Stereoscopic Images Binocular vision enables us to measure depth using eye convergence and stereoscopic vision. Eye convergence is a measure of the angle between the eyes’ optical axes when fixating upon some point. Stereopsis describes the process of obtaining two distinct views of an object when viewed with two eyes.

Stereoscopic vision describes the three dimensional sensation of depth associated when seeing with two eyes.

Optical Angle Optical Angle (eye convergence) : The optical angle Θ1 of object 1 is larger than the optical angle Θ2 of object 2. So that we sense object 2 is closer. The distance is measure using optical angle. Left eye Right eye Object 2 Object 1

Visual Angle Visual Angle: The visual angle is the angle a viewed object subtends at the eye The size of object is justified based on visual angle. The visual angle Θ1 of object 1 is smaller than the visual angle Θ2 of object 2. So that we sense object 1 is smaller. Object 2 Object 1

Parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight .

This animation is an example of parallax This animation is an example of parallax. As the viewpoint moves side to side, the objects in the distance appear to move more slowly than the objects close to the camera.

Parallax vs. Disparity Binocular Retinal Disparity describes the position shift of an object between two views. Parallax and Disparity are actually the same terms. Parallax is generally used for screen display while disparity is used for retinal. Stereo vision is created based on the principal of parallax.

How to make stereo images? The distance between two pupils of the eyes is around 6.3cm~7.0cm. You need to take pictures twice by shifting a disparity. Disparity = 3D object distance ÷ 50 object right left disparity

Examples:

立體眼鏡

Shutter Glasses   Interlacing Page-Flipping

Interlacing

Page-Flipping

Perspective Projection

Stereo perspective projection (3.5) The left and right eyes are separated by Se

To compute the perspective projection of the box such that the left eye is gazing along the z-axiz, the x-coordinates are translated by –Se/2

To compute the perspective projection of the box such that the right eye is gazing along the z-axiz, the x-coordinates are translated by Se/2

example

x y z xpl ypl xpr ypr 5 40 0.58 1.67 2.75 -5 -1.67 -2.75 -0.58 50 0.5 1.43 2.36 -1.43 -2.36 -0.5