Method and apparatus for texture level of detail dithering
First Claim
1. In a computer image generation system for generating an image of an object by controlling the value of pixels forming the image of the object, the value for each pixel being derived from stored data including texture data for applying texture to the object, the texture data being stored in a sequence of texture maps consisting of a plurality of levels of detail (LODs) versions of the texture data, a method of transitioning between LODs for applying the texture to the object, the method comprising:
- computing a texture LOD value for each pixel representing the image of the object;
providing a dithering offset value for and an LOD bias value each pixel;
for each pixel, combining the dithering offset value, the LOD bias value, and the computed LOD value for the pixel to obtain a dithered pixel LOD value for each said pixel; and
outputting the dithered pixel LOD value for each pixel for selecting an associated texture LOD map.
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Accused Products
Abstract
A computationally efficient method for minimizing the visible effects of texture LOD transitions across a polygon. The minimization is accomplished by adding a dithering offset value to the LOD value computed for each pixel covered by a graphics primitive to produce a dithered pixel LOD value. The dithering offsets mat be generated from a table look-up based on the location of the pixel within a span of pixels. The dithered pixel LOD value is used to as an index in the selection of a single LOD texture map from which a textured pixel value is retrieved. The range of dithering offset values can be adjusted by modulating the values in the table look-up.
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Citations
19 Claims
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1. In a computer image generation system for generating an image of an object by controlling the value of pixels forming the image of the object, the value for each pixel being derived from stored data including texture data for applying texture to the object, the texture data being stored in a sequence of texture maps consisting of a plurality of levels of detail (LODs) versions of the texture data, a method of transitioning between LODs for applying the texture to the object, the method comprising:
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computing a texture LOD value for each pixel representing the image of the object;
providing a dithering offset value for and an LOD bias value each pixel;
for each pixel, combining the dithering offset value, the LOD bias value, and the computed LOD value for the pixel to obtain a dithered pixel LOD value for each said pixel; and
outputting the dithered pixel LOD value for each pixel for selecting an associated texture LOD map. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a computer image generation system for generating an image of an object by controlling the value of pixels forming the image of the object, the value for each pixel being derived from stored data including texture data for applying texture to the object, the texture data being stored in a sequence of texture maps consisting of a plurality of levels of detail (LOD) versions of the texture data, a method of transitioning between LODs for applying the texture to the object, an apparatus for determining the LODs to be used for each pixel that reduces artifacts when transitioning between LODs when applying texture to the object, the apparatus comprising:
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a dither pattern function generator for generating a dithering offset value for each pixel representing the image of the object to be textured; and
an input for providing an LOD bias value;
a combiner for receiving a computed pixel LOD value, a dithering offset value, and the LOD bias value for each said pixel, said dithering offset value being received from said dither pattern function generator, and for combining said computed pixel LOD value, the dithering offset value and the LOD bias value to produce a dithered pixel LOD value for each pixel. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification