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Last Post 08 Sep 2017 09:54 AM by  Jürgen Koglin
2-dimentional fit to gridded data
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Jürgen Koglin



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04 Sep 2017 10:59 AM
    I am looking for an IDL function which enables a 2-dimensional fit to gridded data, i.e. similar to the GAUSS2DFIT or the SFIT function.

    In the particular case the data is a grid array, let's say a=dblarr(x,y), where x, y and z=a(x,y) are the coordinates in the 3d space.
    The function I want to fit to my grid array could be a hemisphere, cone, or even any other mathematical area function, which can be described as z=f(x,y).

    CURVEFIT is something which is very to close to that what I need, but CURVEFIT is limited to vectors f(x), and cannot fit arrays f(x,y).

    How can I solve the problem?

    David Starbuck



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    Posts:143
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    05 Sep 2017 12:01 PM
    Would the KRIG2D routine meet your needs?
    https://www.harrisgeospatial.com/docs/KRIG2D.html

    David
    Harris GS

    Jürgen Koglin



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    08 Sep 2017 09:54 AM
    My array is already a regular gridded x,y array, which contains the e.g. the height data z(x,y). So krigging is not that what I need.

    I want to fit a well known algebraic function to the 2-dimensional z(x,y) grid data. For example: In case of a spherical function f(x,y) = sqrt ( R² - (x-x0)² - (y-y0)² ) + z0, the fit result should be at least the fit parameters R (radius) and (x0,y0,z0) apex position and apex height.

    So the IDL routine I am looking for more like the CURVEFIT routine, but with arrays and not only vectors.

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