generate_gaussian_kernel.ipynb

import numpy as np
from mpl_toolkits.mplot3d import axes3d
import matplotlib.pyplot as plt
from matplotlib import cm
import re

# Set the radius to generate a C++-source-ready gaussian kernel in a multidimensional array
RADIUS = 6


def generate_gaussian_kernel(radius, sigma = 3, central_value = 3.5):
    # Generate a size x size grid
    a = np.linspace(-radius, radius, 2 * radius + 1)
    b = a
    x, y = np.meshgrid(a, b)

    return x, y, np.exp(-(x / sigma)**2 - (y / sigma)**2) * central_value


xgrid, ygrid, mat = generate_gaussian_kernel(RADIUS)

fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.plot_surface(xgrid, ygrid, mat, rstride=1, cstride=1, cmap='CMRmap')
plt.show()

# Pretty print for C++ inclusion

mat_str = '{\n'
for j in range(0, len(mat)):
    row = mat[j]
    mat_str += '{'
    for i in range(0, len(row)):
        value = row[i]
        value_str = '{0:.16f}f'.format(value)
        mat_str += value_str
        if i != len(row) - 1:
            mat_str += ', '
    if j != len(mat) - 1:
        mat_str += '},\n'
    else:
        mat_str += '}\n'
mat_str += '}'

str = '''#define KERNEL_RADIUS %d\n#define KERNEL_WIDTH %d\n#define KERNEL_HEIGHT %d\n
const float gaussian_kernel[KERNEL_HEIGHT][KERNEL_WIDTH] = \n%s;''' % (RADIUS, 2 * RADIUS + 1, 2 * RADIUS + 1, mat_str)
print str