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From: sg04@harvey.gte.com (Steven Gutfreund)
Newsgroups: comp.graphics,bit.listserv.gis-l
Subject: surface fit
Message-ID: <9949@bunny.GTE.COM>
Date: 1 Nov 90 15:29:53 GMT
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I am looking for advice from someone with some
practical experience in surface fitting. (i.e.
I know how to read Foley & Van Dam, but I need help
in narrowing the range of my study).

I want to fit a surface to a set of 3D points. I
have a GIS data set of data on the x-y plane.
The points are scattered in the x-y plane in the
range (0,0)..(64000,64000). The Z plane is fairly
smooth (30-40) but perhaps some anomolies.

There are three data sets sizes (2000, 7000, 100000).

From the surface fit I want to obtain a regular grid
of x,y data points whose z values are smoothly sampled
from the surrounding actual values. The x,y grid will
be about 200x200.

1) I want a fairly fast (for a sparcstation) algorithm
   that is easy for a novice to implement, and will give
   fairly smooth results. Should I look at the spline,
   cubic-spline, nurb, fit routines or something else?
   I have Foley&VanDam (editions 1 & 2). And also a book
   called Curve and Surface fitting an introduction by
   Peter Lancaster. Basically, I need a cookbook approach.

2) How do I rapidly find the neighboring points to my
   grid points. I will need these points for control points
   for my surface fit algorithm.

3) About how many control points do I need to do a fairly
   smooth (locally) fit?

Thanx.

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Yechezkal Shimon Gutfreund		 		  sgutfreund@gte.com
GTE Laboratories, Waltham MA			    harvard!bunny!sgutfreund
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Yechezkal Shimon Gutfreund		 		  sgutfreund@gte.com
GTE Laboratories, Waltham MA			    harvard!bunny!sgutfreund
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