i.ortho.init(1grass) GRASS GIS User's Manual i.ortho.init(1grass)
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 photo-
graphs can be truly vertical (nadir), or slightly tilted (less than 3
degree from the vertical). Usually aerial photos are tilted to some de-
gree. We refer to the term vertical photograph up to a tilt of 3 de-
gree.
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 en-
tries include: the (XC,YC,ZC) standard (e.g. UTM) approximate coordi-
nates of the camera exposure station; initial roll, pitch, and yaw an-
gles (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 cam-
era 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 ex-
posure.
• 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 itera-
tively 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 re-
finement 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.or-
tho.camera, i.ortho.transform, i.photo.rectify
AUTHOR
Mike Baba, DBA Systems, Inc.
SOURCE CODE
Available at: i.ortho.init source code (history)
Accessed: unknown
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GRASS 7.8.7 i.ortho.init(1grass)
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