Computer graphics processing and selective visual display system – Computer graphics processing – Graph generating
Reexamination Certificate
1997-03-25
2001-09-04
Brier, Jeffery (Department: 2672)
Computer graphics processing and selective visual display system
Computer graphics processing
Graph generating
C345S426000
Reexamination Certificate
active
06285373
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application related to computer graphics generation, and specifically to the storage and generation of three-dimensional computer graphics texture data.
Texture mapping is an important part of 3D graphics. In its simplest form texture mapping involves the mapping of a digital texture image onto a 3 dimensional surface. The texture adds detail and realism to the surface appearance. A typical graphics system reads data from a texture map, processes it, and writes color data to display memory. The processing may include mipmap filtering which requires access to several maps. The texture map need not be limited to colors, but can hold other information that can be applied to a surface to affect its appearance; this could include height perturbation to give the effect of roughness. The individual elements of a texture map are called “texels.”
Since the surfaces are transformed (by the host or geometry engine) to produce a 2D view, the textures will need to be similarly transformed by a linear transform (normally projective or “affine”). (In conventional terminology, the coordinates of the object surface, i.e. the primitive being rendered, are referred to as an (s,t) coordinate space, and the map of the stored texture is referred to a (u,v) coordinate space.) The transformation in the resulting mapping means that a horizontal line in the (x,y) display space is very likely to correspond to a slanted line in the (u,v) space of the texture map, and hence many page breaks will occur, due to the texturing operation, as rendering walks along a horizontal line of pixels.
Texture patterns are commonly used as a way to apply realistic visual detail at the sub-polygon level. See Foley et al., COMPUTER GRAPHICS: PRINCIPLES AND PRACTICE (2.ed. 1990, corr. 1995), especially at pages 741-744; Paul S. Heckbert, “Fundamentals of Texture Mapping and Image Warping,” Thesis submitted to Dept. of EE and Computer Science, University of California, Berkeley, Jun. 17, 1994; Heckbert, “Survey of Computer Graphics,” IEEE Computer Graphics, November 1986, pp.56ff; all of which are hereby incorporated by reference.
A recurrent problem with texture mapping is the amount of data each texture map contains. If it is of high quality and detail it may require a substantial amount of storage space. The size of texture maps may be greatly increased if mipmap filtering is supported.
Mip Mapping is a technique to allow the efficient filtering of texture maps when the projected area of the fragment covers more than one texel (i.e. minification). A hierarchy of texture maps is held with each one being half the size (or one quarter the area) of the preceding one. A pair of maps are selected, based on the projected area of the texture. In terms of filtering this means that three filter operations are performed: one on the first map, one on the second map and one between the maps. The first filter name (Nearest or Linear) in the mipmap name specifies the filtering to do on the two maps, and the second filter name specifies the filtering to do between maps.
The filtering process takes a number of texels and interpolants, and with the current texture filter mode produces a texture color.
Moving textures from one place to another may be a time consuming operation. In a normal graphics system the time taken to transfer a texture from disk or system memory to the graphics system may be significantly more than the time taken to apply the texture. Network applications, in which the application and graphics system are on separate machines linked by a low bandwidth connection amplify this problem. Improvements can be made by caching the texture locally in the graphics system, but the time taken to transfer it just once may be prohibitive.
BACKGROUND
Graphics in Telecommunications
As interactive telecommunications become more pervasive, it becomes increasingly important to limit required bandwidth as much as possible while providing a high-quality appearance.
The use of three-dimensional graphics is becoming common in many applications, ranging from business applications, to gaming software, to 3D “web page” graphics. More detailed graphics necessarily require a greater amount of data to produce, and interactive 3D graphics require a very large amount of data per displayed pixel. For telecommunications applications, the amount of data that can be displayed in a reasonable amount of time is limited, so it is commonly unworkable to transmit 3D texture data.
BACKGROUND
Typographic Font Libraries
It has become common in current computer systems to store on each system a library of typographic font descriptions for commonly used typefaces. By doing so, it is unnecessary for each software application to provide a full description of each font it uses; it simply makes reference to the common font library, indicating the required font set and character number. The same font library is also used for common non-typographic character sets, e.g. the common “dingbats” font. By using these font libraries, it is possible to cut down on the bandwidth required for transmitting text to be displayed in a particular font.
Innovative Texture Generation and Storage System
The present application discloses a texture library system and method which removes the need to transfer the complete texture from the application to the drawing engine. Instead, the application sends a reference which the graphics system understands and uses to select a local texture map. The exact texture used by the drawing engine is not known to the application, but industry agreement ensures that a particular reference will produce adequately similar results on compliant systems.
The texture library is a mechanism for reducing the amount of information that needs to be transferred between an application and a graphics system when displaying three dimensional graphics. It gives benefits to suppliers of applications because performance can be greatly improved. It also gives benefits to suppliers of graphics systems because it conceals the format of textures; in this way, graphics systems will only be required to accept textures in library format, with normalized dimensions, and will not be required to design systems to accommodate varying texture formats.
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Heckbert, Paul S., “Fundamentals of Texture Maping and Image Warping”, Thesis submitted to Dept of EE and Computer Science, Univ of California, Berkeley, Jun. 17, 1989, p. 1-86.
Foley et al., “Computer Graphics:Principles and Practice” 2 ed. 1990, corr. 1995 especially at pp. 741-744.
Heckbert,Paul “Survey of Texture Mapping”, IEEE Computer Graphics, Nov. 1986, pp. 56-66.
Baldwin David Robert
Bigos Andrew
Kent Osman
Murphy Nicholas J. N.
3DLabs Inc. Ltd.
Brier Jeffery
Formby Betty
Good-Johnson Motilewa
Groover Robert
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