Following the beginner cv_bridge tutorials, doesn't work - c++

Question

I am trying to bridge Ros images to OpenCV so i started using cv_bridge and followed this tutorial. http://wiki.ros.org/cv_bridge/Tutorials/UsingCvBridgeToConvertBetweenROSImagesAndOpenCVImages
I think I was able to make the CMakeLists.txt file correct and using catkin_make does build the executable and the code runs, however nothing really happens besides the node showing up as a leaf topic when using rqt_graph.
However, i ran into some issues with the line of the tutorial where it says: Run a camera or play a bag file to generate the image stream. Now you can run this node, remapping "in" to the actual image stream topic.
I am using a Kinect for the image source and have installed the openni drivers and can confirm that it is working correctly, as when i run rviz or rtabmap point cloud images is being shown.
I'm guessing the issue is that i am not mapping the publishers and subscribers correctly, as when i am trying to use image_view to see if the camera data is working it returns blank. In the command line, i am typing in: rosrun image_view image_view image:=/camera/rgb/image_color However, I am receiving this error: GLib-GObject-CRITICAL **: 15:13:13.357: g_object_unref: assertion 'G_IS_OBJECT (object)' failed, which i'm assuming is an error with me renaming the topics.
When running rqt_graph with both the openni node and the tutorial file it looks like the this.
https://imgur.com/fLd69WG
#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
static const std::string OPENCV_WINDOW = "Image window";
class ImageConverter
{
ros::NodeHandle nh_;
image_transport::ImageTransport it_;
image_transport::Subscriber image_sub_;
image_transport::Publisher image_pub_;
public:
ImageConverter()
: it_(nh_)
{
// Subscrive to input video feed and publish output video feed
//I'm guessing this is where my errors are
image_sub_ = it_.subscribe("/camera/image_raw", 1,
&ImageConverter::imageCb, this);
image_pub_ = it_.advertise("/image_converter/output_video", 1);
cv::namedWindow(OPENCV_WINDOW);
}
~ImageConverter()
{
cv::destroyWindow(OPENCV_WINDOW);
}
void imageCb(const sensor_msgs::ImageConstPtr& msg)
{
cv_bridge::CvImagePtr cv_ptr;
try
{
cv_ptr = cv_bridge::toCvCopy(msg, sensor_msgs::image_encodings::BGR8);
}
catch (cv_bridge::Exception& e)
{
ROS_ERROR("cv_bridge exception: %s", e.what());
return;
}
// Draw an example circle on the video stream
if (cv_ptr->image.rows > 60 && cv_ptr->image.cols > 60)
cv::circle(cv_ptr->image, cv::Point(50, 50), 10, CV_RGB(255,0,0));
// Update GUI Window
cv::imshow(OPENCV_WINDOW, cv_ptr->image);
cv::waitKey(3);
// Output modified video stream
image_pub_.publish(cv_ptr->toImageMsg());
}
};
int main(int argc, char** argv)
{
ros::init(argc, argv, "image_converter");
ROS_INFO_STREAM("test to see if node is running");
ImageConverter ic;
ros::spin();
return 0;
}

Answer 1

I have fixed the issue by using rostpic hz [topic] and checking which ones are receiving camera data. From there, I changed the subscriber to image_sub_ = it_.subscribe("camera/rgb/image_color", 1, &ImageConverter::imageCb, this); and it worked