3D Theory





3D / Anaglyph/Stereoscopic Technology

Acknowledgements to Michael Robins of the Johannesburg Centre of the Astronomical Society of Southern Africa

for the content on this page extracted from a
Power Point Presentation that he delivers.





How does 3D work?




Most humans/animals use what is known as binocular vision to perceive depth and see the world in 3D. The binocular vision system relies on the fact that we have two eyes, which are approximately 75 mm apart. This separation causes each eye to see the world from a slightly different perspective. The brain fuses these two views together. It understands the differences and uses them to calculate distance creating our sense of depth and ability to gauge distance.

A simple way to understand this principle is to hold your thumb up at arms length and close one eye. Then try closing the other eye. As you switch between open eyes you should see your thumb "jumping" back and forth against the background.







By no means is the projection/viewing of 3D images new.

In 280 A.D., Euclid recognized that depth perception is obtained when each eye simultaneously receives one of two dissimilar images of the same object.

In 1584 Leonado da Vinci studied the perception of depth.

Around the year 1600, Giovanni Battista della Porta produced the first artificial 3-D drawing based on Euclid's notions.

This was followed in 1611 when Kepler's Dioptrice was published which included a detailed description of the projection theory of human stereo vision.

It was Sir Charles Wheatstone who in 1833 first came up with the idea of presenting slightly different images to the two eyes using a device he called a reflecting mirror stereoscope.



The invention of the Brewster Stereoscope by the Scottish scientist Sir David Brewster in 1849 provided a template for all later stereoscopes.

Around 1860, Oliver Wendell Holmes invented the "American stereoscope“

Stereo photography peaked around the turn of the century and went out of fashion as movies increased in popularity. In 1939 William Gruber saw a way to make use of the newly invented flexible 35 mm film by Kodak and teamed up with Harold Graves to form the View-Master company. These toys first became available during the 1940's.



Stereo pairs



Typical stereo pair images are two separate images of the same object taken a few centimetres apart. In this method, the two images are not interlaced but rather presented side by side (left eye image on left and right eye image on right). The images are directly viewable using parallel "free-viewing" glasses which allow each eye to only see its corresponding image.





Colour filter glasses


Colour filter glasses is another method of viewing 3D images or movies. The system works by feeding different images into your eyes. The different colour filters allow only one of the images to enter each eye, and your brain does the rest. There are a number of colour filter systems: Red/Cyan, Red/Blue and Red/Green.





Polarizing glasses



This method is more commonly used in today's 3D movie projections. The audience must wear special glasses which have two polarizing lenses which have their polarization directions adjusted to be 90 degrees different. This makes it possible that left eye sees it's picture without problems but everything meant to right eye (sent out at different polarization) seems to be black. Same principal applies to right eye.





LCD shutter glass method


In the LCD shutter glass 3D display, the left and right images are alternated rapidly on the monitor screen. When the viewer looks at the screen through shuttering eyewear, each shutter is synchronized to exclude the unwanted image and transmit the wanted image. Thus each eye sees only its appropriate perspective view. The left eye sees only the left view, and the right eye only the right view.




How is this all done



One needs to take two photos of the same scene, with the cameras being displaced by a defined distance.

It is important to ensure that the camera axis between the first photo and the next remain parallel to one another and that no up/down movement takes place.

The distance between the two parallel axis's is known as the stereo base.

B = P(LN/L-N) (1/F - (L+N)/2LN)


B = Stereo Base (distance between the camera optical axes)

P = Parallax aimed for, in mm on the film

L = Largest distance from the camera lens

N = Nearest distance from the camera lens

F = Focal length of the lens


L-N = T = the front to back thickness of the subject.

With a bit of luck it is also the depth of field of the image, but does not have to be, especially at macro and telephoto distances where a big depth of field is hard to achieve.









Stereo and the Moon




Stereo photo of the moon, published in 1897 by T. W. Ingersoll, photographed by Prof. Rutherford, BW anaglyph. As with other high quality moon stereos, this was taken using liberation, the slight wobbling of the moon on its axis.




Stereo and the Apollo Missions



The Apollo 14 landing site is located on the rugged Fra Mauro Highlands south of the crater Copernicus. Topographic relief across the scene is ~500 meters.

These views (Taken with a Hasselblad camera) show an area 24 km across from top to bottom. North is to the top.

35-mm Lunar Surface Close-up Stereoscopic Camera. This camera was designed for the highest possible resolution (80 µm) of a 3-inch square area with flash illumination and fixed distance. Photography was accomplished by holding the camera on a walking stick against the object to be photographed.


Apollo 11 stereo view showing a clump of lunar surface powder, with various small pieces of different colour. (20 July 1969)






Stereo and the Mars Exploration Missions



Mars Reconnaissance Orbiter (MRO)

The High Resolution Imaging Science Experiment (HiRise) camera is a 0.5 m reflecting telescope, the largest ever carried on a deep space mission, and has a resolution of 1 micro radian (µrad), or 0.3 m from an altitude of 300 km.







Spirit and Opportunity

To date this is most probably the mission that has captured the largest number of stereo photographs of any NASA space program.

Hazcams (Hazard Avoidance Cameras)

Two Engineering Navcams (Navigation Cameras)

Two Science Pancams (Panoramic Cameras)





The Panoramic Camera (Pancam)

Pancam is a high-resolution colour stereo pair of CCD cameras used to image the surface and sky of Mars.

The Pancam Mast Assembly (PMA) allows the cameras to rotate a full 360° to obtain a panoramic view of the Martian landscape. The camera bar itself can swing up or down through 180° of elevation.

The Pancam cameras are small enough to fit in the palm of your hand (270 grams), but can generate panoramic image mosaics as large as 4,000 pixels high and 24,000 pixels around.



Stereo in the Modern World (NASA's Idea)



STEREO is an acronym for Solar TErrestrial RElations Observatory. This mission employs two nearly identical observatories to provide the first-ever, 3-D stereoscopic images to study the nature of coronal mass ejections (CMEs).

The STEREO mission offers a totally new perspective on solar eruptions by imaging coronal mass ejections and background events from two nearly identical observatories simultaneously. To obtain unique views of the sun, the one observatory is placed ahead of Earth in its orbit and the other behind.







Stereo and the Hubble Missions


This scientific visualization creates a three-dimensional virtual tour of several dark pillars of cool gas in the Carina Nebula. The stars and nebula layers from Hubble's two-dimensional image have been separated using both scientific knowledge and artistic license to create the depth in the picture. Of note, the relative distances between stars and the nebula have been greatly compressed.

Note: This is not a true stereo picture




Other 3D Images



The Sun




The Moon  





The Moon  





The Innes Telescope is a 26,5 inch refractor telescope on the grounds of SAASTA ( South African Agency for Science and Technology Advancement in Johannesburg  





Another view of the Innes Telescope  




A Martian Landscape  

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