i.ortho.photo(1)       Grass User's Manual	 i.ortho.photo(1)



NNAAMMEE
       ii..oorrtthhoo..pphhoottoo  -  An  interactive imagery function for the
       ortho-rectification of imagery group files.
       _(_G_R_A_S_S _I_m_a_g_e _P_r_o_c_e_s_s_i_n_g _P_r_o_g_r_a_m_)

SSYYNNOOPPSSIISS
       ii..oorrtthhoo..pphhoottoo

DDEESSCCRRIIPPTTIIOONN
       _i_._o_r_t_h_o_._p_h_o_t_o allows the  user  to  ortho-rectify  imagery
       group files.  An imagery group consists of several scanned
       aerial  photographs  (raster  files)  of  a  common  area.
       Imagery	groups can be created or modified using the GRASS
       Image Processing Program _i_._g_r_o_u_p, or using the first  menu
       option  described  below.   _i_._o_r_t_h_o_._p_h_o_t_o  guides the user
       through the steps required  to  ortho-rectify  the  raster
       files in a single imagery group.


       The first menu in _i_._o_r_t_h_o_._p_h_o_t_o provides the user with the
       following options:

       Initialization Options:
	      1) Select/Modify imagery group

	      2) Select/Modify imagery group target

	      3) Select/Modify target elevation model

	      4) Select/Modify imagery group camera


       Transformation Parameter Computation:
	      5) Compute image-to-photo transformation parameters

	      6) Initialize exposure station parameters

	      7)  Compute  photo-to-target transformation parame-
	      ters


       Ortho-rectification Option:
	      8) Ortho-rectify imagery group raster files

       RETURN to exit
	      >

       To ortho-rectify aerial images the user has to follow  the
       menu  options  step  by	step. Generally the user builds a
       target location containing a projected DEM and a map  ref-
       erence (topo sheet or other map). Another xy-location will
       contain the aerial photo. The entire rectification process
       is started within the xy-location. First the target to the
       projected location has to  be  set  (i.target),	then  the
       image  references (fiducial points) will be defined. After
       describing the camera parameters,  reference  points  from
       aerial  image  to  the topo sheet from the target location
       will be set. The local elevation will be  taken	from  the
       target DEM. Finally the aerial image will be rectified.


       The options to follow are described as follows:

       _S_e_l_e_c_t_/_M_o_d_i_f_y _i_m_a_g_e_r_y _g_r_o_u_p
	      The  current imagery group is display at the top of
	      the previous menu.  You may select another (new  or
	      existing) imagery group for the ortho-rectification
	      program using option (1).   After  choosing  option
	      (1)  you	will be prompted for the name of a new or
	      existing imagery group.  Option (1) using the GRASS
	      Image  Processing  Program _i_._g_r_o_u_p, for creation or
	      modification of imagery groups.  For more  informa-
	      tion  on	imagery  group	creation  or modification
	      please the the GRASS manual page for _i_._g_r_o_u_p.

       _S_e_l_e_c_t_/_M_o_d_i_f_y _i_m_a_g_e_r_y _g_r_o_u_p _t_a_r_g_e_t
	      The target location and mapset may be  selected  or
	      modified	using  option (2).  After choosing option
	      (2) you will be prompted for the names of the  tar-
	      get  location and mapset, where the ortho-rectified
	      raster files will reside.  The target  location  is
	      also  the  location  from which the elevation model
	      (raster file) will be selected -- see  option  (3).
	      Option  (2) uses the GRASS Image Processing Program
	      _i_._t_a_r_g_e_t, for  selection	or  modification  of  the
	      imagery group target location and mapset.  For more
	      information on imagery group selection or modifica-
	      tion please the the GRASS manual page for _i_._t_a_r_g_e_t.

       _S_e_l_e_c_t_/_M_o_d_i_f_y _i_m_a_g_e_r_y _g_r_o_u_p
	      Option (3) allows you to	select	the  raster  file
	      from  the  target location to be used as the eleva-
	      tion model.  The elevation model	is  required  for
	      both  the computation of photo-to-target parameters
	      (option 6) and for the ortho-rectification  of  the
	      imagery  group  files  (option 8).  The raster file
	      select for the elevation	model  should  cover  the
	      entire  area  of the image group to be ortho-recti-
	      fied.  Currently, the elevation model  raster  file
	      is expected to be in units of meters.  DTED and DEM
	      files are suitable for use as the  elevation  model
	      in  the  ortho-rectification program.  After selec-
	      tion option (3) you will be prompted for	the  name
	      of  the raster file in the target location that you
	      want to use as the elevation model.

       _S_e_l_e_c_t_/_M_o_d_i_f_y _i_m_a_g_e_r_y _g_r_o_u_p _c_a_m_e_r_a
	      Using option (4) you may select or create an camera
	      reference  file  that will be used with the current
	      imagery group.  A camera	reference  file  contains
	      information  on the internal characteristics of the
	      aerial camera, as well as the geometry of the fidu-
	      cial  or	reseau marks.  The most important charac-
	      teristic of the camera is its focal length.   Fidu-
	      cial or reseau marks locations are required to com-
	      pute the scanned image to  photo-coordinate  trans-
	      formation   parameter   (option  5).   For  a  more
	      detailed description of option (4) please  see  the
	      GRASS manual page for _p_h_o_t_o_._c_a_m_e_r_a.

       _C_o_m_p_u_t_e _i_m_a_g_e_-_t_o_-_p_h_o_t_o _t_r_a_n_s_f_o_r_m_a_t_i_o_n _p_a_r_a_m_e_t_e_r_s
	      The  scanned  image to photo-coordinate transforma-
	      tion parameters are computed using option (5).   In
	      this  interactive option you associate scanned ref-
	      erence points (fiducials, reseau marks, etc.)  with
	      their  known photo coordinates from the camera ref-
	      erence  file.   Complete	documentation  for   this
	      option   is   available	under  the  manual  entry
	      _p_h_o_t_o_._2_i_m_a_g_e.

       _C_o_m_p_u_t_e _p_h_o_t_o_-_t_o_-_t_a_r_g_e_t _t_r_a_n_s_f_o_r_m_a_t_i_o_n _p_a_r_a_m_e_t_e_r_s
	      The photo to target transformation  parameters  are
	      compute  using  option(6).  Here control points are
	      marked on one or more imagery group files and asso-
	      ciated  with  there known UTM and elevation coordi-
	      nates.  Complete documentation for this  option  is
	      available under the manual entry _p_h_o_t_o_._2_t_a_r_g_e_t.

       _S_e_l_e_c_t _i_n_i_t_i_a_l _e_x_p_o_s_u_r_e _s_t_a_t_i_o_n _p_a_r_a_m_e_t_e_r_s
	      If  option (7) is selected, initial camera exposure
	      station parameters and  initial  variances  may  be
	      selected	or  modified.  Complete documentation for
	      this option is available	under  the  manual  entry
	      _p_h_o_t_o_._i_n_i_t.

       _O_r_t_h_o_-_p_h_o_t_o _i_m_a_g_e_r_y _g_r_o_u_p _f_i_l_e_s
	      Option  (8)  is  used  to  perform the actual image
	      ortho-rectification after all of the transformation
	      parameters  have	been  computed.   Ortho-rectified
	      raster files will be created in the target location
	      for  each  selected  imagery  group  file.  You may
	      select either the  current  window  in  the  target
	      location	or  the  minimal  bounding window for the
	      ortho-rectified image.  Complete documentation  for
	      this  option  is	available  under the manual entry
	      _p_h_o_t_o_._r_e_c_t_i_f_y.


NNOOTTEESS
       _i_._o_r_t_h_o_._p_h_o_t_o currently requires the elevation model to be
       in  meters, and the target location to be a UTM coordinate
       system.

SSEEEE AALLSSOO
       _p_h_o_t_o_._c_a_m_e_r_a

       _p_h_o_t_o_._2_i_m_a_g_e

       _p_h_o_t_o_._2_t_a_r_g_e_t

       _p_h_o_t_o_._i_n_i_t

       _p_h_o_t_o_._r_e_c_t_i_f_y

AAUUTTHHOORR
       Mike Baba,  DBA Systems, Inc.


       Updated rectification  and  elevation  map  to  FP  1/2002
       Markus Neteler

       _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					 i.ortho.photo(1)
