This article is a supplement to the CSDN blog that uses the subscription function of ROS topics to extract information from bag files_rosbag extracts multiple topic information.
ROS creates workspace code with one click
conda deactivate # if necessary # Check path echo "the current space is " pwd #Initialize workspace mkdir -p ./rosbag-ext/src cd ./rosbag-ext/src catkin_init_workspace cd.. catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3 # Set environment variables source ./devel/setup.bash echo "the ros path is" # Check environment variables echo $ROS_PACKAGE_PATH # catkin_create_pkg <package_name> [depend_1] [depend_2] [depend_n] # Function package # Where extract is the function package name, followed by dependencies catkin_create_pkg extract cv_bridge roscpp std_msgs sensor_msgs # Compile function package catkin_make source ./devel/setup.bash
Code for subscribing to topics
//This code is used to get the topic in rosbag #include <ros/ros.h> #include<sensor_msgs/Image.h> #include <opencv2/opencv.hpp> #include<cv_bridge/cv_bridge.h> #include<iostream> #include<string> #include<vector> using namespace std; vector<double> image_times; vector<cv::Mat> images; string yaml = "/home/nm/ros-learn/rosbag-ext/src/extract/src/topicpath.yaml"; string ImageTopic; string ImagePath; string TimePath; int i = 0; void readParameters(ros::NodeHandle &n) { std:string config_file; config_file = yaml; cv::FileStorage fsSettings(config_file, cv::FileStorage::READ); if(! fsSettings.isOpened()) { std::cerr << "ERROR: wrong path to settings" << std::endl; } fsSettings["image_topic"] >> ImageTopic; fsSettings["image_path"] >> ImagePath; fsSettings["time_path"] >> TimePath; fsSettings.release(); } void imageCallback(const sensor_msgs::ImageConstPtr & amp;img_msg) { cv_bridge::CvImageConstPtr ptr; ptr = cv_bridge::toCvCopy(img_msg, img_msg->encoding); cv::Mat show_img = ptr -> image; string str1, image_path; stringstream ss1; cout << "sub No." << i << " image from topic" << endl; ss1 << i; ss1 >> str1; + + i; image_path = ImagePath + str1 + ".png"; cv::imwrite(image_path, show_img); } // rosrun extract nm_subscriber int main(int argc, char** argv) { // yaml = argv[1]; // yaml = "/home/nm/ros-learn/rosbag-ext/src/extract/src/topicpath.yaml"; //Initialize ROS node ros::init(argc, argv, "nm_image_sub"); //Create node handle ros::NodeHandle node; readParameters(node); cout << "Image Path == " << yaml << endl; // ros::Subscriber image_sub = node.subscribe(IMAGE_TOPIC, 1000, imageCallback); // Subscribe to image information // ros::Subscriber sub_imu = node.subscribe(IMU_TOPIC, 2000, imu_callback); // Subscribe to imu information ros::Subscriber img_sub = node.subscribe(ImageTopic,5000,imageCallback); ros::spin(); return 0; } /* packet rosbag info path: ./Datasets/MH_01_easy.bag version: 2.0 duration: 3:06s (186s) start: Jun 25 2014 03:02:59.81 (1403636579.81) end: Jun 25 2014 03:06:06.70 (1403636766.70) size: 2.5 GB messages: 47283 compression: none [2456/2456 chunks] types: geometry_msgs/PointStamped [c63aecb41bfdfd6b7e1fac37c7cbe7bf] sensor_msgs/Image [060021388200f6f0f447d0fcd9c64743] sensor_msgs/Imu [6a62c6daae103f4ff57a132d6f95cec2] topics: /cam0/image_raw 3682 msgs : sensor_msgs/Image /cam1/image_raw 3682 msgs : sensor_msgs/Image /imu0 36820 msgs : sensor_msgs/Imu /leica/position 3099 msgs : geometry_msgs/PointStamped */
YAML stores various addresses
%YAML:1.0 # the save path of image image_path: "/home/nm/ros-learn/Datasets/temp/image/" # the name of image topic image_topic: /cam0/image_raw # the name of imu topic imu_topic: /imu0
CMakeLists
cmake_minimum_required(VERSION 3.0.2) project(extract) ## Compile as C++11, supported in ROS Kinetic and newer # add_compile_options(-std=c++11) ## Find catkin macros and libraries ## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz) ## is used, also find other catkin packages find_package(catkin REQUIRED COMPONENTS cv_bridge roscpp sensor_msgs std_msgs ) ## System dependencies are found with CMake's conventions # find_package(Boost REQUIRED COMPONENTS system) ## Uncomment this if the package has a setup.py. This macro ensures ## modules and global scripts declared therein get installed ## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html #catkin_python_setup() ############################################### ## Declare ROS messages, services and actions ## ############################################### ## To declare and build messages, services or actions from within this ## package, follow these steps: ## * Let MSG_DEP_SET be the set of packages whose message types you use in ## your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...). ## * In the file package.xml: ## * add a build_depend tag for "message_generation" ## * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET ## * If MSG_DEP_SET isn't empty the following dependency has been pulled in ## but can be declared for certainty nevertheless: ## * add a exec_depend tag for "message_runtime" ## * In this file (CMakeLists.txt): ## * add "message_generation" and every package in MSG_DEP_SET to ## find_package(catkin REQUIRED COMPONENTS ...) ## * add "message_runtime" and every package in MSG_DEP_SET to ## catkin_package(CATKIN_DEPENDS ...) ## * uncomment the add_*_files sections below as needed ## and list every .msg/.srv/.action file to be processed ## * uncomment the generate_messages entry below ## * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...) ## Generate messages in the 'msg' folder # add_message_files( #FILES #Message1.msg #Message2.msg # ) ## Generate services in the 'srv' folder # add_service_files( #FILES # Service1.srv # Service2.srv # ) ## Generate actions in the 'action' folder # add_action_files( #FILES # Action1.action # Action2.action # ) ## Generate added messages and services with any dependencies listed here # generate_messages( #DEPENDENCIES # sensor_msgs# std_msgs # ) ############################################### ## Declare ROS dynamic reconfigure parameters ## ############################################### ## To declare and build dynamic reconfigure parameters within this ## package, follow these steps: ## * In the file package.xml: ## * add a build_depend and a exec_depend tag for "dynamic_reconfigure" ## * In this file (CMakeLists.txt): ## * add "dynamic_reconfigure" to ## find_package(catkin REQUIRED COMPONENTS ...) ## * uncomment the "generate_dynamic_reconfigure_options" section below ## and list every .cfg file to be processed ## Generate dynamic reconfigure parameters in the 'cfg' folder # generate_dynamic_reconfigure_options( #cfg/DynReconf1.cfg #cfg/DynReconf2.cfg # ) ################################### ## catkin specific configuration ## ################################### ## The catkin_package macro generates cmake config files for your package ## Declare things to be passed to dependent projects ## INCLUDE_DIRS: uncomment this if your package contains header files ## LIBRARIES: libraries you create in this project that dependent projects also need ## CATKIN_DEPENDS: catkin_packages dependent projects also need ## DEPENDS: system dependencies of this project that dependent projects also need catkin_package( # INCLUDE_DIRS include # LIBRARIES extract CATKIN_DEPENDS cv_bridge roscpp sensor_msgs std_msgs # DEPENDS system_lib ) ########### ## Build ## ########### ## Specify additional locations of header files ## Your package locations should be listed before other locations include_directories( #include ${catkin_INCLUDE_DIRS} ) ## Declare a C++ library # add_library(${PROJECT_NAME} # src/${PROJECT_NAME}/extract.cpp # ) ## Add cmake target dependencies of the library ## as an example, code may need to be generated before libraries ## either from message generation or dynamic reconfigure # add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS}) ## Declare a C++ executable ## With catkin_make all packages are built within a single CMake context ## The recommended prefix ensures that target names across packages don't collide # add_executable(${PROJECT_NAME}_node src/extract_node.cpp) ## Rename C++ executable without prefix ## The above recommended prefix causes long target names, the following renames the ## target back to the shorter version for ease of user use ## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node" # set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "") ## Add cmake target dependencies of the executable ## same as for the library above # add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS}) ## Specify libraries to link a library or executable target against # target_link_libraries(${PROJECT_NAME}_node # ${catkin_LIBRARIES} # ) add_executable(nm_subscriber /home/nm/ros-learn/rosbag-ext/src/extract/src/sub.cpp) target_link_libraries(nm_subscriber ${catkin_LIBRARIES}) ############# ## Install ## ############# # all install targets should use catkin DESTINATION variables # See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html ## Mark executable scripts (Python etc.) for installation ## in contrast to setup.py, you can choose the destination # catkin_install_python(PROGRAMS # scripts/my_python_script # DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION} # ) ## Mark executables for installation ## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html # install(TARGETS ${PROJECT_NAME}_node # RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION} # ) ## Mark libraries for installation ## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html # install(TARGETS ${PROJECT_NAME} # ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION} # LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION} # RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION} # ) ## Mark cpp header files for installation # install(DIRECTORY include/${PROJECT_NAME}/ # DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION} # FILES_MATCHING PATTERN "*.h" # PATTERN ".svn" EXCLUDE # ) ## Mark other files for installation (e.g. launch and bag files, etc.) # install(FILES # # myfile1 # # myfile2 # DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION} # ) ############# ## Testing ## ############# ## Add gtest based cpp test target and link libraries # catkin_add_gtest(${PROJECT_NAME}-test test/test_extract.cpp) # if(TARGET ${PROJECT_NAME}-test) # target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME}) #endif() ## Add folders to be run by python nosetests #catkin_add_nosetests(test)