Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1998-11-18
2002-01-29
Zimmerman, Mark (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
C345S419000
Reexamination Certificate
active
06342887
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to computer animation and visual effects. In particular, this invention relates to a method and apparatus for reproducing real-world lighting effects in a three dimensional computer animated object.
BACKGROUND OF THE INVENTION
Visual effects used in movies and television programs have become extremely sophisticated in recent years. Older, more cumbersome methods of creating three dimensional physical models of fictitious creatures and objects and animating them on a scaled-down physical set through frame-by-frame motion manipulation have largely been replaced by the widespread availability of software for creating “three dimensional” computer models of animated objects, so-called because they exhibit surface qualities and lighting effects which simulate those of a three dimensional object. It is now commonplace to create a three dimensional computer model of an object and integrate the animated object as a visual effect into a cinematographic scene, which is a more realistic and more versatile method of creating visual effects creatures and objects.
Three dimensional computer-generated images of animated characters and objects can be modeled to be extremely realistic in appearance. The most popular computer programs presently available for creating three dimensional computer animated objects allow the animator to create a model of an object in three dimensions, specify the position of one or more synthetic light sources, and then apply basic rules of theoretical optics to generate lighting effects which mimic realistic three dimensional reflection patterns along the contours of the various surfaces of the model. This method has proven satisfactory for creating animated objects within an animated setting, because all of the images in the frame are subjected to the same synthetic light sources and all lighting effects are processed according to the same rules.
However, such a commercially available computer modeling programs cannot create a realistic visual effect object for integration into a real-world cinematographic scene. This is a much more difficult problem, because the computer animated object must blend seamlessly, and be consistent in all respects, with the images of the physical objects with which the visual effect will coexist in the cinematographic scene. Otherwise the visual effect will not be realistic and will lose its entertainment value to today's sophisticated viewers.
One of the most important factors affecting the degree of realism obtained when an animated object is integrated with a real-world cinematographic object is consistency between the real-world and animated lighting effects. In order for the computer animated object to be perceived by a viewer as properly belonging within a real-world scene, synthetic lighting effects on the animated object must be perfectly consistent with the physical lighting effects that a comparable physical object would exhibit if placed on the physical set in the same position as the animated object. Even slight deviations in shadowing, reflection angles, coloring or light intensity are perceived by the viewer as anomalies, either consciously or unconsciously, and can significantly reduce or destroy the believability of the visual effect.
Conventional methods for integrating computer animated objects into real-world cinematographic objects involve first shooting the cinematographic scene on a physical set, with stationary and moving objects as they will appear in the finished cinematographic scene. The physical set and the objects in it are carefully illuminated by various types of light sources selected, positioned, oriented and often modified (eg. by dimmers and filters) according to the lighting effects desired to be achieved in each particular scene. A three dimensional model of the visual effects object is then created on a computer and processed by conventional modeling software, and the image is superimposed onto each frame of the cinematographic scene to create the composite cinematographic picture.
The basic optical parameters used in conventional three dimensional modeling software can be used to provide a starting point for the rendering of computer animated three dimensional objects for use as visual effects objects. However, the result is invariably unsuitable when the animated object is incorporated into a real-world scene because these parameters are developed from theoretical optics principles and do not factor in many real-world optical parameters. As such, the synthetic lighting of the animated object can never match the actual lighting effects applied to objects on the physical set as manifest in the cinematographic reproduction.
Thus, after incorporating the computer animated object into the cinematographic scene the animated object must be altered to be consistent with the lighting effects used on the physical set. This is a painstaking process which generally takes days or weeks of skilled visual effects artists adapting each shot, sometimes frame by frame, to match the lighting of each computer animated object with the lighting effects that would be exhibited by a comparable physical object on the physical set.
Apart from the tremendous cost involved in such an undertaking it is virtually impossible using this method, even for the most highly skilled visual effects artist, to achieve an exact reproduction of the lighting effects on the physical set so that the incorporation of an independently created computer animated object into the real-world cinematographic object is completely realistic. There are thousands of shades and hues of each colour in the spectrum, and while the human eye is capable of discerning only a few hundred at a conscious level smaller differences are noticeable as anomalies at an unconscious level.
This process is also monitor-dependent, to the extent that different computer monitors display slightly different colours, shades and hues, producing latent anomalies that can become apparent when the animated object is displayed on a different monitor or incorporated into a composite cinematographic scene. Differences between animated and real-world colours, shades and hues which may have been indistinguishable to visual effects artists, either due to the characteristics of the computer monitor used or due to the inability of the human eye to distinguish between fine differences in colours, shades and hues, can become apparent in the composite image and can destroy the believability of the visual effect.
This problem is exacerbated by the numerous factors which can affect the lighting of a cinematographic scene, including the positioning, orientation, luminous intensity and colour of each light source, changes in luminous intensity and colour due to filters, dimmers and light occlusion by opaque objects, diffusion and attenuation due to the position of the animated object, optical transmission characteristics of the camera lens, the sensitivity of the cinematographic film used in filming the scene, film colour balance, frame rates and shutter openings. All of these factors combine to create many diverse and unique lighting effects in a cinematographic scene, and while this diversity is useful to directors of lighting and cinematography in practising their craft, the resulting lighting effects can be extremely difficult even to approximate in a computer model, let alone duplicate.
It would accordingly be advantageous to provide a method and apparatus for applying lighting effects to a three dimensional computer animated object which are consistent in all respects with the lighting effects used on a real-world cinematographic set, such that upon integrating the animated object into the cinematographic scene to form a composite cinematographic image, the animated object is indistinguishable from a comparable physical object occupying the same position and performing the same motion as the computer animated object.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for reproducing real-world (physical) lighti
Dimock Stratton Clarizio
Eisen Mark B.
Sealey Lance W.
Zimmerman Mark
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