PERSPECTIVE_PROJECT3D

Name

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.

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.

Side Effects

None.

Requires

NORMALIZE
NORMH

Modification History

Written by: Carl Salvaggio
January, 2012 Original code

Disclaimer

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relying on it. The user must assume the entire risk of using the source code.