d.rast.arrow(1)        Grass User's Manual	  d.rast.arrow(1)



NNAAMMEE
       dd..rraasstt..aarrrrooww   -  Draws	arrows	representing  cell aspect
       direction for a raster map layer.
       _(_G_R_A_S_S _D_i_s_p_l_a_y _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       dd..rraasstt..aarrrrooww
       dd..rraasstt..aarrrrooww hheellpp
       dd..rraasstt..aarrrrooww  [mmaapp==_n_a_m_e]  [ttyyppee==_n_a_m_e]   [aarrrrooww__ccoolloorr==_n_a_m_e]
       [ggrriidd__ccoolloorr==_n_a_m_e] [xx__ccoolloorr==_n_a_m_e] [uunnkknnoowwnn__ccoolloorr==_n_a_m_e]

DDEESSCCRRIIPPTTIIOONN
       _d_._r_a_s_t_._a_r_r_o_w  is  designed  to help users better visualize
       surface water flow direction, as indicated  in  an  aspect
       raster  map  layer.   There  are  two  ways to specify the
       aspect layer the program is to use.  The first is to  dis-
       play  the  aspect map layer on the graphics monitor before
       running _d_._r_a_s_t_._a_r_r_o_w.  The second method involves  setting
       the  _m_a_p  parameter to the name of the desired aspect map.
       This allows the arrows to be drawn  over  any  other  maps
       already displayed on the graphics monitor.


       _d_._r_a_s_t_._a_r_r_o_w  will  draw an arrow over each displayed cell
       to indicate in which direction the cell slopes.	An  arrow
       can point in one of eight directions.  If the aspect layer
       has a  category	value  denoting  locations  of	"unknown"
       aspect,	_d_._r_a_s_t_._a_r_r_o_w  draws a question mark over the dis-
       played cells of that category.  Cells of  category  0  (no
       data) will be marked with an "X".


	NNoottee::	Arrows	are  cell  size and cannot be seen if the
       raster map is relatively close in scale.  From  a  command
       line  mode,  the user cannot run _d_._r_a_s_t_._a_r_r_o_w and then run
       _d_._z_o_o_m and still  see  the  arrows.   The  zooming  action
       erases  the  arrows  and  the  user  must run _d_._r_a_s_t_._a_r_r_o_w
       again.

OOPPTTIIOONNSS
   PPaarraammeetteerrss::
       mmaapp==_n_a_m_e
	      Name of an existing raster map  layer  to  be  dis-
	      played.

       ttyyppee==_n_a_m_e
	      Type of existing raster data to be displayed.
	      Options:	grass, agnps, answers
	      Default:	grass
	      Using  this information, _d_._r_a_s_t_._a_r_r_o_w uses internal
	      information to convert category values into  appro-
	      priate arrow directions.

       aarrrrooww__ccoolloorr==_n_a_m_e
	      Color in which arrows will be drawn.
	      Options:	 white, red, orange, yellow, green, blue,
	      indigo, violet, magenta, brown, gray, black
	      Default:	green

       ggrriidd__ccoolloorr==_n_a_m_e
	      Color in which grid outlines will be drawn.
	      Options:	white, red, orange, yellow, green,  blue,
	      indigo, violet, magenta, brown, gray, black
	      Default:	gray

       xx__ccoolloorr==_n_a_m_e
	      Color in which x's will be drawn.
	      Options:	 white, red, orange, yellow, green, blue,
	      indigo, violet, magenta, brown, gray, black
	      Default:	white

       uunnkknnoowwnn__ccoolloorr==_n_a_m_e
	      Color in which unknown  information  will  be  dis-
	      played.
	      Options:	 white, red, orange, yellow, green, blue,
	      indigo, violet, magenta, brown, gray, black
	      Default:	red


SSEEEE AALLSSOO
       _d_._f_r_a_m_e

       _d_._r_a_s_t

       _d_._r_a_s_t_._e_d_i_t

       _d_._r_a_s_t_._n_u_m

       _d_._z_o_o_m

       _g_._r_e_g_i_o_n

       _r_._m_a_s_k

       _r_._s_l_o_p_e_._a_s_p_e_c_t

       _p_a_r_s_e_r

AAUUTTHHOORR
       Chris Rewerts, Agricultural Engineering, Purdue University

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_3 _$



GRASS 5.0					  d.rast.arrow(1)
