Recently I had a client express uncertainty regarding the term “3D medical animation” on my company website. Did the 3D animation I produced have to be viewed with special “3D” glasses? I assured him that wasn’t the case. “Well then”, he asked, “how does the “3D” part of it work?” And therein lies a confusing aspect of the term “3D Medical Animation, or “3D animation” in general, for the term refers to animation created with the use of virtual 3D objects, and not a “3D viewing experience”, as we have recently become accustomed to seeing at the movies. I’m hoping that today’s post will shed a little light on the difference.
A LITTLE ANIMATION HISTORY
In understanding what modern 3D animation is, it’s helpful to look at a bit of the history of animation. Historians have traced man’s desire to graphically depict motion as far back as cave paintings from the paleolithic era, where, for example, horses were pictured with multiple sets of legs in different positons to impart the idea of motion. There are many similar examples over the millenia since, but one of the earliest devices to successfully give the illusion of motion was the Zoetrope. The first known instance of this device was in China in 180 AD, but the “modern” appearance dates to 1834. The Zoetrope consisted of a wheel, lined on its inner surface with a series of drawings, each drawing portraying an animal or characters, with slight differences in the positon of the subjects from one drawing to the next. The wheel had a series of vertical slits. Each slit permitted the viewer to see just one of the images. When the wheel was rotated, the images, as viewed in sequence through the slits, gave the illusion of motion. The number of drawings that could be placed in the Zoetrope was limited to a dozen or so, so while the effect was mesmerizing to the viewers of the time, there was limited opportunity to tell any kind of a story with the animation, and it remained just a novelty.
ANIMATION GOES TO THE MOVIES
At the beginning of the Twentieth Century, animation made a huge leap forward when drawings could be photographed onto motion picture film, one drawing per frame of film, and then played back at 24 frames per second. Suddenly, there was no limit to how long an animation could be, and the creative possibilities for story telling were endless. The first known example of an animated motion picture was produced by J. Stuart Blackton in 1906. Titled “Humorous Phases of Funny Faces”, it depicted what appeared to be a cartoonist drawing faces on a chalkboard, with the faces coming to life with movement.
Humorous Phases of Funny Faces – J. Blackton 1906
From that point forward, animated motion pictures evolved rapidly. Favorite characters were born - Krazy Kat, Betty Boop, and Mickey Mouse. Sound was added; Argentinian Quirino Cristiani‘s 1931 production of “Peludopolis“ was the first to use synchronized sound. Color was added; Walt Disney won an Academy Award for ”Flowers and Trees” (1932), the first animation to use full, three-color Technicolor. Cartoons a few minutes in length gave way to feature-length animated motion pictures. Disney’s “Snow White” is easily the best known, and most successful, of the early features, but there were at least 8 feature-length animated pictures produced internationally prior to “Snow White” (none of these early features survive today). “Snow White” was also the first animated feature to use “cel animation”. In the cel technique, pictures are drawn using colored ink onto individual sheets of transparent celluloid (hence the term “cel”). The cel technique provided several major advantages; backgrounds and non moving objects in the foreground of a scene could be drawn on separate cels, as could the moving objects or characters in a scene. In this way the same background cell could be used repeatedly from one frame to the next. This saved an enormous amount of time in producing the animation, and eliminated the “jittery” characteristic of earlier animations, in which the entire scene, backgrounds, characters and all, had to be completely redrawn in each frame.
As well, the quality of artists creating animations saw steady improvement as the years went by. Again, Walt Disney was one of the first to pioneer the hiring of top-notch artists for his studio, providing them with ongoing training in the latest animation techniques. Eventually, Walt formed the California Institute of the Arts (CalArts), in Valencia, as an institution for the training of animation artists.
“MOVING PERSPECTIVE” AND THE MULTIPLANE CAMERA
The net result of all of these innovations was a steady improvement in the look and feel of animated productions (whether they be features or shorts). But prior to the computer age, there was an essential limitation in animation that no amount of artistic talent could overcome, and that was the fact that animation was a two-dimensional medium. It was very difficult, if not impossible, to convey a feeling of moving perspective in an animation. An example of moving perspective can be seen as you drive your car along a highway, surrounded by forests in the foreground, and hills and mountains in the background. As you view the scene from your moving car, the trees closest to you have an appearance of moving much more rapidly than trees in the background; at the same time, the hills move by at a quicker pace than the mountains behind them.
2D moving perspective – objects all move at the same speed irrespective of distance from the viewer
3D Moving Perspective – note how the apparent speed of the 3D objects varies with their distance from the viewer
This type of relative movement is extremely complex when trying to draw all of these elements one frame at a time, even with the cel technique. Walt Disney understood this limitation, and, in an attempt to overcome it, ever the innovator, he invented the “multiplane camera”. The multiplane camera consisted of a device that resembled a bookshelf (see figure 1), capable of housing 4 cel paintings inserted like shelves into the housing. The motion picture camera was attached at the top of the housing, and aimed downward through the paintings. Typically, foreground elements or characters were painted onto the top shelf or shelves, while deeper background elements occupied the lower shelves, with the deepest elements of all on the bottom shelf. As the animation was filmed, the camera could be moved (or “panned”) from side to side at the top of the housing. This would provide an illusion of moving perspective – elements on each painting would appear to be moving across the scene at different speeds. Foreground elements on upper paintings would appear to move more rapidly than background elements on the bottom. Walt first used this technique on “Snow White”, and for years afterward, the multiplane camera set the standard for “3 dimensionality” in animated films.
But the 3D effect created with the multiplane camera was just that – an effect. It permitted variable movement on 4 different planes within the animated scene. It did not capture the true experience of moving perspective, in which we see an almost infinite variation in movement of objects as we pass by a scene. Let’s go back to our drive by the forest and mountains. As we cruise along, the mountains in the background appear to move at a slower speed that the trees in the foreground, but each tree is also at a different distance from us. Therefore, our perception is that each tree moves at a slightly different speed as well. Even the individual branches on a particular tree are at varying distances, so that branches closer to us appear to be moving more rapidly than those further away. The needles on an individual branch are subject to the same phenomenon, and on and on. Thus, the infinite complexity of moving perspective.
THE COMPUTER AGE AND TRUE 3D
With the advent of the computer, it became possible to create “3D” objects in the virtual space of the computer screen. Unlike traditional 2D animation drawings, which can have height and width but not depth, these objects truly have three dimensions, and once created, can be manipulated on the screen just like an apple can be manipulated in your hand; the 3D object can be rotated, flipped top to bottom, and any side of it viewed from any angle. The manipulation of 3D objects in virtual space provides tremendous advantages over 2D when it comes to conveying information about an object to the viewer This comes in especially handy in technical or scientific animation, such as the 3D medical animation I have specialized in for the past decade. Take a look at 3D Medical Animation #1. This is an animation depicting the male pelvic anatomy. Each anatomical object was “built” as a 3D object, hence we can view these objects from any angle, and as the camera chnages perspective, the relationships of the structures are readily revealed. In this segment, the anatomical structures are viewed, first, from the front, then from the side, and finally, from above.
3D Medical Animation 1 – Male Pelvic Anatomy
3D Medical Animation #2 is another example; in this case, a newborn baby with a “nuchal” umbilical cord. Note how readily the relationship of the umbilical cord to the baby can be discerned as a result of the ability to view the baby from all sides.
3D Medical Animation 2 – Nuchal Umbilical Cord
A scene built in 3D space can be populated with a whole group of 3D objects, all placed at different distances from the viewer, and all moving at different speeds with respect to each other as well as the viewer. Hence, a true experience of “moving perspective” can be achieved. The complex mathematical calculations involved in generating such a “3D” scene are taken care of by the big brain of the computer.
NOT ANIMATION IN 3D, BUT 3D ANIMATION…
So when animators use the term “3D animation”, we are generally not referring to a “3D viewing experience”, such as “Toy Story 3 in 3D”, where one feels as though the objects on the screen are jumping out at us.. We are, instead, referring to the manner in which the animation has been created, using virtual 3D objects and manipulating them in a virtual 3D universe, rather than drawing 2D images on paper or celluloid. In other words, it is not necessary to wear special glasses to view 3D Animation, but it is necessary to don them in order to have a 3D viewing experience at the movies (or increasingly, at home on the big screen).
It may well be that in the not too distant future, all animated productions, whether for pleasure or for knowledge, will be presented as a “3D viewing experience”. I’m certain the time will come when we will be able to throw away the 3D glasses altogether, and enjoy a true 3D holographic production. For the time being, anyway, the “3D viewing experience” will be confined to the movie houses and home entertainment rooms, and my clients (and jurors) will not be required to wear special glasses to view 3D medical animation at trial. Stay tuned…