<XML><RECORDS><RECORD><REFERENCE_TYPE>3</REFERENCE_TYPE><REFNUM>5931</REFNUM><AUTHORS><AUTHOR>Patterson,J.W.</AUTHOR></AUTHORS><YEAR>1993</YEAR><TITLE>Fast Spheres</TITLE><PLACE_PUBLISHED>Computer Graphics FORUM (proc. Eurographics '93) </PLACE_PUBLISHED><PUBLISHER>Oxford University Press</PUBLISHER><LABEL>Patterson:1993:5931</LABEL><KEYWORDS><KEYWORD>differences sphere-like fast integers image synthesis</KEYWORD></KEYWORDS<ABSTRACT>A new method for generating sphere-like images, using parabolic surfaces delimited by Bresenham's circle generation algorithm, is presented. In many cases the resultant images are indistinguishable from spheres illuminated from a given single direction. The main form of the algorithm uses first and second integer differences to minimise computation and uses typically not more than one floating-point calculation per sphere. Two variants of the algorithm are given, one optimized for the special case of the light-source being behind the view-point, and one in which values are calculated for a z-buffer hidden-surface algorithm at the same time as the pixel values. The difference formulae can be exploited by differencing hardware or digital signal processors although very little arithmetic, typically five low-weight integer operations, including address calculation operations, is required per pixel on a conventional architecture. </ABSTRACT><URL>http://www.eg.org/EG/CGF/Volume12/issue3/v12i3pp61-72_abstract.html</URL></RECORD></RECORDS></XML>