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NAME

       i.ortho.photo  - Menu driver for the photo imagery programs.

KEYWORDS

       imagery, orthorectify

SYNOPSIS

       i.ortho.photo
       i.ortho.photo --help
       i.ortho.photo group=name productname=string  [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:
       group=name [required]
           Name of imagery group for ortho-rectification

       productname=string [required]
           Name of Modules
           Options:  i.group,  i.ortho.target,  i.ortho.elev,  i.ortho.camera, g.gui.photo2image,
           i.ortho.init, g.gui.image2target, i.ortho.rectify
           i.group: 1 - Select/Modify imagery group
           i.ortho.target: 2 - Select/Modify imagery group target
           i.ortho.elev: 3 - Select/Modify target elevation model
           i.ortho.camera: 4 - Select/Modify imagery group camera
           g.gui.photo2image: 5 - Compute image-to-photo transformation
           i.ortho.init: 6 - Initialize exposure station parameters
           g.gui.image2target: 7 - Compute ortho-rectification parameters
           i.ortho.rectify: 8 - Ortho-rectify imagery files

DESCRIPTION

       i.ortho.photo is a menu to launch the different parts of the ortho  rectification  process
       of  aerial  imagery.  i.ortho.photo  allows  the user to ortho-rectify imagery group files
       consisting of  several  scanned  aerial  photographs  (raster  maps)  of  a  common  area.
       i.ortho.photo guides the user through 8 steps required to ortho-rectify the raster maps in
       a single imagery group. Alternatively, all  the  steps  can  be  performed  separately  by
       running the appropriate modules.

           ·   Initialization Options

           ·   Create/Modify imagery group to be orthorectified: i.group

           ·   Select/Modify target location and mapset for orthorectification: i.ortho.target

           ·   Select/Modify target elevation model used for orthorectification: i.ortho.elev

           ·   Create/Modify camera file of imagery group: i.ortho.camera

           ·   Transformation Parameters Computation

           ·   Compute image-to-photo transformation: g.gui.photo2image

           ·   Initialize parameters of camera: i.ortho.init

           ·   Compute    ortho-rectification    parameters    from    ground   control   points:
               g.gui.image2target

           ·   Ortho-rectification

           ·   Ortho-rectify imagery group: i.ortho.rectify

       The ortho-rectification procedure in GRASS GIS places the image pixels on the  surface  of
       the  earth  by  matching  the  coordinate  system  of  the  aerial  image in pixels (image
       coordinate system) and the coordinate system of the camera sensor  in  millimetres  (photo
       coordinate  system)  for  the  interior  orientation  of  the  image,  and  further to the
       georeferenced coordinate  system  defined  by  projection  parametres  (target  coordinate
       system) for exterior orientation.

EXAMPLE

       Five groups of input parameters are required for ortho-rectification:

           ·   Aerial image (images),

           ·   Exposure  and  characteristics  of  the  camera,  i.e.  its  coordinates in target
               coordinate system and height above sea level, focal length, yaw, pitch  and  roll,
               dimensions of the camera sensor and resolution of aerial images,

           ·   Reference  surface,  i.e.  digital elevation model in the target coordinate system
               used to normalize the terrain undulation,

           ·   Topographic reference map used to find corresponding ground control points and/or,

           ·   Coordinates of ground control points in the target coordinate system.
       Example of an input oblique image in a source location

       To ortho-rectify aerial images the user has to follow  the  menu  options  step  by  step.
       Alternatively,  all  the  steps  can  be performed separately by running the corresponding
       modules.

       The aerial photos shall be stored in a source location - a  general  Cartesian  coordinate
       system (XY). Digital elevation model and a map reference (topo sheet or other map used for
       ground control point matching) shall be stored  in  a  target  location  in  a  real-world
       coordinate system (e.g. ETRS33).

       The steps to follow are described below:

       1      Create/Modify imagery group to be orthorectified: i.group

       This step is to be run in the source location.

       In this first step an imagery group of aerial images for ortho-rectification is created or
       modified. The current imagery group is displayed at the top of the menu. You may select  a
       new  or existing imagery group for the ortho-rectification. After choosing this option you
       will be prompted for the name of a new or existing imagery group. As a result, a new  file
       mapset/group/name_of_group/REF  is  created  that  contatins  the names of all images in a
       group.
       IMG_0020 source_mapset
       IMG_0021 source_mapset
       IMG_0022 source_mapset

       2      Select/Modify target location and mapset for orthorectification: i.ortho.target

       This step is to be run in the source location.

       The target location and mapset may be selected  or  modified  in  Step  2.   You  will  be
       prompted   for   the  names  of  the  projected  target  location  and  mapset  where  the
       ortho-rectified raster maps will reside. The target location is  also  the  location  from
       which  the  elevation  model  (raster map) will be selected (see Step 3). In Step 2, a new
       file mapset/group/name_of_group/TARGET is created contatining the names of target location
       and mapset.
       ETRS_33N
       target_mapset

       3      Select/Modify target elevation model used for orthorectification: i.ortho.elev

       This step is to be run in the source location.

       Step  3  allows  you  to  select the raster map from the target location to be used as the
       elevation  model.  The  elevation  model  is  required  for  both   the   computation   of
       photo-to-target  parameters  (Step 6) and for the ortho-rectification of the imagery group
       files (Step 8).  The raster map selected for the elevation model should cover  the  entire
       area  of the image group to be ortho-rectified. DTED and DEM files are suitable for use as
       elevation model in the ortho-rectification program.  In Step 3 you will  be  prompted  for
       the  name  of  the raster map in the target location that you want to use as the elevation
       model. As a result of  this  step,  a  new  file  mapset/group/name_of_group/ELEVATION  is
       created contatining the name and mapset of the chosen DEM.
       elevation layer :ELEVATION
       mapset elevation:target_mapset
       location        :ETRS_33N
       math expression :(null)
       units           :(null)
       no data values  :(null)

       4
               Create/Modify camera file of imagery group: i.ortho.camera

       This step is to be run in the source location.

       In  Step  4  you  may  select or create a 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 fiducial or reseau
       marks. The most important characteristic of the camera is its focal  length.  Fiducial  or
       reseau  marks  locations  are  required  to  compute the scanned image to photo coordinate
       transformation parameter (Step 5). Two  new  files  are  created  in  this  step:  a  file
       mapset/group/name_of_group/CAMERA, contatining the name of the reference camera and a file
       mapset/camera/name_of_reference, contatining the camera parameters.
       CAMERA NAME   sony
       CAMERA ID     123
       CAMERA XP     0
       CAMERA YP     0
       CAMERA CFL    16
       NUM FID       4
             0 -11.6 0
             1 0 7.7
             2 11.6 0
             3 0 -7.7

       5
               Compute image-to-photo transformation: g.gui.photo2image

       This step is to be run in the source location.

       The scanned image to  photo  coordinate  transformation  parameters,  i.e.  the  "interior
       orientation",  is  computed  in Step 5. In this interactive step you associate the scanned
       reference points (fiducials, reseau marks, etc.)  with their known photo coordinates  from
       the  camera  reference  file. A new file mapset/group/name_of_group/REF_POINTS is created,
       contatining a list of pairs of coordinates in image and photo coordinate systems.
       # Ground Control Points File
       #
       # target location: XY
       # target mapset: source_mapset
       # source  target  status
       # east north east north (1=ok, 0=ignore)
       #-------------------------------------------------------------
       0 1816     -11.6 0.0     1
       2728 3632     0.0 7.7     1
       5456 1816     11.6 0.0     1
       2728 0.0     0.0 -7.7     1
       Step 5: Image-to-photo transformation of an oblique image

       6
               Initialize parameters of camera: i.ortho.init

       This step is to be run in the source location.

       In Step 6, initial camera  exposure  station  parameters  and  initial  variances  may  be
       selected or modified.

           ·   X: East aircraft position;

           ·   Y: North aircraft position;

           ·   Z: Flight heigh above surface;

           ·   Omega  (roll):  Raising  or  lowering  of the wings (turning around the aircraft’s
               axis);

           ·   Phi (pitch): Raising or lowering of  the  aircraft’s  front  (turning  around  the
               wings’ axis);

           ·   Kappa  (yaw): Rotation needed to align the aerial photo to true north: needs to be
               denoted as +90° for clockwise turn and -90° for a counter-clockwise turn.
       Principle of pitch and yaw

       In Step 6, a new file mapset/group/name_of_group/INIT_EXP is created,  contatining  camera
       parameters.
       INITIAL XC    215258.345387
       INITIAL YC    6911444.022270
       INITIAL ZC    1101.991120
       INITIAL OMEGA 0.000000
       INITIAL PHI   -0.168721
       INITIAL KAPPA 3.403392
       VARIANCE XC    5.000000
       VARIANCE YC    5.000000
       VARIANCE ZC    5.000000
       VARIANCE OMEGA 0.000000
       VARIANCE PHI   0.020153
       VARIANCE KAPPA 0.017453
       STATUS (1=OK, 0=NOT OK) 0

       7
               Compute    ortho-rectification    parameters    from    ground   control   points:
              g.gui.image2target

       This step is to be run in the target location.

       The photo to  target  transformation  parameters,  i.e.  the  "exterior  orientation",  is
       computed  in  Step  7.  In this interactive step, control points are marked on one or more
       imagery group files and associated with  the  known  standard  (e.g.  UTM)  and  elevation
       coordinates.   Reasonable rectification results can be obtained with around twelve control
       points   well   distributed   over   the   image.    In   this   step,    a    new    file
       mapset/group/name_of_group/CONTROL_POINTS  is  created,  contatining  a  list  of pairs of
       coordinates of ground control points in photo and target coordinate systems.
       # Ground Control Points File
       #
       # target location: ETRS_33N
       # target mapset: target_mapset
       #    source                          target                     status
       #    east north     height          east     north     height    (1=ok, 0=ignore)
       #------------------------------     ----------------------    ---------------
       98.3679932698 906.327649515 0.0    1.0 5.0  100.0             1
       733.293023813 1329.61100321 0.0    2.0 6.0  100.0             1
       1292.6317412  1703.76325335 0.0    3.0 7.0  100.0             1
       1625.54617472 1368.11694482 0.0    4.0 6.0  100.3             1
       3239.82849913 1390.97403968 0.0    7.4 6.0  100.3             1
       1570.09788497 2790.06537829 0.0    3.0 11.0 100.0             1
       Step 7: Detail of ground control points matching in an oblique image and terrain model

       8
               Ortho-rectify imagery group: i.ortho.rectify

       This step is to be run in the source location.

       Step 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.
       Step 8: Ortho-rectified oblique image As a  result,  the  ortho-rectified  raster  map  is
       available for visualization and further image analysis.

SEE ALSO

           g.gui.image2target,    g.gui.photo2image,   i.group,   i.ortho.camera,   i.ortho.elev,
       i.ortho.init, i.ortho.rectify, i.ortho.target

AUTHOR

       Mike Baba,  DBA Systems, Inc.
       GRASS development team, 199?-2017

       Last changed: $Date: 2018-01-09 18:03:03 +0100 (Tue, 09 Jan 2018) $

SOURCE CODE

       Available at: i.ortho.photo source code (history)

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       © 2003-2019 GRASS Development Team, GRASS GIS 7.6.1 Reference Manual