Technical Field

This invention relates to apparatus and methods for obtaining three-dimensional images from two-dimensional images on either film or videotape.

Background Art

In the 1920's an optical illusion was discovered which has been referred to as the Pulfrich effect or illusion. In order to be elicited, it requires constant motion under very defined conditions. It is able to utilize a single image rather than the conventional dual image. Its discovery resulted in the fact that if one eye is shaded somewhat darker than the other, the exact amounts of which have been discussed in detail in two patents, No's.4,131,342 and 4,705,371, three dimensional (3-D) viewing is possible. In these two patents, respective inventors Leslie P. Dudley and Terry D. Beard discuss various aspects concerning the illusion of depth that is conferred on the individual viewing the phenomenon. The present investigators have confirmed that only one eye needs shading, and have discovered that the shading, as manifested in a lens, need only be gray and gradations there of.

Outdoor scenes facilitate the 3-D effect because there is considerable background. Nevertheless, in order to achieve good 3-D, it is also necessary to have very close (to the camera) foreground. This combination with the subject in between makes ideal 3-D, whether a dual image or the Pulfrich illusion is to be used.

During the nearly 70 years that have passed since the Pulfrich illusion was discovered, little commercial use has been made of it, other than Dudley's attempt at animation, until Beard and others tried to capture the illusion live, specifically, during the 1989 Pasadena Rose Parade and then the Super Bowl halftime show of the same year.

The Pulfrich illusion requires constant motion in order for the in-depth perception to be achieved. Unfortunately, when viewed with angular camera motion that is not constant in angular

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velocity or radius, or with both eyes shaded with different neutral-density value filters, many people develop various types of eye strain. These may include double vision or blurred vision, resulting in vertigo or headaches. The present invention enables people engaged in the shooting of stereoscopic illusions using the Pulfrich effect to overcome the problems inherent in capturing the illusion and, at the same time, to reduce the problems associated with viewing it. The shortcoming of the previous applications when used for this purpose will be addressed, and the means of overcoming such shortcomings disclosed.

Disclosure of Invention

In the past, 3-D pictures using the Pulfrich illusion have been shot with the foreground as close as possible to the camera and the background going back a substantial distance, or to the horizon. This becomes a critical problem (which has hindered the development of 3-D technology) when used in confined areas, because stereoscopic visualization has considerable limitations in confined spaces.

This limitation with respect to the Pulfrich illusion explains why the illusion was first used commercially to shoot the Rose Parade, the Super Bowl halftime, and outdoor commercials, all with very large foreground-to-background distances involved.

If one could apply the Pulfrich method to an area as confined as a wrestling or boxing ring, the possibilities for other uses would be enormous. Yet, having a camera directly operated by a cameraman while the camera moves continuously around the inside of, or is stationed within, a stationary ring presents impossible logistics. Minimally, the seats of the spectators would preclude having a dolly traveling in front of them and obscuring their vision.

In the present invention, the camera can be suspended from the ceiling and all operations of the camera operated remotely. The camera moves in and out, up and down, while circularly traveling around the ring. When the camera moves to its lowest position, minimal blocking of spectator viewing occurs. This is an improvement over the prior art.

The cameraman operates the camera remotely by looking at a monitor, and, with one eye shaded, the cameraman sees 3-D illusion as it is being shot. This is important to facilitate the best creative development of the event being photographed using the Pulfrich effect.

Additionally, a self-propelled vehicle, moving about on circular tracks surrounding the subjects being filmed or videotaped, may be employed. It carries a camera which itself does not move in or

out, and whose focus remains fixed for certain shots. For flat footage, the camera can change location, zoom in and out, or simply remain still, all in one scene. This camera records action anywhere in the scene.

During circular motion shots, the camera always travels at uniform (constant) angular velocity.

If more depth to the 3-D is desired, the camera is speeded up. Through advanced experimentation, present applicants have discovered that, for optimum/state of the art 3-D, an angular velocity between 25 degrees per second and 65 degrees per second will create a strong dimensional 3-D image. This improvement has been determined, after a great deal of extensive testing, to be the optimum ranges of speed for the creation of a maximum 3-D effect.

For any given radius of the camera to the object(-s) being photographed, as measured in the horizontal plane of the object(-s), that is, the true radius, the linear circumferential speed of the camera has been discovered to require constant velocity to obtain optimal depth of illusion. Stated differently, the angular velocity of the camera about the object(-s) must be invariant, for constancy in the amount of 3-D illusion, whatever the true radius of the camera to the object(-s) is.

All operational techniques discovered that elicit the 3-D illusion by usage of constant angular velocity, angular motion itself, and specific circular motion with specific radii are essential discoveries of the present invention.

When it is desirable to shoot the video indoors in a confined space, with a single scene being used repeatedly (a wrestling match, boxing match, etc.), floor space will be limited and cannot be cluttered with vehicles and tracks. Furthermore, to have tracks on the floor with moving vehicles on them in a small space will present a hazard to people who are walking about when the room is not being used for cinematography. In addition, people might desire to use the space for other purposes when there is no filming or videotaping. Finally, to have a cameraman operate a camera directly in a confined space not only obstructs the view of spectators, but, also, might interfere with the action of the scene being filmed. Yet, the camera must be instantly ready when action needs to be videotaped.

Thus, when other events need the shooting space, a fixed circular monorail or dual tracks similar to a side-by-side pair of circular curtain tracks can be attached to the ceiling with the lights placed in between and, in the case of an arena, drawn up when not in use.

Once the essential but cumbersome technique of obtaining circular camera motion to elicit 3-D illusion is accomplished, as discussed above, the next step in optimizing this 3-D illusion in a confined space is the lighting and color arrangement. Considerable lighting is required to elicit the 3-D illusion.

Fortunately, the ceiling-held rails or circular-moving arm are permanently fixed, so the lights can be attached to the ceiling out of the way of the camera and left there. Illumination approaching the intensity of daylight is required, and in a confined space this is much less of a problem than on a sound stage or in an auditorium.

For optimal 3-D illusion, the lights illuminating the filming or recording will vary in intensity and in the timing of use. Light levels iUuminating the scene nearest the camera are, typically, between 200 and 400 foot-candles intensity. Light levels illuminating the middle ground should be, typically, between 401 and 600 foot-candles intensity. Finally, light levels illuminating the background should be, typically, between 601 and 800 foot-candles intensity. Also, the timing of the lights optimizes the 3-D illusion. A number of the lights farthest from the moving camera will be, typically, sequentially shut off, while a number of those closest to the camera which have not been in use will be, typically, sequentially turned on; the sequencing of all lights being dependent on the position of the moving camera and other factors. This operational technique of dynamically altering illumination to enhance 3-D illusion originates with the present invention.

Finally, the fixed position of the lights relative to the objects being filmed is consequential. Backlighting objects, whether in the foreground, the middle ground or the background optimizes the 3-D illusion. The present investigators have built upon certain basic depth/color perception discoveries, including those placed in the public domain in 1958 by Dr. Edwin Land, inventor of the Polaroid process. The use of backlighting to optimize simulated 3-D effect is a discovery of the present invention.

Selection and placement of color is essential to elicit the 3-D illusion in a confined space. Very bright lighting, combined with an easily perceived distinction among the colors used and with a variety of colors, is necessary. Because filming is in a confined area, for optimal 3-D, the colors must range over the entire visible spectrum, although not every color is needed. Each of the layers of colors closest to the camera is typically separated by a full color in the spectrum. This discovered sequence of colors takes advantage of the natural chromostereoscopic effects of color created in the human brain. However, since the chromostereoscopic effect of the general 3-D illusion due to color is less than that created by the camera motion, the sequence of colors for color separation should be as diverse from each other as possible. In other words, each layer of color should be a primary color or a secondary color.

The contrast in colors can be enhanced by the use of colored lights interspersed with white lights to illuminate the film stage. The ratio of the chosen colored lamps to white lamps, each of the same wattage, is typically between 2:1 and 4:1, with specific ratios dependent on the color of the

colored Ughts, the colors of the scene, and the location of the colored light vis-a-vis the camera. It is recognized that the ratio of colored to white light is important, as too much colored light will reduce the foot-candles of illumination, thereby diminishing the 3-D illusion.

Novelties of the present invention include the recognition of proper selection and placement of color and color intensity, and the development of specific ratios of colored to white lighting at specific distances to the camera.

Another aspect of the present invention is to provide improved viewing three-dimensional glasses for films and videos which improve the illusion of the Pulfrich effect while avoiding adverse results; as in prior art glasses used for viewing the Pulfrich effect. These 3-D glasses, as presented in the present application, dramatically enhance the Pulfrich effect without adverse side effects. The 3-D glasses of the present invention may be used with or without the use of an electrical trolley moving in a semi- or circular motion. The 3-D viewing glasses of the present invention filter light by refection, not involving the color spectrum. This improves the 3-D effect by allowing full use of chromostereography and eases eye strain by eliminating one stage of mental processing. The brain automatically tries to match the scenes observed through each eye to one another and may do so more easily when dealing only with a difference in light intensity, without a color difference in each lens. The glasses of the present invention have one lens made of a plastic film which is coated, (as with vapor deposited metal), producing a silvery mirror effect. Since the transmissivity reduction is achieved by reflection rather than absorption, the color distortion which a viewer is normally subjected to with dyed lenses is eliminated. Hence, there are no discernible peaks in wavelength, color or spectrum which provides a specific neutral density in the range of 0.5 to 2.0. The other lens provides approximately 100% light transmission. This precise formulation of the above-mentioned 3-D glasses enhances the Pulfrich effect to the optimum degree whether it be viewed on video, film or computerized video games, with or without the use of video games, and with or without the use of an electronically controlled vehicle, moving about in a circle or semi-circle.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Brief Description of Drawings

Figure 1 illustrates a room viewed from the ceiling, with the room to have a videocamera rotate in a complete circle.

Figure 2 illustrates in detail a videocamera adapted for movement along circular tracks as in

Figure 1.

Figure 3 illustrates a section through a room in which the camera and the film stage are in the same vertical plane.

Figure 4 illustrates a pair of 3-D viewing glasses with one lens mirrored to reflect a portion of the light hitting it, with less than 50% of the intensity passed by the other lens and with no discernible wavelength, color or spectral peaks in either lens.

Modes for Carrying Out the Invention

Figure 1 illustrates camera A secured to and suspended from aluminum camera support B, comprising columnar braces attached to a motorized trolley. Variable-speed motor C moves support B and camera A upon circular tracks D. The entire assembly of camera A, support B, motor C and tracks D is suspended from the ceiling from the ceiling from guy wires E.

Figure 2 illustrates in detail the motorized trolley of Figure 1. Variable-speed motor A is remotely controlled, and moves the trolley through connection to ribbed drive belt E. Belt E is connected to ribbed belt groove casing D, which is bolted to V-groove drive wheel C. Wheel C sits upon the trolley track. As the trolley moves upon the track, restraint wheels G control the sway and, thereby, the focus of camera A, which, although not shown, is suspended by aluminum camera support B. Platform and hook F comprise means by which to slide camera A up and down along support B. Turn screw H enables tilting of the trolley and, hence, camera A.

Figure 3 illustrates the assembly of Figure 1 in relation to the film stage. Tracks D are suspended directly above the film stage, with the tracks and the film stage forming concentric circles. Subject B, prop C, and backdrop E are shown in relation to camera A.

Figure 4 illustrates a pair of viewing glasses with one lens I mirrored to reflect a portion of the light and only pass a portion of the light therethrough. The other lens J is substantially transparent. This creates a 3-D illusion as the brain processes the image coming from each eye, when these viewing glasses are used in conjunction with the constant angular motion of a camera at constant speed. Lens 1 passes light at an intensity less than 50% of the intensity passed by the other lens J. There is no discernible wavelength, color or spectral peaks in either lens. Lens J preferably provides a substantially 100% unobstructed light transmission. Lens I has a specific neutral density of 0.5-2.0.

Lens I may be a partially mirrored film formed of a plastic film with vapor deposited metal, producing a silvery mirror effect which, since the transmissivity reduction is achieved by reflection rather than absorption, eliminates the color distortion which a viewer is normally subjected to with

dyed lenses. The partially mirrored film, is preferably between 0.75 and 30 mils thick. The mirrored film exhibits two distinct modes of optical transmission, one, when measured spectroscopically, and the second, when viewed through the lenses of glasses by the human eye. The former mode is such that, when graphed upon an abscissa covering the human visual range, the curve is flat, exhibiting no discernible wavelength, color or spectral peaks, and when used as a lens, the effective neutral density is in the range of 0.5-2.0.

It is noted that the film which comprises the lens I may be formed of polyester, polycarbonate, Lexon™, or other suitable materials which provide the desired reflection and transmission characteristics.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For example, although the 3-D glasses described hereinabove are the ones that may be optimally used with the method of the present invention, it is understood that other less desirable 3-D glasses may be utilized.