v.build.polylines(1)	      Grass User's Manual	  v.build.polylines(1)



NNAAMMEE
       _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s  - Build polylines from lines.

       _(_G_R_A_S_S Vector Program)

SSYYNNOOPPSSIISS
       vv..bbuuiilldd..ppoollyylliinneess

       vv..bbuuiilldd..ppoollyylliinneess hheellpp

       vv..bbuuiilldd..ppoollyylliinneess  [--aaccooqq ] iinnppuutt_n_a_m_e  output_n_a_m_e  _t_y_p_e_=_n_a_m_e

DDEESSCCRRIIPPTTIIOONN
       _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s   builds  polylines from the lines in a binary vector
       file.  It outputs the polylines in either binary or ASCII  vector  for-
       mat, and if requested, copies the attribute and category files from the
       original file.


       A line is a single straight line segment defined by one start node, one
       end  node  and no other nodes.  A polyline is also defined by one start
       node, one end node and no other nodes, but is made of two or more  con-
       secutive  straight  line  segments.   The  connections between the con-
       stituent line segments of a polyline do not appear as nodes in the vec-
       tor map.


       Polylines  provide  the most appropriate representation of curved lines
       when it is important that nodes serve to define	topology  rather  than
       geometry.   Curved  lines are usually digitized as polylines, but these
       are sometimes broken into their constituent straight line segments dur-
       ing  conversion from one data format to another.  _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s
	can  be used to rebuild such broken polylines.



OOPPTTIIOONNSS
       The  program  can  be run either non-interactively or interactively. To
       run _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s
	non-interactively, the user must specify _i_n_p_u_t	and _o_u_t_p_u_t  file names
       on the command line.  The line  _t_y_p_e  and flags are optional.


       To  run	_v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s   interactively  the user should simply type
       vv..bbuuiilldd..ppoollyylliinneess
	on the command line, in which case the program will prompt for parame-
       ter  values  using the standard GRASS interface described in the manual
       entry for _p_a_r_s_e_r .




       FFllaaggss::

       --aa  Make the _o_u_t_p_u_t  file an ASCII vector map instead of a binary  vec-
	   tor map.

       --cc  Copy  the  attribute  (`dig_att')  and  category (`dig_cats') files
	   associated with the _i_n_p_u_t  file to new files with the _o_u_t_p_u_t   file
	   name.   You	should	set  this  flag if you wish to retain category
	   information in the new binary file.

       --oo  Silently overwrite the _o_u_t_p_u_t  file if it  exists  in  the  current
	   mapset. When this flag is not set _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s	will refuse to
	   create the  _o_u_t_p_u_t  file if a file  of  the	same  name  exists  in
	   either the `dig' or the `dig_ascii' mapset elements.

       --qq  Run (relatively) quietly.  Specifically, do not provide information
	   (including warnings) about each polyline.



       PPaarraammeetteerrss::

       iinnppuutt_n_a_m_e
	   The name of a binary vector map layer containing lines (and	possi-
	   bly some polylines).

       oouuttppuutt_n_a_m_e
	   The	name  of  the  ASCII vector map to be created in the dig_ascii
	   mapset  element.

       ttyyppee_n_a_m_e
	   The type of each new polyline can be set from the  _i_n_p_u_t   map,  or
	   alternatively  all  new  polylines  can  be	bulk labeled as either
	   lines, area edges, or points.

	   Options: source, line, area, point.


NNOOTTEESS
       For  full  functionality  _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s   requires  _v_._s_u_p_p_o_r_t   and
       _v_._i_n_._a_s_c_i_i .


       If  the	lines  that  make  up  a polyline are of different types, then
       _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s
	will set the type from the first constituent line.   _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s
       will issue a warning unless the flag _-_q	has  been set.	It is possible
       to keep a list of all such warnings by redirecting  standard output  to
       a file.


       If  the	lines  that make up a polyline have different attribute values
       then _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s  will set the attribute value of the polyline to
       that  of  the last line (this is the behaviour of  _v_._s_u_p_p_o_r_t , which is
       used to assign the attribute values).  Any warnings issued by _v_._s_u_p_p_o_r_t
       will be visible unless the flag _-_q  has been set.


       _v_._b_u_i_l_d_._p_o_l_y_l_i_n_e_s  correctly handles _i_n_p_u_t  maps containing lines, area
       edges and points.  Lines and area edges will be converted to  polylines
       of  the desired type.  Areas are only guaranteed to be preserved if the
       constituent lines of the polylines that define them are all area  edges
       in   the  input	map. Points will remain points provided that _t_y_p_e  has
       been set to `source'.  It is possible to convert lines and  area  edges
       to points or vice versa, but this is rarely useful.


       Use _v_._i_m_p_o_r_t  to convert an ASCII _o_u_t_p_u_t  map to a binary vector map.



SSEEEE AALLSSOO
       _v_._i_m_p_o_r_t, _v_._s_u_p_p_o_r_t, _v_._i_n_._a_s_c_i_i, _p_a_r_s_e_r



AACCKKNNOOWWLLEEDDGGEEMMEENNTTSS
       This  program  was  written  during the author's tenure of a Leverhulme
       Special Research Fellowship at University College London.



AAUUTTHHOORR
       Mark Lake, Institute of Archaeology, University College London.



BBUUGGSS
       Please email mark.lake@ucl.ac.uk if you find any bugs.



       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_5 _$



GRASS 5.0						  v.build.polylines(1)
