how to publish sensor_msgs::CameraInfo messages?

Question

I am unable to publish the CameraInfo messages. I have the image data published from the camera using the image_transport::Publisher but the same is not publishing the camera info messages.

I am writing a driver for the ueye camera. I need the camera info message for calibration of the camera. I am able to detect the corners in the chessboard but then the program hangs after completion may be because it could not find the camera info messages containing the camera model.

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Originally posted by abhinav on ROS Answers with karma: 141 on 2011-09-29

Post score: 2

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Original comments

Comment by Farid on 2018-11-02:
I think this link might answer your question.

Answer 1

The recommended method is to use image_transport and camera_info_manager.

Here's how camera1394 does it:

  /** Publish camera stream topics
   *
   *  @param image points to latest camera frame
   */
  void Camera1394Driver::publish(const sensor_msgs::ImagePtr &image)
  {
    image->header.frame_id = config_.frame_id;
  
    // get current CameraInfo data
    sensor_msgs::CameraInfoPtr
      ci(new sensor_msgs::CameraInfo(cinfo_->getCameraInfo()));

    // check whether CameraInfo matches current video mode
    if (!dev_->checkCameraInfo(*image, *ci))
      {
        // image size does not match: publish a matching uncalibrated
        // CameraInfo instead
        if (calibration_matches_)
          {
            // warn user once
            calibration_matches_ = false;
            ROS_WARN_STREAM("[" << camera_name_
                            << "] calibration does not match video mode "
                            << "(publishing uncalibrated data)");
          }
        ci.reset(new sensor_msgs::CameraInfo());
        ci->height = image->height;
        ci->width = image->width;
      }
    else if (!calibration_matches_)
      {
        // calibration OK now
        calibration_matches_ = true;
        ROS_WARN_STREAM("[" << camera_name_
                        << "] calibration matches video mode now");
      }

    // fill in operational parameters
    dev_->setOperationalParameters(*ci);

    ci->header.frame_id = config_.frame_id;
    ci->header.stamp = image->header.stamp;

    // @todo log a warning if (filtered) time since last published
    // image is not reasonably close to configured frame_rate
  
    // Publish via image_transport
    image_pub_.publish(image, ci);
  }

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Originally posted by joq with karma: 25443 on 2011-09-29

This answer was ACCEPTED on the original site

Post score: 3

Answer 2

Declare your publisher, I do this in main:

ros::Publisher pub_info_left = nh.advertise<sensor_msgs::CameraInfo>("left/camera_info", 1);
sensor_msgs::CameraInfo info_left;

Then, in a callback function or in a while() loop in main do this:

info_left.header.stamp = ros::Time::now();
pub_info_left.publish(info_left);

I have implemented this in an approximate time synchronization node where I subscribe to the image and info topics from two different cameras, set all of their timestamps equal to each other then republish on those four topics here. That would be a more complete code example if the one above is not clear enough.

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Originally posted by Thomas D with karma: 4347 on 2011-09-29

This answer was NOT ACCEPTED on the original site

Post score: 1

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Original comments

Comment by Thomas D on 2011-09-29:
@joq's answer is better than this one, not least because it is the recommended method and we should be trying to do things in a standard way.

Comment by TimboInSpace on 2014-12-15:
To add to Thomas D's comment, another way to do this would be using message_filters::TimeSynchronizer, set up to subscribe to each camera