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i.ortho.init(1) GRASS GIS User's Manual i.ortho.init(1)

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

imagery, orthorectify

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]

-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

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

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.

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

Mike Baba, DBA Systems, Inc.

Available at: i.ortho.init source code (history)

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© 2003-2021 GRASS Development Team, GRASS GIS 7.8.6 Reference Manual

GRASS 7.8.6

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