docs: def _amp2d_to_3d(self, amp, sigma_x, sigma_y):
          """
          converts 3d density into 2d density parameter
          :param amp:
          :param sigma_x:
          :param sigma_y:
          :return:
          """
          return amp / (np.sqrt(np.pi) * np.sqrt(sigma_x * sigma_y * 2))