Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site turtlevax.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxr!mhuxt!houxm!ihnp4!pesnta!amd!turtlevax!ken From: ken@turtlevax.UUCP (Ken Turkowski) Newsgroups: net.graphics Subject: Re: Texture mapping Message-ID: <809@turtlevax.UUCP> Date: Wed, 3-Jul-85 03:01:34 EDT Article-I.D.: turtleva.809 Posted: Wed Jul 3 03:01:34 1985 Date-Received: Thu, 4-Jul-85 04:19:48 EDT References: <221@cmu-cs-h.ARPA> Reply-To: ken@turtlevax.UUCP (Ken Turkowski) Organization: CADLINC, Inc. @ Menlo Park, CA Lines: 29 In article <221@cmu-cs-h.ARPA> rfb@cmu-cs-h.ARPA (Rick Busdiecker) writes: >Does anyone have an algorithm they'd be willing to share for mapping a >raster image to an arbitrary polygon in space? How about a pointer to a >published algorithm? Texture mapping is basically a resampling problem. First you need to generate a mapping from the image to the polygon, then you need to invert it. For every point in the target, map it back into the source, and apply a digital filter to the neighborhood of the source, so that the target image meets the Nyquist criterion (Shannon sampling theorem). A great paper, one that convinced me that the Gaussian point spread function is the best all-around PSF for image transformations and arbitrary anti-aliased graphics, is one by Feibush et al, called something like "texture mapping using digital filters", presented at the Seattle SIGGRAPH (1980?). For computational efficiency, you should look at the separable algorithm presented by Alvy Ray Smith and Ed Catmull at the same SIGGRAPH. Also is "Pyramidal Parametrics" by Lance Williams (perhaps SIGGRAPH 1981?) and a paper presented by Frank Crow at SIGGRAPH 1984. -- Ken Turkowski @ CADLINC, Menlo Park, CA UUCP: {amd,decwrl,hplabs,nsc,seismo,spar}!turtlevax!ken ARPA: turtlevax!ken@DECWRL.ARPA