Scan Conversion Of Straight Lines And Straight-line Anti-aliasing

The line as the basic primitive on raster graphics drawing plays an important role, manycomplex graphics are formed by the line. The speed and quality of drawing line effect thegraphics drawing on a great deciding factor.This paper describes the current linear scan conversion algorithm, including the DDAalgorithm, Bresenham algorithm, and multi-point linear scan conversion algorithm include thetwo-way symmetrical algorithm, N-step algorithm, these algorithms can facilitate get thepixels of the line, but the straight line boundary has sawtooth and aliasing. And then, Thispaper describes the commonly anti-aliasing methods, including distance-weightedanti-aliasing, area-weighted anti-aliasing and weighted regional filter anti-aliasing, by thesemethods can effectively reduce the aliasing phenomenon.Then, The paper presents several improved algorithms based on the algorithms thatdescribed. The paper presents multi-segment linear scan conversion algorithm and theanti-aliasing algorithm based on the linear multi-segment similarity and the analysis of thelinear relationship between the relative positions of discrete pixels, these algorithm is moreefficiency than Bresenham algorithm in the common denominator is greater than 3. Thepaper also presents 4-step line generating algorithm based on symmetry, which is based thetheory of N-step line generating algorithm and the two-way symmetrical algorithm. Thisalgorithm draws 8 pixels on the one loop, improves the speed of the line-generating. Thispaper improves the area-weighted anti-aliasing algorithm. The new algorithm simplify theoperation of covered area of pixels, by add a discriminant, made algorithm implementationmore simple and efficient.Finally, this paper studies the multi-pixel wide linear anti-aliasing according to therequirements of the compass display in Aircraft Cockpit. And points out the errors of theliterature, presents the correct multi-pixel wide linear anti-aliasing algorithm based ondistance-weighted anti-aliasing; In order to realizing in the hardware easily and improvingoperational efficiency, the paper also studies the integralization method based on the distance-weighted anti-aliasing algorithm.