Initial estimation of sigma2 fails for FilterReg about probreg HOT 3 CLOSED

import numpy as np
import transformations as trans
from probreg import filterreg
from probreg import callbacks
from probreg import math_utils as mu
import open3d as o3

sdata = np.loadtxt("frames/frame00000.txt")
tdata = np.loadtxt("frames/frame00001.txt")

def estimate_normals(pcd, params):
    pcd.estimate_normals(search_param=params)
    pcd.orient_normals_to_align_with_direction()

source = o3.geometry.PointCloud()
source.points = o3.utility.Vector3dVector(sdata)
target = o3.geometry.PointCloud()
target.points = o3.utility.Vector3dVector(tdata)
estimate_normals(target, o3.geometry.KDTreeSearchParamHybrid(radius=0.5, max_nn=50))

cbs = [callbacks.Open3dVisualizerCallback(source, target)]
objective_type = 'pt2pt'
tf_param, _, _ = filterreg.registration_filterreg(source, target,
                                                  #target_normals=np.asarray(target.normals),
                                                  objective_type=objective_type,
                                                  sigma2=1.0,
                                                  callbacks=cbs)
rot = trans.identity_matrix()
rot[:3, :3] = tf_param.rot
print("result: ", np.rad2deg(trans.euler_from_matrix(rot)),
      tf_param.scale, tf_param.t)