velodyne_pointcloud_to_depthimage

Generate depth images from velodyne point cloud.

DEMO

Features

• Subscribe:
  • "/velodyne_points" (sensor_msgs::PointCloud2)
• Publish:
  • "/depth_image/64fc1" (sensor_msgs::Image) (64FC1)
  • "/depth_image/16uc1" (sensor_msgs::Image) (mono16)
  • "/depth_image/8uc1" (sensor_msgs::Image) (mono8)
• Save (optional):
  • "***.xml" (CV_64FC1<double>)
  • "***.jpg" (CV_16UC1<unsigned short>)
  • "***.jpg" (CV_8UC1<unsigned char>)

Requirement

• ROS
• PCL
• OpenCV

Installation

$ cd ~/catkin_ws/src
$ git clone https://github.com/ozakiryota/velodyne_pointcloud_to_depthimage
$ cd ~/catkin_ws
$ catkin_make

Usage

Edit the launch file

• Set your bag file path.
• Set parameters
  • {num_ring}
    number of velodyne sensor's layers
  • {points_per_ring}
    number of points per ring
  • {depth_resolution}
    resolution of depth (for "mono16")
    (ex. when depth_resolution is 0.1, 1.234 m is registered as 12 in grayscale)
  • {max_range}
    max range of laser (for "mono8")
  • {save_limit}
    maximum number for saving jpg images
    (if you don't want to save any images, set as save_limit=-1)
  • {save_root_path}
    path to directory for saving whole datas
  • {save_img_name}
    name of saved image file
    (images are saved as "{save_root_path}/{save_img_name}0_8u.jpg", "{save_root_path}/{save_img_name}1_8u.jpg",,,)

Launch

$ roslaunch velodyne_pointcloud_to_depthimage velodyne_pointcloud_to_depthimage.launch

Note

Data type

• 64FC1<double>: 2.2250738585072014e-308 ~ 1.7976931348623158e+308
• mono16<unsigned short>: 0 ~ 65535
• mono8<unsigned char>: 0 ~ 255

ROS -> CV

C++

#include <sensor_msgs/Image.h>
#include <opencv2/opencv.hpp>
#include <cv_bridge/cv_bridge.h>
sensor_msgs::ImagePtr ros_msg;
cv_bridge::CvImagePtr cv_ptr = cv_bridge::toCvCopy(ros_msg, ros_msg->encoding);
cv::Mat cv_mat = cv_ptr->image

Python

from sensor_msgs.msg import Image
from cv_bridge import CvBridge
ros_img = Image()
bridge = CvBridge()
cv_img = bridge.imgmsg_to_cv2(ros_img, ros_img.encoding)

Load .xml

cv::FileStorage fs("example/depth_0_64f.xml", cv::FileStorage::READ);
if (!fs.isOpened()){
    std::cout << "File can not be opened." << std::endl;
    exit(1);
}
cv::Mat mat;
fs["mat"] >> mat;