I'm following these tutorials to stream images to OpenCV format from the `/ardrone/image_raw` topic.
http://wiki.ros.org/cv_bridge/Tutorials/UsingCvBridgeToConvertBetweenROSImagesAndOpenCVImages
However, even though I've been able to successfully compile the driver, when i run it, I don't see any images on screen.
My code is this -
#include "ros/ros.h"
#include
#include
#include
#include
#include
#include "ardrone_autonomy/Navdata.h"
static const std::string OPENCV_WINDOW = "Image window";
class ImageConverter
{
ros::NodeHandle nh_;
image_transport::ImageTransport it_; //ImageTransport object "it_" under the namespace 'image_transport'
image_transport::Subscriber image_sub_; //Subscriber object "image_sub_"
image_transport::Publisher image_pub_; // Publisher object "image_pub_"
public:
ImageConverter(): it_(nh_)
{
// Subscribe to input video feed and publish output video feed
image_sub_ = it_.subscribe("/ardrone/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, "see_image");
ImageConverter ic;
ros::spin();
return 0;
}
After executing this, `rosrun [package_name] [driver_node]` along with a recorded `.bag `file, it is supposed to produce image stream with a circle on it.
I can see when I run `rqt_graph` both the bag file and the driver node. However, I don't see any image. What am I missing? I've lost about a week in looking at this.
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