---
name: "photo.init"
section: "1grass"
platform: "linux"
package: "grass-doc"
version: "6.4.0~rc6+42329-3"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/photo.init"
---

# photo.init(1grass)

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

## NAME

**photo.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

**photo.init**\
 **photo.init help**\
 **photo.init group**=*name*  \[--**verbose**\]  \[--**quiet**\]

### Parameters:

- **group**=*name*

  Name of imagery group for ortho-rectification

## 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** *photo.init* (menu 6) is only required when rectifying a tilted or oblique aerial photo.

*photo.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, 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 *\<A* *HREF="photo.2target.html"\>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,* *photo.camera,* *photo.2image,* *photo.2target,* *photo.rectify*

## AUTHOR

Mike Baba,  DBA Systems, Inc.

*Last changed: $Date: 2008-10-22 11:59:36 +0200 (mer, 22 ott 2008) $*

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