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Required Reading


   CSPICE_DSKV02 returns specified vertices from a type 2 DSK segment.

   For important details concerning this module's function, please refer to
   the CSPICE routine dskv02_c.



      handle    the handle of a DSK file containing a type 2
                segment from which data are to be fetched.

      dladsc    the DLA descriptor associated with the segment
                from which data are to be fetched.

      start     the ID of the first vertex to be fetched from the
                segment designated by `handle' and `dladsc'. The ID
                of a vertex is its ordinal position within the
                segment. Vertex IDs range from 1 to NV, where NV is
                the number of vertices in the segment.

                Note that Fortran-style 1-based indexing is used for
                vertex IDs because these IDs must be consistent with
                the IDs used in DSK files, across all languages
                supported by SPICE.

      room      the maximum number of vertices to return.

   the call:

      cspice_dskv02, handle, dladsc, start, room, vrtces


      vrtces    the array representing a contiguous set of `n' vertices,
                where `n' is between 1 and `room' inclusive. The returned
                vertices are arranged in order of increasing vertex ID.
                The IDs of the returned vertices range from



                    start + n - 1

                Each vertex is a 3-vector. The correspondence of elements
                of `vrtces' with the elements of the set of vertices
                contained in the segment is:

                   vrtces[0,0]      segment_vertex_set[0, start]
                   vrtces[1,0]      segment_vertex_set[1, start]
                   vrtces[2,0]      segment_vertex_set[2, start]
                     ...             ...
                   vrtces[0,n-1]    segment_vertex_set[0, start+n-1]
                   vrtces[1,n-1]    segment_vertex_set[1, start+n-1]
                   vrtces[2,n-1]    segment_vertex_set[2, start+n-1]

                The vertices are expressed in the body-fixed
                reference frame of the segment designated by `handle'
                and `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.

                If an error occurs on the call, `vrtces' is


   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.



Required Reading



   -Icy Version 1.0.0, 04-APR-2017, ML (JPL), EDW (JPL)


   return specified vertices from type 2 DSK segment

Wed Apr  5 17:58:00 2017