Method and apparatus for rendering a two dimensional image from three dimensional image data
First Claim
1. An image processing method for rendering a two dimensional output image comprised of pixels from three dimensional image data, wherein a random polyhedron is projected from a location of viewing as a two dimensional polygon having a boundary enclosing an area and defined in three dimensional space and pixel images from a two dimensional input image are mapped onto pixels within said projected two dimensional polygon, comprising the steps of:
- providing a plurality of look-up tables each with a set of perspective correction factors corresponding to a location of viewing;
identifying at least two boundary points on said boundary of said polygon;
mapping pixels within said two dimensional input image corresponding to each of said at least two points on said polygon boundary according to a defined mapping function;
identifying a locus of pixels within said polygon extending between said at least two boundary points; and
mapping pixels within said two dimensional input image to each of said pixels of said locus of pixels within said polygon by (i) linearly interpolating at least one coordinate of each pixel along said locus of pixels to obtain an interpolated coordinate, (ii) identifying the look-up table corresponding to the location of viewing from which said two dimensional polygon was projected;
(iii) applying a correction factor from the set of correction factors in the selected lookup table to the interpolated coordinate to obtain a corrected coordinate for the pixel to be mapped from the two dimensional input image.
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Abstract
Texture mapping or video mapping is performed in such a way as to obtain perspectively correct images, while at the same time not requiring excessive computational overheads. Non-linear functions required to achieve perspectively correct images are stored in the form of look-up tables. Depth extents at the extremes of a locus of interpolation are compared and from this comparison a particular look-up table, or a pair of look-up tables, are selected. When a pair of look-up tables are selected, it is possible to linearly interpolate between the two, in order to obtain a closer approximation to the desired non-linear response.
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Citations
26 Claims
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1. An image processing method for rendering a two dimensional output image comprised of pixels from three dimensional image data, wherein a random polyhedron is projected from a location of viewing as a two dimensional polygon having a boundary enclosing an area and defined in three dimensional space and pixel images from a two dimensional input image are mapped onto pixels within said projected two dimensional polygon, comprising the steps of:
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providing a plurality of look-up tables each with a set of perspective correction factors corresponding to a location of viewing;
identifying at least two boundary points on said boundary of said polygon;
mapping pixels within said two dimensional input image corresponding to each of said at least two points on said polygon boundary according to a defined mapping function;
identifying a locus of pixels within said polygon extending between said at least two boundary points; and
mapping pixels within said two dimensional input image to each of said pixels of said locus of pixels within said polygon by (i) linearly interpolating at least one coordinate of each pixel along said locus of pixels to obtain an interpolated coordinate, (ii) identifying the look-up table corresponding to the location of viewing from which said two dimensional polygon was projected;
(iii) applying a correction factor from the set of correction factors in the selected lookup table to the interpolated coordinate to obtain a corrected coordinate for the pixel to be mapped from the two dimensional input image.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. Image processing apparatus arranged to render a two dimensional output image comprised of pixels from three dimensional image data, wherein a random polyhedron is projected from a location of viewing as a two dimensional polygon having a boundary enclosing an area and defined in three dimensional space and pixel values from a two dimensional input image are mapped onto pixels within the projected polygon, comprising:
processing means including means for identifying at least two boundary points on said boundary of said polygon, for mapping pixels within said two dimensional input image corresponding to each of said at least two points on said polygon boundary according to a defined mapping function, for identifying a locus of pixels within said polygon extending between said at least two boundary points, and for mapping pixels within said two dimensional input image to each of said pixels of said locus of pixels within said polygon by (i) linearly interpolating at least one coordinate of each pixel along said locus of pixels to obtain an interpolated coordinate, (ii) identifying the look-up table corresponding to the location of viewing from which said two dimensional polygon was projected;
(iii) applying a correction factor from the set of correction factors in the selected lookup table to the interpolated coordinate to obtain a corrected coordinate for the pixel to be mapped from the two dimensional input image.- View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
Specification