Older technology has no way of displaying of displaying Stereoscopic Images without either Glasses (red/cyan anaglyph glasses) or making the user cross or diverge their vision or create random dot images. All techniques have their limitations to providing an immersive and easy experience.

Vergent Viewing Technique (Free Viewing)

Vergent refers to the ability of the viewer to either converge (cross-eyed at extreme) or diverge their vision of two adjacent images (Stereo Pairs) so the images will appear overlapped in their vision and consequently have depth calculated by their brain. This is actually the most accurate stereoscopic technique as it perfectly recreates the image. The large downsides is the need for the viewers to be skilled enough to train their eye muscles, image size limitation,  the extra ‘ghost’ images and the removal from the normal vision integration. If the image is intended to be viewed via divergent eye movement the images cannot be separated more than the pupil distance of the viewer as we can’t diverge our eyes more than parallel. If the image is intended to be viewed cross-eye the images can be slightly larger but the increasing size will cause eye strain in the viewer.

[examples]

This unsurprisingly is the original method of viewing stereoscopic images which first appeared soon after Photography was developed. Sir Charles Wheatstone was credited with creating the original stereoscope which consisted of lenses to enlarge and focus the images and a barrier to block the images from the wrong eye. There was a boom in stereoscopic images in the early 18th century and many of the images can be found online and viewed with a Convergent/Divergent technique.

[vintage examples]

These images can either be created by taking two different photographs or by manipulation of a 2D digital image or by 3D digital model creation and two different renders.

Random Dot Auto Stereography

Random Dot Stereography uses the same viewing technique as the Vergent Viewing above, the images however are completely different. These images are created by having a repeating pattern which when viewed using a vergent technique will align two sections of the pattern the brain will calculate there is no difference between the two patterns are produce a flat depth. If one of the patterns is distorted horizontally the brain will then produce depth perception based on the horizontal variations. A full greyscale image can be used to distort a pattern which will lead to depth creation when viewed.

[RAEZ examples]

Anaglyph Stereoscopy

Anaglyph is the last version which can be created on non-stereoscopic displays. This method requires the use of red/cyan glasses. This method relies on the different principals of light wavelengths. The two left and right images are overlayed togther in one image with left image appearing in the red channel and the right image appearing in the green/blue channel creating Cyan. Without glasses both overlays are visible with the offset images appearing with a red or cyan edge. With the glasses using the same colour filter the red image will pass through the red lens and the cyan light blocked by the lens for the Left eye. The Right eye filter will only let through the Cyan light only and block out the red which provides the two different images to the two eyes. This technique allows for full size images, and integration into the normal vision of the user creating much high immersion. The downsides is the requirement of glasses which may not be available and reduce immersion levels. Each eye being provided a different colour image also leads to binocular disparity with the brain struggling to comprehend the different coloured images.

[RAEZ examples]

Stereo (Greek root) – meaning: Solid
Scopy (Greek root) – meaning: View/Observer/Look At
Stereoscopy (Modern) – meaning: the viewing or appearance of objects in or as if in three-dimensions

Both the Greek roots lead the modern definition of ‘solid vision’ referring to perceived depth which we refer to as three-dimensional.

Human Visual Physiology – How we perceive the universe in 3D

The ability to perceive depth is a very simple concept. Human beings have two eyes which are fed a slightly different view of the world from their slightly different positions. The human visual cortex takes these two images combines the images (known as cyclopean vision) and compares the differences between the two views to create a depth perception. If a point (of an object) appears far apart in the vision from each eye then it must be close. If a point appears to be identical in both eyes then it must be far away. The ability of the brain to perform these calculations and how they are calculated still isn’t fully understood but the outcome is very powerful.

Human Visual Physiology Limitations

Stereoscopic vision seems to many people to be an infallible sense but in reality is very limited and error prone.

To have stereoscopic vision a Human requires both eyes to be focus (accommodate) and Look at (convergence) the same view and provide two near identical images to the brain. If one eye is not fully functional then no depth can be perceived. Even with perfect vision there are plenty of limitations. The human eyes see 95 degrees out and 60 degrees in which only leads to a 190 degree total view and a 120 view where the eyes overlap and are able to perceive Depth. The average distance between eyes in adults is 54-68mm and 10mm less for children. This distance between pupils allows depth perception to be calculated only to about 30 times this distance. Humans have fantastic depth perception within arms reach and reducing depth perception to about 30 meters beyond which all objects appear at the infinite flat plane.

There are many situations in the world where perfect Stereoscopic vision will fail to produce correct depth perception if at all. Both eyes can only judge depth based on differences supplied to both eyes. A solid colour object evenly lit will produce no depth in human vision and will appear invisible on the same coloured background. A repeating pattern can create stereo errors where the brain doesn’t know which pattern should be aligned correctly. Many vision scenes will have objects that do not provide a corresponding image on both eyes to be compared and depth calculated. A cube directly in front of a person will have the Left eye seeing the left edge of the cube and the right eye seeing the right side of the cube with neither eye seeing a corresponding image of that side to compare

Later years brought out the Graphic Designer aspects and I went onto Create a Set of Random Dot Auto Stereograms and learnt the basics of stereoscopy to start explaining to people how the human visual physiology allowed depth perception.

Years down the Track, I now run two Graphic Design Businesses, Teach Design at a couple of International Colleges,Completed a Degree in Biology and Computer Science, Completed a Masters in Anamorphic Stereopscopy, Create Stereoscopy Photography with a Stereo Camera and Create Stereoscopic Artwork through 3D Rendering.

So I’ll be showing viewers various Stereoscopic Work I have created Across the years, Explain some of the new technological advances and teach the principals of Stereoscopic Design and techniques.

Welcome to the RAEZ Stereoscopy site

Welcome and I hope you get some enjoyment and gain information from the content that will be discussed here, Wesley Lamont.