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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
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