.TH i.photo.init 1grass "" "GRASS 6.4.4" "Grass User's Manual"
.SH NAME
\fI\fBi.photo.init\fR\fR  - Interactively creates or modifies entries in a camera initial exposure station file for imagery group referenced by a sub-block.
.SH KEYWORDS
imagery, orthorectify
.SH SYNOPSIS
\fBi.photo.init\fR
.br
\fBi.photo.init help\fR
.br
\fBi.photo.init group\fR=\fIname\fR  [\-\-\fBverbose\fR]  [\-\-\fBquiet\fR] 
.SS Parameters:
.IP "\fBgroup\fR=\fIname\fR" 4m
.br
Name of imagery group for ortho-rectification
.PP
.SH 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 \fIvertical photograph\fR up to a tilt of 3 degree.
.br
Oblique aerial photographs are purposely taken with an
angle between 3 and 90 degree from the nadir direction.
.PP
\fBThe use of \fIi.photo.init\fR (menu 6) is only required when rectifying a
tilted or oblique aerial photo.\fR
.PP
\fIi.photo.init\fR 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 \fIa priori\fR standard deviations for these
parameters. During the imagery program, \fIi.photo.rectify\fR, 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 \fI<A
HREF="i.photo.2target.html">i.photo.2target\fR.
.PP
The following menu is displayed:
\fC
.DS
.br
        Please provide the following information
.br
.br
	INITIAL XC: Meters                __________
.br
	INITIAL YC: Meters                __________
.br
	INITIAL ZC: Meters                __________
.br
	INITIAL omega (roll) degrees:     __________
.br
	INITIAL phi  (pitch) degrees:     __________
.br
	INITIAL kappa  (yaw) degrees:     __________
.br
.br
	Standard Deviation XC: Meters     __________
.br
	Standard Deviation YC: Meters     __________
.br
	Standard Deviation ZC: Meters     __________
.br
	Std. Dev. omega (roll) degrees:   __________
.br
	Std. Dev. phi  (pitch) degrees:   __________
.br
	Std. Dev. kappa  (yaw) degrees:   __________
.br
.br
        Use these values at run time? (1=yes, 0=no)
.br
.br
     AFTER COMPLETING ALL ANSWERS, HIT <ESC> TO CONTINUE
.br
                  (OR <Ctrl-C> TO CANCEL)
.br
.DE
\fR
.PP
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.
.RS
.IP
 X: East aircraft position;
.IP
 Y: North aircraft position;
.IP
 Z: Flight altitude above sea level
.RE
.PP
The INITIAL values for (omega,phi,kappa) are expressed in degrees, and
represent an approximation for the cameras attitude  at the time of 
exposure. 
.RS
.IP
 Omega (roll): Raising or lowering of the wings (turning around the
aircraft's axis);
.IP
 Phi (pitch): Raising or lowering of the aircraft's front (turning
around the wings' axis);
.IP
 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.
.RE
.PP
The standard deviations for (XC,YC,ZC) are expressed in meters, and
are used as \fIa priori\fR values for the standard deviations used in 
computation of the ortho rectification parameters.
.PP
The standard deviations for (omega,phi,kappa) are expressed in degrees, and
are used as \fIa priori\fR values for the standard deviations used in 
computation of the ortho rectification parameters.
.PP
If \fIUse these values at run time? (1=yes, 0=no)\fR is set to 0, the
values in this menu are not used.
.SH SEE ALSO
\fI
i.ortho.photo,
i.photo.camera,
i.photo.2image,
i.photo.2target,
i.photo.rectify
\fR
.SH AUTHOR
Mike Baba,  DBA Systems, Inc.
.PP
\fILast changed: $Date: 2010-12-22 11:05:10 +0100 (Wed, 22 Dec 2010) $\fR
.PP
Full index
.PP
© 2003-2014 GRASS Development Team