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  • ISO C/C++ bivariate surface fit code

    From Muhammad Ali@21:1/5 to bob_wil...@my-deja.com on Tue Oct 27 01:13:19 2020
    On Friday, March 3, 2000 at 4:00:00 PM UTC+8, bob_wil...@my-deja.com wrote:
    In article <38BDFCEF...@bayarea.net>,
    ras...@bayarea.net wrote:
    Hi,
    I'm looking for C/C++ bivariate surface fit code. I've posted a
    similar

    request previously but the lack of responses lead me to believe I had
    not well-stated my request, or perhaps it is indeed something
    difficult
    to find, so I apologize if this is redundant for some, and many thanks
    to those who are able to reply, esp. via email as my ISP removes
    messages
    every day or so.

    Puzzle:
    Given a set of data points randomly positioned over a 2D area and
    of random value (or height, as you prefer)....
    ** How do I generate a regular mesh (say, 50x50 etc) of polygons
    or triangles such that the surface is
    A) a bicubic interpolation *through* the points with the
    "tightest"
    curve, and/or "least" warped by the choice of coefficients
    * again, I'm looking for that regular 50x50 mesh... I did
    get
    a couple of emails from people prescribing tesselators,
    surface
    subdivision etc, but that isn't what I had requested or
    what I'm
    looking for since, unfortunately, it doesn't fit the
    data
    as prescribed :)
    and/or
    B) well approximated as near the points as possible with "good"
    curvature, and perhaps by selection of some limit of error,
    eg. possibly using least squares and I could only guess as
    what kind of rational spline to use, whether bicubic or
    whatever..
    Is there a reason you have to form a regular rectangular mesh?
    Forming the Delaunay triagulation and then interpolating that
    triangulated network would be less costly in both time and memory.
    I have some triangulation and linear interpolation code in C that
    you might be interested in.
    If you need to do a spline interpolation, again I would encourage
    you to check out Dave Eberly's site. Paul Bourke has some helpful
    source code too, I think:
    http://www.swin.edu.au/astronomy/pbourke/
    If you're interested in my code, please reply by email.
    Bob

    Sent via Deja.com http://www.deja.com/
    Before you buy.
    hi i am really interested in knowing more about your code as i am trying to do a local bicubic surface interpolation of (x,y,z) data set that would give me the resulting control points as well as the knot vecotors in the u and v direction. Hope you could
    help

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