First Commit message

src/initial_processing.cpp

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+#include "ros/ros.h"
+#include "std_msgs/String.h"
+#include "std_msgs/Bool.h" 
+#include "std_msgs/Float32.h" 
+
+
+#include <sstream>
+#include <math.h>
+
+#include <pcl/filters/passthrough.h>
+#include <pcl/conversions.h>
+#include <pcl_conversions/pcl_conversions.h>
+#include <sensor_msgs/PointCloud2.h>
+#include <visualization_msgs/Marker.h>
+
+/* 
+TBD: get to know typedef such as stringstream
+ */
+
+// define publisher
+ros::Publisher pub;
+ros::Publisher visual;
+
+typedef pcl::PointXYZRGB PointT;
+
+void cloud_cb (const sensor_msgs::PointCloud2ConstPtr& cloud_msg){
+    
+
+    // create pointer to Point Cloud in pcl
+    pcl::PointCloud<PointT>::Ptr cloud(new pcl::PointCloud<PointT>);
+
+    // convert ROS message data to point cloud in pcl
+    pcl::fromROSMsg(*cloud_msg, *cloud);
+
+    // convert to ROS data type
+    sensor_msgs::PointCloud2 output;
+    pcl::toROSMsg(*cloud, output);
+    pub.publish(output);
+}
+
+int main(int argc, char **argv){
+    
+    // specify node name and initialize ROS
+    ros::init(argc, argv, "image_processing");
+
+    // first/last node handle does the initialization of node/cleanup of used resources by node
+    ros::NodeHandle n;
+
+    // create subscriber to receive point cloud 
+    ros::Subscriber sub = n.subscribe<sensor_msgs::PointCloud2>("/zed/zed_node/point_cloud/cloud_registered", 1, cloud_cb);
+    
+    // create publisher for output processed point cloud 
+    pub = n.advertise<sensor_msgs::PointCloud2>("processed_cloud", 1);
+
+    // create publisher for visualising marker 
+    visual = n.advertise<visualization_msgs::Marker> ("marker", 1);
+
+    ros::spin(); 
+    
+}

src/pub_and_sub.cpp

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+#include "ros/ros.h"
+#include "std_msgs/String.h"
+
+#include <sstream>
+
+/* 
+TBD: get to know typedef such as stringstream
+ */
+
+void chatterCallback(const std_msgs::String::ConstPtr& msg){
+    ROS_INFO("I heard: [%s]", msg->data.c_str());
+}
+
+int main(int argc, char **argv){
+    
+    // specify node name
+    ros::init(argc, argv, "talker");
+    ros::init(argc, argv, "listener");
+
+    // first/last node handle does the initialization of node/cleanup of used resources by node
+    ros::NodeHandle n;
+
+    // create publisher
+    // publishes message of type std_msgs/String on topic chatter with given cue size
+    // NodeHandle::advertise() returns ros::Publisher object containing publish method & unadvertise when going out of scope
+    ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000);
+    ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);
+    // ros::rate object specifies frequency to loop at
+    // keeps track of how long it has been since last Rate::sleep() call & sleeps for correct amount of time
+    ros::Rate loop_rate(10);
+
+    int count = 0;
+    while (ros::ok()){
+        std_msgs::String msg;
+
+        std::stringstream ss;
+        ss << "hello world " << count;
+        msg.data = ss.str();
+
+        ROS_INFO("%s", msg.data.c_str()); // replacement for printf/cout
+
+        chatter_pub.publish(msg);
+
+        ros::spinOnce(); // added to make sure that all callbackfunctions get called 
+
+        loop_rate.sleep(); // use ros::rate object to sleep for remaining time to hit publish rate 
+        ++count;
+    }
+    //broascasting message to anyone who is connected
+    return 0;
+    
+}