprintf( 'Done.\n')
%
% 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. * cspice_jyear();
last = 50. * cspice_jyear();
%
% Set the coordinate system and coordinate system
% bounds based on the segment index.
%
% Zero out the coordinate parameters to start.
%
corpar = zeros(SPICE_DSK_NSYPAR,1);
switch segno
case 1
%
% 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();
case 2
%
% 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 = -1.3;
mxcor1 = 1.31;
mncor2 = -1.21;
mxcor2 = 1.2;
case 3
%
% 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 = 13.0;
rp = 9.1;
f = ( re - rp ) / re;
corpar = [ re, f ]';
otherwise
error( 'Mice(BUG)' )
end
%
% Compute plate model radius bounds.
%
fprintf( 'Computing %s bounds of plate set...\n', ...
char(cornam(corsys)) )
[mncor3, mxcor3] = cspice_dskrb2( vrtces, plates, ...
corsys, corpar );
fprintf ( 'Done.\n' )
%
% Write the segment to the file.
%
fprintf( 'Writing segment...\n' )
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_dascls( inhan )
cspice_dskcls( handle, true )
When this program was executed on a Mac/Intel/Octave6.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 Matlab
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 Mice
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.
MICE.REQ
DAS.REQ
DSK.REQ
None.
N.J. Bachman (JPL)
J. Diaz del Rio (ODC Space)
E.D. Wright (JPL)
-Mice Version 1.1.0, 27-AUG-2021 (EDW) (JDR)
Edited the header to comply with NAIF standard.
Added -Parameters, -Exceptions, -Files, -Restrictions,
-Literature_References and -Author_and_Institution sections, and
completed -Particulars section.
Added proper usage string. Added missing information
to -I/O descriptions.
Eliminated use of "lasterror" in rethrow.
Removed reference to the function's corresponding CSPICE header from
-Required_Reading section.
-Mice Version 1.0.0, 04-FEB-2016 (EDW) (NJB)
compute range bounds for type 2 DSK segment
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