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How to extract XYZ data from .pcap file

asked 2016-02-22 23:43:16 -0500

Soowon gravatar image

updated 2016-02-24 10:06:04 -0500

joq gravatar image

Hello, I am a complete freshman on Linux, ROS so, don't be mad :). I have a Velodyne VLP16 and the list that I want to with this laser is:

  1. Acquire raw data (.pcap)
  2. Visualize it using 3D viewer
  3. Extract XYZ and Intensity data from acquired raw data

What I accomplished so far is only No.2 using commands below (I downloaded .pcap file from velodyne website):

$ roslaunch velodyne_pointcloud VPL16_points.launch pcap:=/home/soowon/Documents/County_Fair.pcap

$ rosrun velodyne_pointcloud cloud_node _calibration:=/home/soowon/catkin_ws/src/velodyne-master/velodyne_pointcloud/params/VLP16db.yaml

$ rosrun rviz rviz -f velodyne

$ Add -> By topic -> /velodyne_points -> PointCloud2

By commands above, I was able to see pointcloud using RViz. Now here's my questions:

  1. I followed tutorial ( http://wiki.ros.org/velodyne/Tutorial... ) to establish connection using command below,

    $ sudo ifconfig eth0 192.168.3.100

    $ sudo route add 192.168.XX.YY eth0

however, according to wireshark, connection wasn't established at all.

  1. Now I can see (gladly) the pointcloud, I really want to extract X,Y, and Z coordinates with intensity from .pcap file. I found some great sources to start ( https://github.com/PointCloudLibrary/pcl ), but I am not sure whether I can pull this off by myself :(

Any advice would be superb!! Thank you :)

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The VPL16_points.launch script will run the cloud nodelet for you, so the rosrun velodyne_pointcloud cloud_node is unnecessary.

joq gravatar image joq  ( 2016-02-24 16:35:22 -0500 )edit
1

Since you seem to be able to view the point cloud, I am uncertain what your exact question is. Are you asking about how to do the connection? Or, are you wondering how to write a ROS node that processes the data?

joq gravatar image joq  ( 2016-02-24 16:37:52 -0500 )edit

I would be really interested in the second question you mention.. how to write a ROS node that processes the data?

siaca gravatar image siaca  ( 2016-10-12 07:27:11 -0500 )edit

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answered 2016-10-13 10:17:48 -0500

joq gravatar image

Here is a fairly simple package that processes Velodyne data into a height map.

The source code is here: https://github.com/jack-oquin/velodyn...

Despite its simplicity, it's fairly robust at detecting obstacles, although it is sometimes subject to false positives due to things like overhanging tree branches.

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This package is only for Indigo! :(

Farid gravatar image Farid  ( 2018-09-24 03:45:37 -0500 )edit
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answered 2018-11-15 06:17:12 -0500

Kranti gravatar image

Hi,

I am also looking for similar solution. Any success here?

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Asked: 2016-02-22 23:43:16 -0500

Seen: 3,314 times

Last updated: Nov 15 '18