Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1999-06-17
2002-06-04
Vo, Cliff N. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
Reexamination Certificate
active
06400365
ABSTRACT:
TECHNICAL FIELD
The present invention concerns the technology which displays the object shape created by the given shape generating system and/or equipment in virtual space, that is the computer world, in order to make a reduction of the target object into real space, that is the physical world, and the technology which realizes what is called virtual reality including the simulation technique.
Of course, the present invention is positioned as the technology which includes the field related to the video image generating technology, for example, as the technology which fulfills the roll to say that the rebuilt image can be made by information projected as the target object in the real world based on information in virtual space through shape input devices.
Namely, the present invention is the interface technology which constructs the cross link between the real world and virtual space, and not only the virtual reality generating technology for the world of the multi-media in a strict sense but also the indispensable one for the general presentation technology, especially the communication with the image in Internet, etc. Incidentally, the present invention is regarded as a basis technology of what is called VRML (Virtual Reality Modeling Language) in the field of the communication technology concerning information of the image. Therefore, a more usable, effective and efficient communication tool can be offered in mechanical communication for the multimedia environment, etc.
Moreover, the present invention provides a more freely constructive means and an efficient tool for bi-direction games, etc. in the complicated execution environment, making it possible to offer a more efficient and comfortable environment for developing and generating video game software. In addition to the field of the former technology, the present invention plays an important role in the technology effectively applicable for not only CAD and/or CAM, but also medical fields as an innovative supporting technology of a diagnostic technique by the visual image.
BACKGROUND ART
FIG. 9
shows the principle of “ray tracing”, which is one of the conventional techniques of the rendering method. By this method, the 3D image of target object shapes is displayed on a display screen.
In the ray tracing method, a curved surface body as shown in
FIG. 9
can be expressed according to a kind of analytic function, and an intersecting point on the target body can be naturally decided with a straight line (a line-of-sight or a view line) which passes through setting viewpoint E and given function which represents the surface of the target shape.
In this method, the image of the target shape is formed by a cluster of these pixels as a projecting position of the target shape corresponding with surface composing points on the target body with respect to pixels in which intersecting points exist. An intersecting point is determined between the straight line and function represented as the quadric surface when the target shape is regarded as the quadric surface. In this case, the intersecting point decision problem means the solution of the quadratic equation. It is an approximate means of algebraically solving a problem to solve the quadratic equation for determining the intersecting point, and so the target shape can be essentially limited to the quadric surface. Naturally, the higher order (over the 2nd order) curved surface of the target shape cannot be realistically dealt with because of the difficulty in solving equations over the 2nd order related to the prior art, for example, the 3rd order equation. Therefore, in regards to general shapes, the rendering technique is required for an approximate curved surface and the complicated and difficult shape process is also required.
Thus, in the prior art, there are some big problems. For example, one problem is that the extreme limit of applied shape conditions might exist when the ray tracing method is applied. Another is that the calculating efficiency and the picture quality are very low in this method.
In the conventional ray tracing method, it is necessary to decide a normal line (or merely called “normal”) at the intersecting point between a line-of-sight and display screen in order to determine the ray locus represented as a straight line, that is propagation of the light, and its luminosity. Except for the special case like a spherical surface, a normal line can be obtained by differentiating the analytic function which expresses the curved surface. In this case in which the intersecting point is obtained, the more difficult problem on a differential operation of function must be caused.
Obviously, the ray can be usually decided based on the reflection and/or the refraction of the light which is calculated with a normal line as a standard method, and a surface point of the target shape existing on the line of the ray defined as the passing locus of the ray can be determined by the same technique of examining the intersecting point in a view line. There is also the same problem when a surface point of the target shape existing in a line of ray is determined.
In the ray tracing method, fundamentally, the determining process must be continued as long as a shape composing point exists in the passing locus of ray. Therefore, in this method, the above calculating and determining process must be also repeated against all pixels on a display screen. Because of the reason related as above, the calculating efficiency become lower and lower if more reality of the target image is needed, and so the dynamic rendering process can be almost impossible.
As another rendering technique, the polygon smoothing method is well known as well as the ray tracing method. As for the ray tracing method, a target shape of virtual space is faithfully formed by tracing along the locus of ray propagation as an image because this ray tracing method accurately constructs the situation of the real world projected by light, while the polygon smoothing method is a concise method considerably simplified with respect to the passing locus which propagates light. In the polygon smoothing method, a 3D shape body can be expressed as a polyhedron, and so this method is applied for only the polygon which is the component of a polyhedron-like shape. That is to say, for example, using the polygon smoothing method, a curved surface can be constructed as a mere aggregate of the minute plane because a curved surface can be expressed as an approximate polyhedron with the closed density of the minute planes.
For the polyhedron with a closed density, it is theoretically possible to apply the ray tracing method. Naturally, it is possible that a formulated equation is established when the intersecting point between a straight line and minute plane which composes the polyhedron should be obtained.
However, a number of the above composing planes of a polyhedron is required in order to raise the higher degree of approximation of the expression as a polyhedron, and a higher density of said composing plane of polyhedron body is necessary. The calculation under the condition as related above is impractical because the amount of the calculation can be enormous when the calculation of the polygon smoothing method is applied in the polyhedron with the higher density of composing planes.
It is naturally concluded that the polygon smoothing method might be applied as the rendering method without considering the degradation of image quality to be formed in order to break through the above problems and as an alternative method for the ray tracing method to be devised in order to clear the limit of the target shape processed by the ray tracing method.
In the meantime, the polygon smoothing method is due to such a method as processing based on the plain-like shape which constructs a surface of a polyhedron and projecting shape which composes the points of the polyhedron on a display screen by means of the clairvoyance and projection method. The shape image with surface composing points of the projected polyhedron is clearly made up as a l
Koda & Androlia
Vo Cliff N.
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