d.3d(1) 	       Grass User's Manual		  d.3d(1)



NNAAMMEE
       dd..33dd  -	Displays three-dimensional images based on raster
       map layers.
       _(_G_R_A_S_S _D_i_s_p_l_a_y _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       dd..33dd
       dd..33dd hheellpp
       dd..33dd   [--llaann]   mmaapp==_n_a_m_e   eelleevvaattiioonn==_n_a_m_e    [ffrroomm__ccoooorrddii--
       nnaattee==_x_,_y_,_z]   [ttoo__ccoooorrddiinnaattee==_x_,_y_,_z]   [eexxaaggggeerraattiioonn==_v_a_l_u_e]
       [lliinneess==_v_a_l_u_e] [ffiieelldd==_v_a_l_u_e] [ccoolloorr==_n_a_m_e] [bbooxx==_n_a_m_e]

DDEESSCCRRIIPPTTIIOONN
       _d_._3_d displays three-dimensional graphic	images	based  on
       GRASS  raster map layers.  The user identifies the viewing
       point, the line of sight, a vertical exaggeration  factor,
       the viewing angle (field of view), the frequency and color
       of vector grid lines to appear in the display, the map  to
       be displayed in 3-d, and the map whose category values are
       to be used as elevation values in the 3-dimensional image.


       The  program  will  be  run  non-interactively if the user
       specifies all needed parameter values and flag settings on
       the  command  line.  Alternately, the user can simply type
       dd..33dd on the command line; in this case, the  program  will
       prompt  the  user  for  parameter values and flag settings
       using the standard interface described in the manual entry
       for _p_a_r_s_e_r.


       Three-dimensional images can also be generated through the
       GRASS _d_._d_i_s_p_l_a_y program.

OOPPTTIIOONNSS
   FFllaaggss::
       --ll     Display _l_i_n_e_s only, without displaying  the  raster
	      base _m_a_p.

       --aa     Each  grid-cell  is  rendered  using four elevation
	      coordinates: one for each corner. By default,  each
	      corner  takes  the  value  of  the grid-cell to the
	      lower right. With the -a option each corner is cal-
	      culated to be an average of the four bordering cell
	      elevation values.

       --nn     Show null elevations.


   PPaarraammeetteerrss::
       mmaapp==_n_a_m_e
	      The raster map layer used  to  generate  the  color
	      shown  in the 3-d output (i.e., the map whose x and
	      y values will be displayed, using the z values pre-
	      sent in the _e_l_e_v_a_t_i_o_n map layer.)

       eelleevvaattiioonn==_n_a_m_e
	      The  raster map used to generate the texture in the
	      3-d image (i.e., the map whose category values will
	      become  the  elevation  values  in the 3-d map dis-
	      played). This need not be an elevation  map  layer,
	      although elevation is commonly used.
	      Default: elevation

       ffrroomm__ccoooorrddiinnaattee==_x_,_y_,_z
	      Coordinates  of  the  viewing point, given as: _n_o_r_-
	      _t_h_i_n_g_,_e_a_s_t_i_n_g_,_e_l_e_v_a_t_i_o_n.	The default  _f_r_o_m___c_o_o_r_d_i_-
	      _n_a_t_e  value is appropriate for the spearfish sample
	      data set.
	      Default: Calculated at run-time just south-west  of
	      the south-west corner.

       ttoo__ccoooorrddiinnaattee==_x_,_y_,_z
	      Coordinates  of  center  of  view,  given  as: _n_o_r_-
	      _t_h_i_n_g_,_e_a_s_t_i_n_g_,_e_l_e_v_a_t_i_o_n.	The default _t_o___c_o_o_r_d_i_n_a_t_e
	      value  is appropriate for the spearfish sample data
	      set.
	      Default: Calculated at run-time as  the  center  of
	      the image

       eexxaaggggeerraattiioonn==value
	      Vertical	exaggeration factor. This value is multi-
	      plied by the "elevation" values  (category  values)
	      in  the _e_l_e_v_a_t_i_o_n map layer.  As the vertical coor-
	      dinates are exaggerated, the elevation (z) value of
	      the  center  of  view (the _t_o___c_o_o_r_d_i_n_a_t_e) should be
	      increased.
	      Default: 2.0

       lliinneess==_v_a_l_u_e
	      North-south and east-west  trending  lines  can  be
	      drawn  on  the 3-d image output, to enhance the 3-d
	      effect.  The _l_i_n_e_s value specifies  the  number  of
	      rows  and  columns  to skip between lines.  0 means
	      "display no lines". Lines  will  be  drawn  in  the
	      _c_o_l_o_r  stated.   The user can elect to only display
	      these lines, without displaying the _m_a_p, by setting
	      the -l flag.
	      Default: 1

       ffiieelldd==_v_a_l_u_e
	      The  field  of  view  (viewing angle) in the image,
	      stated in degrees.
	      Default: 30

       ccoolloorr==_n_a_m_e
	      Color of vector _l_i_n_e_s drawn on the output.
	      Options: color, white, red, orange, yellow,  green,
	      blue, indigo, violet, gray, black
	      Default: gray



       The  resulting  three-dimensional  image  is  drawn in the
       active frame on the  graphics  monitor.	The  user  should
       select  and  erase  the full graphics monitor frame before
       running _d_._3_d to prepare the screen for graphics.  Refer to
       the  GRASS  program  _3_d_._v_i_e_w_._s_h for a demonstration of the
       _d_._3_d program.

IINNTTEERRAACCTTIIVVEE MMOODDEE
       The interactive mode prompts for the raster map to be ren-
       dered, the raster map to be queried for elevation informa-
       tion, and an optionally saved set of saved viewing parame-
       ters.  The user is then presented with a form in which the
       options can be modified.


       It is suggested that the following procedure  be  used  to
       efficiently  find  the  correct	viewing parameters. Start
       with a gross grid (by  default,	a  resolution  is  chosen
       which  limits  the total number of rows and columns), dis-
       play lines only, set line colors to  "color"  (lines  take
       their  color from the map), set the box color to something
       other than "none", and use  the	default  viewing  coordi-
       nates.  Experiment  with the viewing coordinates until the
       map is positioned in a desireable configuration. When  the
       map  is	lined up correctly, set the display resolution as
       low as you like for a final image.

BBUUGGSS
       Several additions to this  program  have  been  suggested.
       These include the following:

	       Border  the  image  with a visually appealing cur-
	      tain.

	       Add x,y,z coordinates and scale information to the
	      displayed 3-d image.

	       Provide	a  graphic-oriented  user  interface  for
	      identifying viewing parameters.

	       Display output more quickly by  doing  mathematics
	      in integers.

	       Add the option of plotting vector map layers.


SSEEEE AALLSSOO
       _3_d_._v_i_e_w_._s_h_,

       _d_._d_i_s_p_l_a_y_,

       _d_._e_r_a_s_e_,

       _d_._f_r_a_m_e_,

       _p_a_r_s_e_r

AAUUTTHHOORR
       James   Westervelt,  U.S.  Army	Construction  Engineering
       Research Laboratory

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_2 _$



GRASS 5.0						  d.3d(1)
