Cannot parse the UWB data from rosbag.

[zbabqr]

hello,
I want to parse the UWB data from the rosbag. However, when I use the topic name"/uwb_endorange_info", I get an error: (unicode error) 'utf-8' codec can't decode byte 0xa1 in position 1548: invalid start byte. Do I use the wrong topic name?

[brytsknguyen]

Hi,

Can you provide the code? Also which bag file may have issue?

Below is a short program to print out the data of messages on the the /uwb_endorange_info from the eee_01.bag

#!/usr/bin/python

import argparse
import sys
import os
import rospy
import rosbag

from uwb_driver.msg import UwbRange
from geometry_msgs.msg import TwistStamped
from geometry_msgs.msg import PoseStamped
from geometry_msgs.msg import PoseWithCovarianceStamped

# Some topics needs utf8 to decode
reload(sys)  
sys.setdefaultencoding('utf8')

if __name__ == '__main__':
   
    inbag = rosbag.Bag("/mnt/1FDD5C4564388F8F/DATASETS/NTU_VIRAL/eee_01/eee_01.bag",'r')

    for topic, msg, t in inbag.read_messages():
        if topic in ['/uwb_endorange_info']:
            print "topic:",  topic, " Stamp: ", msg.header.stamp.to_sec(), "Dis: ", msg.distance, "Panchor: ", msg.responder_location.x, msg.responder_location.y, msg.responder_location.z

You should see the print out like this

[zbabqr]

The following is my code:

import roslib
import rosbag
import rospy
import cv2
from sensor_msgs.msg import Image
from cv_bridge import CvBridge
from cv_bridge import CvBridgeError

path='./eee_01/left/image_raw/'
if name == 'main':
bridge = CvBridge()
with rosbag.Bag('./eee_01/eee_01.bag', 'r') as bag:
for topic, msg, t in bag.read_messages("/left/image_raw"):
try:
cv_image = bridge.imgmsg_to_cv2(msg,"bgr8")
except CvBridgeError as e:
print(e)
timeq = msg.header.stamp.to_sec()
timestr = "{:.6f}".format(timeq)
image_name = timestr + ".png"
#cv2.imwrite(path + image_name, cv_image)
cv2.imshow("cv_image", cv_image)
cv2.waitKey(1)
print(image_name)

    with open("./eee_01/IMUData.txt", 'w') as IMU_file:
        IMU_file.write("TimeStamps GyroscopeX GyroscopeY GyroscopeZ AccelerometerX AccelerometerY AccelerometerZ\n")
        for topic, msg, t in bag.read_messages("/imu/imu"):
            acc_x = "%.6f" % msg.linear_acceleration.x
            acc_y = "%.6f" % msg.linear_acceleration.y
            acc_z = "%.6f" % msg.linear_acceleration.z
            w_y = "%.6f" % msg.angular_velocity.y
            w_x = "%.6f" % msg.angular_velocity.x
            w_z = "%.6f" % msg.angular_velocity.z
            timeimu = "%.6f" %  msg.header.stamp.to_sec()
            imudata = timeimu + " " + w_x + " " + w_y + " " + w_z + " " + acc_x + " " + acc_y + " " + acc_z
            IMU_file.write(imudata)
            IMU_file.write('\n')
        IMU_file.close()

    for topic, msg, t in bag.read_messages("/uwb_endorange_info"):
        timeUWB = "%.6f" %  msg.header.stamp.to_sec()
        requester_id = msg.requester_id
        responder_id = msg.responder_id
        uwbData = timeUWB + " " + str(requester_id) + " " + str(responder_id)
        print(uwbData)
        #UWB_file.write(uwbData)
        #UWB_file.write('\n')

[zbabqr]

I use python 3.7

[brytsknguyen]

It looks like you're missing the import of the uwb message definition. Can you git clone the package https://github.com/ntu-aris/uwb_driver to the workspace, catkin make / build the workspace, add from uwb_driver.msg import UwbRange to the beginning of python script, and try again?

Below is a short modification of your code to make it work. I am using python 3.6

import roslib
import rosbag
import rospy
import rosbag

from uwb_driver.msg import UwbRange # Install from https://github.com/ntu-aris/uwb_driver

bag = rosbag.Bag("/mnt/1FDD5C4564388F8F/DATASETS/NTU_VIRAL/eee_01/eee_01.bag",'r')
    
for topic, msg, t in bag.read_messages("/uwb_endorange_info"):
    timeUWB = "%.6f" %  msg.header.stamp.to_sec()
    requester_id = msg.requester_id
    responder_id = msg.responder_id
    uwbData = timeUWB + " " + str(requester_id) + " " + str(responder_id)
    print(uwbData)