Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
1999-04-16
2003-09-23
Padmanabhan, Mano (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S587000, C345S619000
Reexamination Certificate
active
06624820
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a graphic processing apparatus which can provide a high quality image and a method thereof.
2. Description of the Related Art
Computer graphics are often used in a variety of computer aided design (CAD) systems and amusement machines. Especially, along with the recent advances in image processing techniques, systems using three-dimensional computer graphics are becoming rapidly widespread.
In three-dimensional computer graphics, the color value of each pixel is calculated at the time of deciding the color of each corresponding pixel. Then, rendering is performed for writing the calculated value to an address of a display buffer (frame buffer) corresponding to the pixel.
One of the rendering methods is polygon rendering. In this method, a three-dimensional model is expressed as an composite of triangular unit graphics (polygons). By drawing the polygons as units, the colors of the pixels of the display screen are decided.
In polygon rendering, coordinates (x, y, z), color data (R, G, B), homogeneous coordinates (s, t) of texture data indicating a composite image pattern and values of a homogeneous term g for the inside of a triangle are found by interpolation from the vertexes of a triangle in a physical coordinate system.
Here, the homogeneous term q is, simply stated, like an expansion or reduction rate. Coordinates in a UV coordinate system of an actual texture buffer, namely, texture coordinate data (u, v), are in accordance with the homogeneous coordinates (s, t) divided by the homogeneous term q to give (s/q, t/q)=(u, v) which in turn are multiplied by texture sizes USIZE and VSIZE, respectively.
In a three-dimensional computer graphic system using such polygon rendering, the texture data is read from the texture buffer when drawing, and texture mapping is performed for applying the read texture data on the surface of the three-dimensional model to obtain image data of a high degree of reality.
Note that when texture mapping is performed on a three-dimensional model, the expansion/reduction rate of the image indicated by the texture data to be applied to each pixel changes.
To perform the texture mapping, as a method for obtaining a high quality picture, there is the MIP MAP (texture for a plurality of resolutions) filtering method.
In the MIPMAP filtering, as shown in
FIG. 9
, a plurality of already filtered texture data
200
,
201
,
202
, and
203
corresponding to a plurality of different reducing rates are prepared in advance. By selecting texture data
205
corresponding to a reducing rate
204
of the respective pixels, the most suitable texture data
206
for the reducing rate
204
is used and the aliasing effect caused by loss of data accompanying the reduction of an image is suppressed.
Below, a texture mapping apparatus in a case of MIPMAP filtering will be explained.
FIG. 10
is a view for explaining a texture mapping apparatus
210
and
FIG. 11
is a flow chart of the processing in the texture mapping apparatus
210
.
Step S
1
: First, the texture mapping apparatus
210
receives as input data (s
1
, t
1
, q
1
), (s
2
, t
2
, q
2
), and (s
3
, t
3
, q
3
) indicating homogeneous coordinates and homogeneous terms of the vertexes of a triangle.
Step S
2
: Next, the texture mapping apparatus.
210
performs linear interpolation on the data (s
1
, t
1
, q
1
), (s
2
, t
2
, q
2
), and (S
3
, t
3
, q
3
) to obtain the data (s, t, q) indicating homogeneous coordinates and homogeneous terms of the pixels inside the triangle.
Step S
3
: In the texture mapping apparatus
210
, a built-in reducing rate calculation apparatus
212
calculates reducing rates “lod” of the pixels from the (s, t, q) data of the pixels inside the triangle.
Step S
4
: The texture mapping apparatus
210
calculates the texture coordinate data (u, v) by calculating u data obtained by dividing the s data by the q data and the v data obtained by dividing the t data by the q data for the (s, t, q) data of the pixels.
Next, the texture mapping apparatus
210
calculates the texture address (U, V) as a physical address in the texture buffer
211
from the reducing rate “lod” obtained in the reducing rate calculation apparatus and the texture coordinate data (u, v).
Step S
5
: The texture mapping apparatus
210
outputs the texture address (U, V) to the texture buffer
211
and reads the texture data (R, G, B).
Step S
6
: The texture mapping apparatus
210
performs predetermined processing on the texture data read at Step S
5
to obtain the pixel data S
210
and writes the pixel data S
210
in the display buffer
213
.
As a result, the texture data corresponding to the reducing rate “lod” among a plurality of texture data corresponding to a plurality of different reducing rates stored in the texture buffer
211
can be accessed.
To realize drawing at a high speed, there is a high speed texture mapping apparatus which performs texture mapping on a plurality of pixels in parallel and writes the pixel data in the display buffer simultaneously.
In this high speed texture mapping apparatus, as shown in
FIG. 12
, the data (s
1
, t
1
, q
1
), (S
2
, t
2
, q
2
), and (s
3
, t
3
, q
3
)of the vertexes of the triangle are processed in parallel in n number of texture mapping apparatuses
210
1
to
210
n
. The results of the processing, that is, the pixel data S
210
1
to S
210
n
, are written in the display buffer simultaneously.
Namely, texture mapping is performed in parallel (simultaneously) on a plurality of pixels.
Note that the texture mapping is performed for a triangle as a unit graphic and that processing conditions such as the reducing rate of the texture data are determined for triangles as units. Among the plurality of pixels simultaneously processed, only the results of the processing for the pixels positioned inside the triangle are valid, while the results of the processing on the pixels outside the triangle are invalid.
Summarizing the problems to be solved by the invention, the calculation to obtain the reducing rate “lod” includes many multiplication operations and division operations, so an enormous amount of calculation is required.
Therefore, as shown in
FIG. 12
, if the reducing rate calculation apparatuses
212
1
to
212
n
are built in the respective n number of texture mapping apparatuses
210
1
to
210
n
, though it is possible to realize high speed processing, there is a disadvantage that the apparatus becomes large in size.
In order to overcome the disadvantage, a method may be considered of building the reducing rate calculation apparatus in only one texture mapping apparatus among a plurality of texture mapping apparatuses performing the parallel processing, making a pixel processed by the texture mapping apparatus a representative point in obtaining the reducing rate, and using the reducing rate obtained in the reducing rate calculation apparatus in all of the texture mapping apparatuses.
In this case, the position of the pixel serving as the representative point among the plurality of pixels simultaneously processed becomes fixed.
Accordingly, there is a possibility that a pixel positioned outside of the unit graphic, that is, triangle, will becomes the representative point among the plurality of pixels simultaneously processed.
Since the reducing rates largely differ between inside and the outside of the triangle, if a pixel outside the triangle processed becomes the representative point, the most suitable texture data cannot be selected for the pixels inside the triangle. As a result, there is a disadvantage that the picture quality will be considerably degraded.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a graphic processing apparatus which can stably provide a high quality picture with a small hardware configuration and a method thereof.
According to a first aspect of the present invention, there is provided a graphic processing apparatus for expressing a three-dimensional model by a composite of a plurality of unit graphics to which common proc
Fulwider Patton Lee & Utecht LLP
Padmanabhan Mano
Sony Corporation
LandOfFree
Graphic processing method for determining representative... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Graphic processing method for determining representative..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Graphic processing method for determining representative... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3065873