Provided by: grass-doc_8.3.0-1_all 
NAME
i.ortho.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.ortho.init
i.ortho.init --help
i.ortho.init [-rp] group=name [xc=float] [yc=float] [zc=float] [xc_sd=float]
[yc_sd=float] [zc_sd=float] [omega=float] [phi=float] [kappa=float]
[omega_sd=float] [phi_sd=float] [kappa_sd=float] [--help] [--verbose] [--quiet]
[--ui]
Flags:
-r
Use initial values at run time
-p
Print initial values
--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
xc=float
Initial Camera Exposure X-coordinate
yc=float
Initial Camera Exposure Y-coordinate
zc=float
Initial Camera Exposure Z-coordinate
xc_sd=float
Apriori X-coordinate standard deviation
yc_sd=float
Apriori Y-coordinate standard deviation
zc_sd=float
Apriori Z-coordinate standard deviation
omega=float
Initial Camera Omega (pitch) degrees
phi=float
Initial Camera Phi (roll) degrees
kappa=float
Initial Camera Kappa (yaw) degrees
omega_sd=float
Apriori Omega (pitch) standard deviation
phi_sd=float
Apriori Phi (roll) standard deviation
kappa_sd=float
Apriori Kappa (yaw) standard deviation
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.ortho.init (menu 6) is only required when rectifying a tilted or oblique
aerial photo.
i.ortho.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 i.photo.2target.
The following menu is displayed:
Please provide the following information
INITIAL XC: Meters __________
INITIAL YC: Meters __________
INITIAL ZC: Meters __________
INITIAL omega (pitch) degrees: __________
INITIAL phi (roll) degrees: __________
INITIAL kappa (yaw) degrees: __________
Standard Deviation XC: Meters __________
Standard Deviation YC: Meters __________
Standard Deviation ZC: Meters __________
Std. Dev. omega (pitch) degrees: __________
Std. Dev. phi (roll) 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 (pitch): Raising or lowering of the aircraft’s front (turning around the
wings’ axis);
• Phi (roll): Raising or lowering of the wings (turning around the aircraft’s 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.
If ground control points are available, the INITIAL values are iteratively corrected. This
is particularl useful when the INITIAL values are rather rough estimates.
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. Higher values improve the refinement of the initial camera exposure. As a rule
of thumb, 5% of the estimated target extents should be used.
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. As a rule of thumb, 2 degrees should be used.
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.2image, i.photo.2target, i.ortho.elev, i.ortho.camera,
i.ortho.transform, i.photo.rectify
AUTHOR
Mike Baba, DBA Systems, Inc.
SOURCE CODE
Available at: i.ortho.init source code (history)
Accessed: Tuesday Jun 27 11:14:21 2023
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