surface-fitter 0.16

Least-square fitting of 3D surface to data points in text file

surface_fitter

Developed by Marcin Sokolowski ([e-mail]) , version 0.1x, 2025-07 Fits a surface represented by a polynomial of an arbitrary order by calculating derivative over each coefficient, equalling them to zero and forming as many equations as many parameters

Requirements : matplotlib scipy numpy

Installation and test:

 # pip install -i https://test.pypi.org/simple/ surface-fitter
 # pip install numpy scipy matplotlib
 
 # test:
 python
 import surface_fitter
 surface_fitter.generate_data("test.txt")
 surface_fitter.fit_poly("test.txt",polynomial_order=3)
 surface_fitter.plot_scatter("fitted_order03.txt",verbose=1)   

Example usage and test when source code is used (not pip) :

 # generates points from surface : val = 2.0*xp**3 + 1.0*(xp**2)*(yp) + 3.0*(xp)*(yp**2) + 4*xp*yp + 3*xp + yp + 10 
 python ./surface_generator.py > test.txt

 # fit 3 order polynomial:
 python ./fit_poly_3d.py test.txt --order=3 

 # check if fitted polynomial is the same as generated :
 Fitted polynomial p_n(x,y) =  10.00000000*(x**0)*(y**0) +  1.00000000*(x**0)*(y**1) +  0.00000000*(x**0)*(y**2) +  0.00000000*(x**0)*(y**3) +  3.00000000*(x**1)*(y**0) +  4.00000000*(x**1)*(y**1) +  
                               3.00000000*(x**1)*(y**2) +  0.00000000*(x**2)*(y**0) +  1.00000000*(x**2)*(y**1) +  2.00000000*(x**3)*(y**0)

 # plot fitted surface :
 python ./plot_scatter_3d.py fitted_vs_data_order03.txt --vmin=0 --vmax=20

 # plot data :
 python ./plot_scatter_3d.py fitted_vs_data_order03.txt --vmin=0 --vmax=20

 # plot residuals :
python ./plot_scatter_3d.py fitted_vs_data_order03.txt --vmin=-4 --vmax=+4

USAGE : python ./fit_poly_3d.py 3_COLUMN_TEXT_FILE_X_Y_Z.txt --order=3

 Options : 
    --order=3 : fits 3rd order polynomial, i.e. p(x,y) = a30 x^3 + a31 x^2 y^1 + a32 x^1 y^2 + a33 x^0 y^3 + a20 x^2 + a21 x^1 y^1 + a22 x^0 y^2 + a10 X^1 + a11 y^1 + a00
    --vmin    : minimum value on Z axis
    --vmax    : maximum value on Z axis
    --image_size : image size, default 8192, when set to 0 (--image_size=0) it will be automatically calculated as max(x)
    --verb    : verbosity level [default 0]

OUTPUT FILES : For example for a 3rd order polynomial fit as in the example above :

   fitted_order03.txt         - ext file with fitted values, with higher resolution in X and Y (default step = 10 pixels), 3 columns : X Y FITTED_VALUE
   fitted_vs_data_order03.txt - text file with data and fitted surface 5 columns : X Y FITTED_VALUE DATA_VALUE RESIDUAL(=DATA-FIT)