Methods of 3D Art
(c) 1993 donavaN kienenbergeR

	The ability of viewing images in three dimension has been around for many years.  It has grown, branching out  into many different art and technological mediums.  It is a unique form of art that has yet to reach its full potential.
	The theory of  viewing  images in three dimensions  has been around since at least the second century A.D.  Galen, a Greek physician was the first to address these theories in writing.  
	The first  scientific study of  three dimensional viewing  occured in 1833.  Sir Charles Weatstone created a mirrored device for viewing hand drawn images in three dimensions.  He published his findings in 1838.  In 1844 an easy to use stereoscopic viewer was invented and shortly after many homes had viewers for viewing stereoscopic photographs.  The fasination hasn't stopped yet.
	The basic building block of creating a three dimensional image is two different visual perspectives of the same image.  To see in depth we use both of our eyes.  Each one creates a different perspective for our brains to interpret and extract depth information.  Thats why if you were to cover up one eye for a day, and walk around, you would find after a while that it is very difficult to judge distances between objects that are nearer and far from yourself.  
	There are a variety of methods used to give our minds the information needed to experence depth.  The most used depth methods are shading and perspective drawing.  These methods however do not give us true depth preception.  Our minds have learned to associate certain properties of our visual environment with depth in art.  
	Shading in a two dimensional drawing causes us to associate darker, or hazy areas with visual areas that farther away in depth, or are unlighted due to the shadow cast by an object that has depth to it.  This play of light and dark give us information we associate with true depth, but not the preception of depth.

	The perspective of a two dimensional drawing also cues our mind to associate the information with depth.  As an object get farther away from our person, it visually shrinks in size.  Larger objects are assumed to be closer, and smaller object are considered to be farther away.  Parallel lines that would normally never touch merge together far off in the depths of distance.  
	Both of these properties and their close association with depth preception only give us clues to how far away one object might be from another.  We can still pick up these clues using one eye and seeing only one perspective.  True visual depth must come from images using two separate perspectives.
	The first method used to create true three dimensional perspective depth information from two dimensional images were called stereograms or stereo photographs.  The technique involves creating two, two dimensional images  from slightly different perspectives and lay them side by side.  The viewer then crosses his eyes until both images merged into one image, and lets their eyes focus until that image becomes clear giving them a single image perceived with depth.  
	The left and right eyes are each seeing both perspectives when they cross.  This causes the crossed eyes to see a double image  of what they were seeing before.  Two of those perspectives from the double image overlap,  merging together to form an image composed of the two needed perspectives to see the image in depth.

      (Both eyes)
    L         R
    O         O         1.  The viewer looks at the left and right
                           images with both eyes.
(Left eye)  (Right eye)
L    R         L    R
O ->( )       ( )<- O   2.  The viewer crosses their eyes, causing 
                           the mind to split each eyes view into a
                           separate image, creating double images.
L        RL         R 
O -->   (())    <-- O   3.  The two inner left and right images begin
                           to merge into one.
L        R&L        R
O        (O)        O   4.  The viewer focuses on the single image in
                           the middle until it come into clear focus
                           giving an image with depth.


                     IIIIIIIIIIIIIII     IIIIIIIIIIIIIII
                     H   ( )   \|/ H     H ( )  \|/    H
                     H  (   )  -O- H     H(   ) -O-    H     
                     H (     ) /|\ H     H     )/|\    H
                     H==(   )======H     H(   )========H
                     H----|----@---H     H--|----@-----H
                     H   /|\@ \|/@ H     H /|\ @\|/ @  H
                     H     \|/  \|/H     H    \|/  \|/ H
                     III|IIIIIII|III     III|IIIIIII|III
                   Cross  eyed  stereo  Cross eyed stereo

	Stereogram images can also viewed with a pair of prismatic gasses that help the viewer to cross images to view the image in depth, or with two tubes that cut out the outer left and right images that could distract the viewer.
	There is also a similar method to viewing stereograms called wide-eyed viewing.  This method works in a similar fashion to the cross-eyed method, only it gives the viewer a reversed or inverted image.  It is a bit more dificult to learn.  The viewer has to bring the image right up to their face and let their eyes relax until the image goes out of focus, then slowly pull the image back from their face until the to perspectives line up.  With wide-eye viewing it's harder to get the image in focus.  Many of the older prismatic glasses used this method.
	Artist such as Rene Magritte and Salvador Dali also created painted images in three dimensions using the stereogram technique.  Magrette's "Man with a newspaper" was painted as a multiple stereogram.  It is layered out in a window box fashion and contains four images of the same room each painted in a slightly different perspective.  The top left image is the only perspective that contains a man reading a newspaper.  When viewed stereographically the man appears as a ghostly image sitting at a table.  
	The painting can be viewed right side up, sideways, diagonally and upside down and the viewer will still see the image in a three dimensional perspective each time.  This is a very hard effect to achieve considering that the image is hand painted.  
	 Dali's interest in stereograms began when he came across some images by Gerard Dou.  Gerard was a pupil of Rembrant, who had drawn several views of the same scene at different times.  when Dali saw them he had noticed that the views had several stereographic components.  He later began painting stereograms himself.
	Dali painted a variety of stereograms, "The chair" from 1977 depicts a hand painting a lady who sits watching a large chair that floats on the horizon.  The chair is painted from a different angle than the rest of the objects of the painting making it the most unique object in the painting.  
	"The Christ of Gala" 1978 was also painted stereographically.  It's an image of Christ on the cross laying flat on a horizon.  I have heard rumors that Dali's "crucifixion" 1954 may also have been painted in three dimensions, however I have not been able to verify that, and it may have just been confused with "The Christ of Gala".  
	The best of his work that I have seen is entitled "Dali's hand raising a gold veil in the shape of a cloud to show Gala the naked drawn far beyond the sun (Homage to Claude Lorrain)" 1977.  It is an amazing painting to view in depth.  Several Greek architectural buildings surround a bay that disappears into the horizon.  At the horizon is a sunset and standing behind the sun is a nude Gala being unveiled.  Several people stand at the base of the shore/dock staring up at the Gala.  Its view of depth is amazing and adds a lot to the image.  Ship and building receding in the depth draw the viewers eyes straight to the sunset and the sunset brings the viewer's eyes to the Gala.  
	Dali has done many more images in three dimensions such as: "Odalisque cyberne tique", "A la recherchede la quatrieme dimension", "Sardane pentagonale", "Les Menines", "Soleil",  and "La naissance de Venus".  He was also working on one called "Dali from the back painting Gala from the back eternalized by six virtual corneas provisionally reflected by six mirrors," when he died and it was never finished.   
	The process and methods used by these artists for creating three dimensional images has grown.  Artists are no longer stuck with painting on canvases, or photographs and cameras.  Realistic looking imaginary images can be created on computers using raytracing, rendering or graphic programs.  
	A raytraced image is created by defining objects such as spheres, boxes, triangles, etc.  .  .  mathematically on an x, y, z coordinate plane.  These objects are then ran through a program that calculates how light rays will bounce off the object which creates an image.  Since the objects are in x, y, z three dimensional coordinates, all the artist need do in order to create a second perspective is to move the "camera" (or where the objects are being viewed from) to a different location and run the program again.  The artist then has two imaginary  computer generated images which can be viewed as stereogram.
 
	There are two other methods that are variations on the stereographic methods of creating three dimensional images.  One is called Single Image Random Dot Stereograms (SIRDS).  It uses a mixed diffused pattern created by a mathematical equation to hide the left and right images in one image.  These are also created on computers that let the artist create the separate layered images that make up the various depth levels of the SIRDS and the computer program combines the layers into a single image that can be viewed cross eyed.  The other is called Dual Image Random Dot Stereograms which creates a defused pattern but creates the two images separately like standard stereograms.
 
	Another common variation for viewing three dimensional images involves the use of red-blue or red-green glasses for viewing.  This method takes the work out of viewing the images, but the image isn't as sharp as when viewed cross-eyed.  The two different perspectives are recorded in different colors of the image, and the glasses are used to separate the overlaid images, one for each eye.  
	It works by taking the two perspectives and placing the right perspective in blue and greens channels of the image and the left perspective in the red channel.  
	When  the image is seen through  red-blue/green glasses the blue or green filter paper stops the blue information coming from the image and only lets that eye see the red color or left perspective.  The process is similar for the red filter and that eye only seeing the  right perspective information.  Each eye is forced to see only  one of the perspectives and it re-interprets that information back into judgment of depth.
	Normal stereograms can be changed into red-blue/green stereograms by using computer programs.  An artist can scan in each image of the stereogram and place it on a computer, than manipulate the image in a computer program to place the correct perspectives in the correct color channels.
 
	Other methods of  creating three dimensional images involve using moving displays, or very high cost equipment.   
	Holography is another form of  creating images in three dimensions.  Holograms produce exact three dimensional duplicates of the original object from light.  Even if they are viewed under a microscope, detail that was in the original can be seen.  Holograms store thousands of perspectives of the same image onto one piece of photo sensitive film, allowing the viewer to see the image from a variety of perspectives.  
	For most artists holography just doesn't have the flexibility or affordably  to be a usable medium.  Holograms require a lot of equipment and are very expensive to make.  They are created by using a laser and a variety of optical equipment.  They also requite very dense film that is specifically sensitive to the color of the laser.  During the exposing of the holographic film, if the object of the moves at all, the hologram will come out as a blur.  To re- view a full holographic image the viewer has to re-illuminate the hologram with laser light.  Other methods can be used to view holograms, but the complete image is not shown in those types of holograms.
	There is a method called the Pulfitch effect that can be used to view normal TV and some specially designed computer games in three dimensions.  A viewer covers one eye with the lens of a dark pair of sunglasses and leaves the other uncovered when watching a moving image on a television, or movie screen.  The image has to be panning/moving from the left to right or vice-versa for the viewer to pick up the three dimensional effect.   
	Having one eye view the image through a darkened frame of the sunglasses causes the brain to take longer processing the information that eye is taking in.  Because of the delay in processing the image information, each eye is seeing the movie/television image from a slightly different perspective, causing the viewer to see the moving image with depth. This is the same method FOX TV will be using for its May 8th Broadcast.

 ________
|        |
| ---> | If the image on the screen is moving from left to right 
|______| the right eye must be covered to best see the image in depth.
 screen
 ________
|        |
| <--- | If the image on the screen is moving from right to left 
|______| the left eye must be covered to best see the image in depth.
 screen

	This method can be used by artists in computer games that constantly scroll on the screen,  or in artistic videos/films specifically designed for this effect.  
	The only drawback to this method of creating a three dimensional image is that the eye covered by the sunglasses can sometimes become irritated due to the strain caused by the eyes' attempt to process the difference in the viewed information.

	There are specialized electronic glasses called active stereo glasses that produce moving three dimensional images that work with some specially designed television systems and computer systems.  There are two types: polarized and active LCD or shutter.  
	 Polarized glasses are mainly used for film.  They work by having two projectors placed side by side, each containing film shot from different perspectives.  The projectors each have a polarized lens placed on them at ninety degree angles to each other and are projected onto a screen that does not depolarize the light.  The viewer wears glasses that have similar polarizers on them so that one of the projected images is blocked from each eye, giving each eye a separate perspective.
	Shutter glasses are mainly used with video, or television.  Television is displayed at sixty half-frames per second on a TV screen.  A TV alternates by displaying one frame on all the even lines of the TV then one frame on all the odd line of the TV screen.  So in reality you're only seeing thirty mixed full frames per second or sixty half frames per second.  
	The shutter glasses work by synchronizing with the TV and have little LCD shutters that are built into the glasses that turn off and on with the video sixty times per second.  All the even lines displayed on the TV contain one perspective, and all the odd lines contain the other perspective.  The result is that the left eye is darkened whenever the right eye image is on the screen and visa versa.

	These are most of the common methods used in viewing art in true three dimensional form.  Other systems have been created that are either mixtures or variations on these methods, or are obscure and well guarded.  (or I just may have missed one :-)  Three dimensional art is one of those things that never quite seemed to catch on as well as it should have.  It has a lot of potential and possibilities.  Perhaps with the ease of use that the computer age brought with it, more people will create images showing a true depth perception in them.  Only time will tell.


                    \   \ E                  \   \ E
                      \  \    n               \   \   n
                       \  \      d             \  \     d
                         \  \_____              \  \_____
                           \_______              \_______



References

Kienenberger, D.  (1993).  "Blobo,  3D Blobo"
Kienenberger, D.  (1993).  "Crystal Globe"
Hewes,M.  (1993).  <nitram@te~labs.com> "Wide Eye Stereo".
Watters, M.  (1993).  <watters@genetics.washington.edu> "stereoscopic glasses" 
Watson,Henry.  (1993).  <watson@sfu.ca> "sirds"
Lurker, K.  (1993).  <kluker@alexandria.lib.utah.edu> "Dali:Fine art in stereo"
Kleein, A.  (1993).  <klein@stereo.stgt.sub.org> "Dali:Fine art in stereo"
Girling, A.  (1990).  Stereoscopic Drawing.  Atlantes Litho Ltd.
Hayes, R.M.  (1989).  3-D Movies.  McFarland & Co.  Inc.
Tate Gallery, the.  (1980).  Salvador Dali.  The Tate Gallery Dep.
Dali, S.  (1978).  "The Christ of Gala"
Larkin, D.  (1972) Magritte.  Ballantine Books
"3dplanes.gif".  SIRDS.  furmint.nectar.cs.cmu.edu.
"planes.gif".  SIRDS.  furmint.nectar.cs.cmu.edu.