Other early developments of the scanline rendering method were by Bouknight in 1969, and Newell, Newell, and Sancha in 1972. The first publication of the scanline rendering technique was probably by Wylie, Romney, Evans, and Erdahl in 1967. In another variant, an ID buffer is rasterized in an intermediate step, allowing deferred shading of the resulting visible pixels. Variants Ī hybrid between this and Z-buffering does away with the active edge table sorting, and instead rasterizes one scanline at a time into a Z-buffer, maintaining active polygon spans from one scanline to the next. After updating edges, the active edge table is traversed in X order to emit only the visible spans, maintaining a Z-sorted active Span table, inserting and deleting the surfaces when edges are crossed. Active edge table entries are maintained in an X-sorted list, effecting a change when 2 edges cross. The active edge table entries have X and other parameter information incremented. To rasterize the next scanline, the edges no longer relevant are removed new edges from the current scanlines' Y-bucket are added, inserted sorted by X coordinate. Entries maintain sort links, X coordinates, gradients, and references to the polygons they bound. The usual method starts with edges of projected polygons inserted into buckets, one per scanline the rasterizer maintains an active edge table ( AET). This kind of algorithm can be easily integrated with many other graphics techniques, such as the Phong reflection model or the Z-buffer algorithm. The main memory is often very slow compared to the link between the central processing unit and cache memory, and thus avoiding re-accessing vertices in main memory can provide a substantial speedup. Another advantage is that it is not necessary to translate the coordinates of all vertices from the main memory into the working memory-only vertices defining edges that intersect the current scan line need to be in active memory, and each vertex is read in only once. The main advantage of this method is that sorting vertices along the normal of the scanning plane reduces the number of comparisons between edges. All of the polygons to be rendered are first sorted by the top y coordinate at which they first appear, then each row or scan line of the image is computed using the intersection of a scanline with the polygons on the front of the sorted list, while the sorted list is updated to discard no-longer-visible polygons as the active scan line is advanced down the picture. Scanline rendering (also scan line rendering and scan-line rendering) is an algorithm for visible surface determination, in 3D computer graphics, that works on a row-by-row basis rather than a polygon-by-polygon or pixel-by-pixel basis. It's slightly more impressive than AT&T's film - and almost as fun.3D computer graphics image rendering method Scan-line algorithm example Raster graphics were used to show Robo-Brenner's POV. But what do you expect? It was 1964.Īnother decade would pass before computer animation made it into an honest-to-goodness feature film: 1973's Westworld, where a robotic Yul Brenner battles Richard Benjamin inside the amusement park of the future. Yes, the animation is on the simple side - tiny boxes and circles rolling down ramps. "This film describes a method by which much the tedious work of animation can be done by an electronic computer." Little did they know that computer animation would change so much more.Īt Bell Labs, Knowlton created a programming language known as BEFLIX - four decades before the arrival of Netflix - and when paired with an IBM 7094 mainframe and a Stromberg-Carlson microfilm printer, the language could produce raster-scan images - aka bitmaps - that could them be printed onto good-old-fashioned film stock: "Animated movies are usually made by a slow and complex process involving the coordinated efforts of many artists," it says. The researchers bill this technique as a means of simplifying animation - and, yes, reducing the number of people needed for the task.
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