1. Velodyne

Veloview

Linux 64bit

1.2 Velodyne for ROS

ROS_velodyne

A. ROS dependencies 설치

$ sudo apt-get install ros-$ROS_DISTRO-velodyne

B. 드라이버 설치

cd ~/catkin_ws/src/ && git clone https://github.com/ros-drivers/velodyne.git
cd velodyne/
rosdep install --from-paths ./ --ignore-src --rosdistro $ROS_DISTRO -y
cd ~/catkin_ws/ && catkin_make

ref : velodyne-ROS wiki

C. 확인

Velodyne 노드 실행 & 데이터 수집 : $ roslaunch velodyne_pointcloud VLP16_points.launch

메시지 출력 : $ rostopic echo /velodyne_points --noarr

rviz이용 시각화 : $ rosrun rviz rviz -f velodyne

$ roslaunch velodyne_pointcloud VPL16_points.launch pcap:=/home/soowon/Documents/County_Fair.pcap
$ rosrun velodyne_pointcloud cloud_node _calibration:=/home/velodyne_pointcloud/params/VLP16db.yaml

1.3 Calibration in ROS

After the installation, you will need to create a calibration file for the device.

복사만 하면 됨 cp /ros/indigo/share/velodyne_pointcloud/params/VLP16db.yaml ~/

we need to calibrate generate calibration data in YAML file.

벨로다인에서 제공하는 XML포맷을 YAML포맷으로 변경 $ rosrun velodyne_pointcloud gen_calibration.py 32db.xml

• The following command will generate the calibration data in a YAML file from the standard Velodyne XML file:
• 파일 위치(??) : catkin_ws/src/velodyne/velodyne_pointcloud/params/VLP16db.yaml

my_calibration.yaml이름으로 저장 $ rosrun velodyne_pointcloud gen_calibration.py 32db.xml my_calibration.yaml

• Save generated 32E calibration data in my_calibration.yaml.

런쳐 실행시 칼리브레이션 파일 지정 $ roslaunch velodyne_pointcloud 32e_points.launch calibration:=/home/robot/32db.yaml

• We have to mention the generated calibration YAML file along with the launch file:

rviz 실행 : $ rosrun rviz rviz -f velodyne

Sample data

• HDL-32/VLP-16

  • PCAP: all received packet data.
  • CSV: one frame data that is reflection intensity and distance of 0-359.9 degree.

• Velodyne HDL-64E LiDAR, LiDAR Velodyne HDL-32e LiDAR, Velodyne VLP-16 Puck

• VLP16

• VLP16 sample pcap

VeloView 뷰어 (paraview??)

• Wiki, Homepage, Github
• .pcap files 재생
• csv/txt files로 저장 가능

Point Cloud Library with Velodyne LiDAR

• Point Cloud Library (PCL) have Grabber for input data from Velodyne LiDARs.

• .pcap파일을 사용 하기 위해서는, You need build PCL with WITH_PCAP option. (Pre-built library is disabled this option.)

  • HDLGrabber : This Grabber for HDL-64E/HDL-32E.
  • VLPGrabber : This Grabber for VLP-16.

Article

• Parse pcap from HDL-32E Sensor: python, Github

• ROS support for Velodyne 3D LIDARs

• Point cloud conversions for Velodyne 3D LIDARs.

• Velodyne Lidar Python Library: HDL 64E S2 only.

• The Velodyne High Definition LiDAR (HDL) Grabber: pcap설정, cpp

pcap파일 읽어 Play하기

• pcap_reader.py: Read a .pcap file full of UDP packets from a velodyne and play them back to

#!/usr/bin/env python

# Read a .pcap file full of UDP packets from a velodyne and play them back to
# localhost:2368, for consumption by the velodyne driver.
#
# TODO: error-checking and options (looping, etc.)

import dpkt
import sys
import socket
import time

UDP_IP = "localhost"
UDP_PORT = 2368

def parse(fname):
    lasttime = -1
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    i = 0
    with open(fname, 'rb') as f:
        pcap = dpkt.pcap.Reader(f)
        for ts, buf in pcap:
            eth = dpkt.ethernet.Ethernet(buf)
            ip = eth.data
            udp = ip.data
            velodata = udp.data
            if lasttime > 0 and (ts-lasttime) > 0:
                time.sleep(ts-lasttime)
            lasttime = ts
            print('[%d] [%s] sending %d-byte message'%(i,`ts`,len(velodata)))
            sock.sendto(velodata, (UDP_IP, UDP_PORT))
            i += 1

if __name__ == '__main__':
    if len(sys.argv) < 2:
        print('ERROR: must supply pcap filename')
        sys.exit(1)
    while True:
        parse(sys.argv[1])

To prevent exception: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xd4 in position 0: invalid continuation byte we need to use binary mode for open file: dpkt.pcap.Reader(open(filename,'rb'))

pcap to rosbag 변환

서로 다른 터미널에서 실행

roscore
rosrun velodyne_driver velodyne_node _model:=VLP16 _pcap:=/your/pcap/path/data.pcap _read_once:=true
rosrun rosbag record -O your_vlp16_070815.bag /velodyne_packets

VelodyneCapture

Capture packets as pcap