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<h2>NAME</h2>
<em><b>photo.init</b></em>
<H2>DESCRIPTION</H2>
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 <i>vertical photograph</i> 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.
<P>
<b>The use of <EM>photo.init</EM> (menu 6) is only required when rectifying a
tilted or oblique aerial photo.</b>
<P>
<EM>photo.init</EM> 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 <EM>a priori</EM> standard deviations for these
parameters. During the imagery program, 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 <EM><A
HREF="photo.2target.html">photo.2target</A></EM>.
<P>
The following menu is displayed:
<PRE>
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)
</PRE>
<P>
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.
<ul>
<li> X: East aircraft position;
<li> Y: North aircraft position;
<li> Z: Flight altitude above sea level
</ul>
<P>
The INITIAL values for (omega,phi,kappa) are expressed in degrees, and
represent an approximation for the cameras attitude at the time of
exposure.
<ul>
<li> Omega (roll): Raising or lowering of the wings (turning around the
aircraft's axis);
<li> Phi (pitch): Raising or lowering of the aircraft's front (turning
around the wings' axis);
<li> 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.
</ul>
<P>
The standard deviations for (XC,YC,ZC) are expressed in meters, and
are used as <EM>a priori</EM> values for the standard deviations used in
computation of the ortho rectification parameters.
<P>
The standard deviations for (omega,phi,kappa) are expressed in degrees, and
are used as <EM>a priori</EM> values for the standard deviations used in
computation of the ortho rectification parameters.
<P>
If <i>Use these values at run time? (1=yes, 0=no)</i> is set to 0, the
values in this menu are not used.
<H2>SEE ALSO</H2>
<EM><A HREF="i.ortho.photo.html">i.ortho.photo</A></EM>,
<EM><A HREF="photo.camera.html">photo.camera</A></EM>,
<EM><A HREF="photo.2image.html">photo.2image</A></EM>,
<EM><A HREF="photo.2target.html">photo.2target</A></EM>,
<EM><A HREF="photo.rectify.html">photo.rectify</A></EM>
<H2>AUTHOR</H2>
Mike Baba, DBA Systems, Inc.
<p><i>Last changed: $Date: 2006-09-22 16:57:14 +0200 (Fri, 22 Sep 2006) $</i>
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