Computer graphics processing and selective visual display system – Computer graphics processing – Graphic manipulation
Reexamination Certificate
2000-11-17
2003-09-16
Bella, Matthew C. (Department: 2676)
Computer graphics processing and selective visual display system
Computer graphics processing
Graphic manipulation
C345S630000, C345S632000, C345S589000, C345S594000, C345S598000, C345S606000
Reexamination Certificate
active
06621500
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to techniques for rendering graphical data and, in particular, to systems and methods for utilizing a plurality of graphics pipelines to render graphical data to a display device.
2. Related Art
Computer graphical display systems are commonly used for displaying graphical representations of two-dimensional and/or three-dimensional objects on a two-dimensional display device, such as a cathode ray tube, for example. Current computer graphical display systems provide detailed visual representations of objects and are used in a variety of applications.
FIG. 1
depicts an exemplary embodiment of a conventional computer graphical display system
15
. A graphics application
17
stored on a computer
21
defines, in data, an object to be rendered by the system
15
. To render the object, the application
17
transmits graphical data defining the object to graphics pipeline
23
, which may be implemented in hardware, software, or a combination thereof. The graphics pipeline
23
, through well known techniques, processes the graphical data received from the application
17
and stores the graphical data in a frame buffer
26
. The frame buffer
26
stores the graphical data necessary to define the image to be displayed by a display device
29
. In this regard, the frame buffer
26
includes a set of data for each pixel displayed by the display device
29
. Each set of data is correlated with the coordinate values that identify one of the pixels displayed by the display device
29
, and each set of data includes the color value of the identified pixel as well as any additional information needed to appropriately color or shade the identified pixel. Normally, the frame buffer
26
transmits the graphical data stored therein to the display device
29
via a scanning process such that each line of pixels defining the image displayed by the display device
29
is consecutively updated.
When large images are to be displayed, multiple display devices may be used to display a single image, in which each display device displays a portion of the single image. In such an embodiment, the multiple display devices are treated as a single logical screen (SLS), and different portions of an object may be rendered by different display devices.
FIG. 2
depicts an exemplary embodiment of a computer graphics system
41
capable of utilizing a plurality of display devices
31
-
34
to render a single logical screen. In this embodiment, a client computer
42
stores the application
17
that defines, in data, an image to be displayed. Each of the display devices
31
-
34
may be used to display a portion of an object such that the display devices
31
-
34
, as a group, display a single large image of the object.
To render the object, graphical data defining the object is transmitted to an SLS server
45
. The SLS server
45
routes the graphical data to each of the graphics pipelines
36
-
39
for processing and rendering. For example, assume that the object is to be positioned such that each of the display devices
31
-
34
displays a portion of the object. Each of the pipelines
36
-
39
renders the graphical data into a form that can be written into one of the frame buffers
46
-
49
. Once the data has been rendered by the pipelines
36
-
39
to the point that the graphical data is in a form suitable for storage into frame buffers
46
-
49
, each of the pipelines
36
-
39
performs a clipping process before transmitting the data to frame buffers
46
-
49
.
In the clipping process, each pipeline
36
-
39
discards the graphical data defining the portions of the object that are not to be displayed by the pipeline's associated display device
31
-
34
(i.e., the display device
31
-
34
coupled to the pipeline
36
-
39
through one of the frame buffers
46
-
49
). In other words, each graphics pipeline
36
-
39
discards the graphical data defining the portions of the object displayed by the display devices
31
-
34
that are not coupled to the pipeline
36
-
39
through one of the frame buffers
46
-
49
. For example, pipeline
36
discards the graphical data defining the portions of the object that are displayed by display devices
32
-
34
, and pipeline
37
discards the graphical data defining the portions of the object that are displayed by display devices
31
,
33
, and
34
.
Thus, each frame buffer
46
-
49
should only store the graphical data defining the portion of the object displayed by the display device
31
-
34
that is coupled to the frame buffer
46
-
49
. At least one solution for providing SLS functionality in an X Window System environment is taught by Jeffrey J. Walls, Ian A. Elliott, and John Marks in U.S. Pat. No. 6,088,005, filed Jan. 10, 1996, and entitled “Design and Method for a Large, Virtual Workspace,” which is incorporated herein by reference.
A plurality of networked computer systems are often employed in implementing SLS technology. For example, in the embodiment shown by
FIG. 2
, the client
42
, the SLS server
45
, and the individual graphics pipelines
36
-
39
may each be implemented via a single computer system interconnected with the other computer systems within the system
41
via a computer network, such a local area network (LAN), for example. The X Window System is a standard for implementing window-based user interfaces in a networked computer environment, and it may be desirable to utilize X Protocol in rendering graphical data in the system
41
. For a more detailed discussion of the X Window System and the X Protocol that defines it, see Adrian Nye,
X Protocol Reference Manual Volume Zero
(O'Riley & Associates 1990).
U.S. patent application Ser. No. 09/138,456, filed on Aug. 21, 1998, and entitled “3D Graphics in a Single Logical Screen Display Using Multiple Remote Computer Systems,” which is incorporated herein by reference, describes an SLS system of networked computer stations that may be used to render two-dimensional (2D) and three-dimensional (3D) graphical data. In the embodiments described by the foregoing patent application, X Protocol is generally utilized to render 2D graphical data, and OpenGL Protocol (OGL) is generally used to render 3D graphical data.
Although it is possible to render 2D and/or 3D data in conventional computer graphical display systems, including SLS environments, there exists limitations that restrict the performance and/or image quality exhibited by the conventional computer graphical display systems. More specifically, high quality images, particularly 3D images, are typically defined by a large amount of graphical data, and the speed at which conventional graphics pipelines
36
-
39
can process the graphical data defining an object is limited. Thus, a trade-off often exists between increasing the quality of the image rendered by a computer graphical display system and the speed at which the image can be rendered, and there exists a need in the industry for better techniques and systems for rendering graphical data.
SUMMARY OF THE INVENTION
Briefly described, the present invention relates to utilizing a plurality of graphics pipelines to render graphical data to a display monitor. In this regard, embodiments of the present invention may be construed as providing methods for producing a composite digital video data stream, which contains data corresponding to an image to be rendered. A preferred embodiment includes the step of receiving multiple digital video data streams. Preferably, a first of the multiple digital video data streams contains processed pixel data corresponding to at least a portion of the image to be rendered, and a second of the multiple digital video data streams contains processed pixel data corresponding to at least a portion of the image to be rendered as well as information, such as a chroma-key value, associated with at least some of the processed pixel data. The embodiment also includes the step of combining the multiple digital video data streams into the composite digital video data strea
Alcorn Byron A
Gee Joseph Norman
Hoffman Don B.
Lefebvre Kevin
Bella Matthew C.
Rahmjoo Mike
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