python-3.xmatplotlibmathgeometryspherical-coordinate

How to generate points on spherical surface making equal parts?


I would like to generate a sphere containing n euqal parts. For example, I want to divide my spherical surface into 36 X 36 parts. Therefore, it should contain 1296 equal parts in total. I do not have clue how to generate points in spherical (3D) space.

I want my plot looking like this but in place of line, I want only point (where two lines intersect).

I know only formulas mentioned below,

X = R * np.sin(PHI) * np.cos(THETA)
Y = R * np.sin(PHI) * np.sin(THETA)
Z = R * np.cos(PHI)

How would I generate points make equal parts in sphere?

enter image description here


Solution

  • import numpy as np
    
    def split_sphere(R = 1, horizontal_split = 36, vertical_split = 36, method="equal_angles"):
        theta = np.linspace(0,360,horizontal_split+1)
        if method == "equal_angles":
            phi = np.linspace(0, 180, vertical_split+1)
            c = np.cos(phi)
            s = np.sin(phi)
        elif method == "equal_area":
            c = np.linspace(-1, 1, vertical_split+1)
            s = 1 - c**2
        else:
            raise(ValueError('method must be "equal_angles" or "equal_area"'))
        x = R * np.outer(s, np.cos(theta))
        y = R * np.outer(s, np.sin(theta))
        z = R * np.outer(c, np.ones(horizontal_split+1))
        return x, y, z
    
    def main():
        import matplotlib.pyplot as plt
        x,y,z = split_sphere()
        fig = plt.figure()
        ax = fig.add_subplot(projection='3d')
        ax.scatter(x,y,z)
        plt.show()
    
    if __name__=='__main__':
        main()
    

    36x36 points on sphere, split along equal angles