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Start date: 1980 × End date: 1989 × Subject: filtering ×

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    PROOF: An Architecture for Rendering In Object Space
    (The Eurographics Association, 1988) Schneider, Bengt-Olaf; Claussen, Ute; A. A. M.Kuijk
    This paper gives a short introduction into the field of computer image generation in hardware. It discusses the two main approaches, namely partitioning in Image space and In object space. Based on the object space partitioning approach we have defined the PROOF architecture. PROOF is a system that aims at high performance and high quality rendering of raster images. high performance means that up to 30 pictures are generated in one second. The pictures are shaded and anti-allased, giving the images a high degree of realism. The architecture comprises tnree stages which are responsible for hidden surface removal, shading, and filtering respectively. The first of these stages a pipeline of object processors. Each of these processors stores and scan converts one obiect Furthermore, It interpolates the depth and the normal vector across the Object. Each object processor IS able to handle objects of a certain primitive type. The specialization of an object processor to a certain primitive type is encapsulated in a Single block called primitive processor. The Outout of the object processor pipeline is the input to a stage for shading. The illumination model employed takes In~o account both diffuse and specular reflections. The paper reviews Gouraud and Phong shading with regard to their suitability for a hardware implementation. The final stage of the PROOF system is formed by a stage for filtering the colours of those objects that contribute to a pixel. This done by constructing a subpixel mask and filtering across an area of 2x2 pixels. At the end. the paper briefly reports on the current state of the project.
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    VLSI Architecture for Anti-Aliasing
    (The Eurographics Association, 1989) Romanova, Claudia; Wagner, Ulrich; Richard Grimsdale and Wolfgang Strasser
    Computer-synthesized images exhibit the typical artifacts of raster displays, called alias­ ing, rastering, staircasing or the "jaggies". Display of an image on a raster CRT requires the sampling the two dimensional image signal I( x, y) to obtain a pixel-based description of intensity. Unfortinately, this sampling process treates the pixel as a mathematical point and the point sampling of an unfiltered object is never correct at any resolution. Aliasing effects (spatial and temporal) are due to undersampling of the image signal. Spatial aliasing occurs when images contain frequencies greater than one half the spa­ tial sampling frequency. Lines that should be straight appear jagged, very small objects may not be visible, portions of long thin objects may disappear.