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### PERSPECTIVE_PROJECT3D

PERSPECTIVE_PROJECT3D

## Name

PERSPECTIVE_PROJECT3D

## Purpose

This function will perform a perspective projection of a three-
dimensional point defined in homogenous coordinates onto a two-
dimensional "focal plane" as if being acquired by a camera
located in 3-space with a specified focal length, pixel size,
and "look at" position.

GENERAL.

## Calling Sequence

result = PERSPECTIVE_PROJECT3D( point, \$
cameraPosition, \$
focalLength, \$
pixelSize, \$
lookatPosition, \$
OBSERVER_UP=observerUp )

## Inputs

point
A vector containing the three-dimensional point to be projected in
homogenous coordinates [x,y,z,1].
cameraPosition
A vector containing the three-dimensional point at which the camera
is located in 3-space. Ths point is defined in homogeneous coordinates.
focalLength
A scalar defining the focal length of camera's lens (while this value
serves as a scaling factor, keeping the units consistent with the pixel
size is required).
pixelSize
A scalar defining the pixel size of the camera (pixels are assumed to
be square) (while this value serves as a scaling factor, keeping the
units consistent with the focal length is required).
lookatPosition
A vector containing the three-dimensional point at which the camera is
staring in 3-space. This is only used to define the direction of gaze.
This point is defined in homogeneous coordinates.

## Keyword Parametrs

OBSERVER_UP
Set this keyword to a 4-element homogenous vector defining the up
direction of the observer (as if the observer is holding the camera).
The default value is [0,0,1,1] indicating up is in the positive z-
direction.
:ERROR CHECKING:
None.

None.

NORMALIZE
NORMH

## Modification History

Written by: Carl Salvaggio
January, 2012 Original code

## Disclaimer

This source code is provided "as is" and without warranties as to performance
or merchantability. The author and/or distributors of this source code may
have made statements about this source code. Any such statements do not
constitute warranties and shall not be relied on by the user in deciding
whether to use this source code.
This source code is provided without any express or implied warranties
whatsoever. Because of the diversity of conditions and hardware under which
this source code may be used, no warranty of fitness for a particular purpose
is offered. The user is advised to test the source code thoroughly before
relying on it. The user must assume the entire risk of using the source code.

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