# i.ortho.init.1grass - Man Page

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*Â**[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 (roll) degrees

**phi**=*float*Initial Camera Phi (pitch) degrees

**kappa**=*float*Initial Camera Kappa (yaw) degrees

**omega_sd**=*float*Apriori Omega (roll) standard deviation

**phi_sd**=*float*Apriori Phi (pitch) 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 (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)

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 (roll): Raising or lowering of the wings (turning around the aircraft’s axis);
- Phi (pitch): Raising or lowering of the aircraft’s front (turning around the wings’ 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.

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.

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.

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)

Main index | Imagery index | Topics index | Keywords index | Graphical index | Full index

Â© 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual