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Required Reading


   CSPICE_DSKRB2 determine range bounds for a DSK plate set.

   For important details concerning this module's function, please refer to
   the CSPICE routine dskrb2_c.



      vrtces      is an array of coordinates of the vertices. The Ith
                  vertex occupies elements [0:2,I-1] of this array.

      plates      is an array representing the triangular plates of a
                  shape model. 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      is an integer parameter identifying the coordinate
                  system in which the bounds are to be computed.

                  The bounds apply to the third coordinate in each system:

                     Latitudinal:           radius
                     Planetodetic:          altitude
                     Rectangular:           Z

      corpar     is a array of parameters associated with the coordinate

                 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


      mncor3    is a lower bound on the range of the third coordinate
                of the system identified by `corsys' and `corpar', taken
                over all plates.

                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    is the least upper bound on the range of the third
                coordinate of the system identified by `corsys' and
                `corpar', taken over all plates.


   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.

   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.

   For simplicity, use an existing DSK file to provide the
   input plate and vertex data. The selected input file has one

      PRO DSKW02_T

         ;; IcyUser globally defines DSK parameters.
         ;; For more information, please see DSKIcyUser.m and
         ;; DSKIcyUser02.m.

         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

         ;; 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()


               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


               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 ]


               else: message, 'Icy(BUG)'


           ;; 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, $


         ;; Close the input DSK.
         cspice_dskcls, handle, SPICETRUE
         cspice_dascls, inhan


   IDL outputs:

      Reading input data...
      Creating segment        1
      Creating spatial index...
      Computing radius bounds of plate set...
      Writing segment...
      Creating segment        2
      Creating spatial index...
      Computing Z-coordinate bounds of plate set...
      Writing segment...
      Creating segment        3
      Creating spatial index...
      Computing altitude bounds of plate set...
      Writing segment...

      After run completion, A 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.

Required Reading



   -Icy Version 1.0.0, 14-DEC-2016, ML (JPL), EDW (JPL)


   compute range bounds for type 2 dsk segment

Wed Apr  5 17:58:00 2017