Algorithm 1 Algorithm of initial position determination

for k in [1, fov*Nz]   z_max = −∞   for j in [1, fov*Ny]     y_max = −∞     prev_x_max = −∞     for i in [1, fov*Nx]       generate particle with random size r       if i = 1 then         x_min = r       else         x_min = prev_x_max + r       if j = 1 then         y_min = r       else         y_min = prev_y_max + r       if k = 1 then         z_min = r       else         z_min = prev_z_max + r       x_new = u(x_min, x_min+init_noise)       y_new = u(y_min, y_min+init_noise)       y_new = u(z_min, z_min+init_noise)       place the newly generated particle at (x_new, y_new, z_new)       prev_x_max = max(prev_x_max, x_new+r)       y_max = max(y_max, y_new+r)       z_max = max(z_max, z_new+r)     prev_y_max = y_max   prev_z_max = z_max