NAME

       i.photo.init   -  Interactively  creates  or modifies entries in a camera initial exposure
       station file for imagery group referenced by a sub-block.

KEYWORDS

       imagery, orthorectify

SYNOPSIS

       i.photo.init
       i.photo.init help
       i.photo.init group=name  [--verbose]  [--quiet]

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

DESCRIPTION

       Aerial photographs may be either vertical or oblique. Vertical photographs  can  be  truly
       vertical  (nadir),  or  slightly  tilted  (less  than 3 degree from the vertical). Usually
       aerial photos are tilted to some degree. We refer to the term vertical photograph up to  a
       tilt of 3 degree.
       Oblique  aerial photographs are purposely taken with an angle between 3 and 90 degree from
       the nadir direction.

       The use of i.photo.init (menu 6) is only required when  rectifying  a  tilted  or  oblique
       aerial photo.

       i.photo.init  creates  or  modifies  entries in a camera initial exposure station file for
       imagery group referenced by a sub-block.  These entries include: the  (XC,YC,ZC)  standard
       (e.g.  UTM)  approximate  coordinates of the camera exposure station; initial roll, pitch,
       and yaw angles (in degrees) of the cameras attitude; and the a priori standard  deviations
       for  these  parameters.  During  the  imagery program, i.photo.rectify, the initial camera
       exposure station file is used for computation of the ortho-rectification  parameters.   If
       no  initial  camera  exposure station file exist, the default values are computed from the
       control points file created in <A HREF="i.photo.2target.html">i.photo.2target.

       The following menu is displayed:
               Please provide the following information
            INITIAL XC: Meters                __________
            INITIAL YC: Meters                __________
            INITIAL ZC: Meters                __________
            INITIAL omega (roll) degrees:     __________
            INITIAL phi  (pitch) degrees:     __________
            INITIAL kappa  (yaw) degrees:     __________
            Standard Deviation XC: Meters     __________
            Standard Deviation YC: Meters     __________
            Standard Deviation ZC: Meters     __________
            Std. Dev. omega (roll) degrees:   __________
            Std. Dev. phi  (pitch) degrees:   __________
            Std. Dev. kappa  (yaw) degrees:   __________
               Use these values at run time? (1=yes, 0=no)
            AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
                         (OR <Ctrl-C> TO CANCEL)

       The INITIAL values for (XC,YC,ZC) are expressed in standard (e.g.  UTM)  coordinates,  and
       represent an approximation for the location of the camera at the time of exposure.

                      X: East aircraft position;

                      Y: North aircraft position;

                      Z: Flight altitude above sea level

       The  INITIAL  values  for  (omega,phi,kappa)  are  expressed  in degrees, and represent an
       approximation for the cameras attitude  at the time of exposure.

                      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  degree  for  clockwise  turn  and -90 degree for a
                     counterclockwise turn.

       The standard deviations for (XC,YC,ZC) are expressed in meters, and are used as  a  priori
       values  for  the  standard  deviations  used  in  computation  of  the ortho rectification
       parameters.

       The standard deviations for (omega,phi,kappa) are expressed in degrees, and are used as  a
       priori  values  for the standard deviations used in computation of the ortho rectification
       parameters.

       If Use these values at run time? (1=yes, 0=no) is set to 0, the values in  this  menu  are
       not used.

SEE ALSO

        i.ortho.photo, i.photo.camera, i.photo.2image, i.photo.2target, i.photo.rectify

AUTHOR

       Mike Baba,  DBA Systems, Inc.

       Last changed: $Date: 2010-12-22 02:05:10 -0800 (Wed, 22 Dec 2010) $

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       © 2003-2013 GRASS Development Team